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.\" Automatically generated by Pod::Man 2.25 (Pod::Simple 3.20) .\" .\" Standard preamble: .\" ======================================================================== .de Sp \" Vertical space (when we can't use .PP) .if t .sp .5v .if n .sp .. .de Vb \" Begin verbatim text .ft CW .nf .ne \\$1 .. .de Ve \" End verbatim text .ft R .fi .. .\" Set up some character translations and predefined strings. \*(-- will .\" give an unbreakable dash, \*(PI will give pi, \*(L" will give a left .\" double quote, and \*(R" will give a right double quote. \*(C+ will .\" give a nicer C++. Capital omega is used to do unbreakable dashes and .\" therefore won't be available. \*(C` and \*(C' expand to `' in nroff, .\" nothing in troff, for use with C<>. .tr \(*W- .ds C+ C\v'-.1v'\h'-1p'\s-2+\h'-1p'+\s0\v'.1v'\h'-1p' .ie n \{\ . ds -- \(*W- . ds PI pi . if (\n(.H=4u)&(1m=24u) .ds -- \(*W\h'-12u'\(*W\h'-12u'-\" diablo 10 pitch . if (\n(.H=4u)&(1m=20u) .ds -- \(*W\h'-12u'\(*W\h'-8u'-\" diablo 12 pitch . ds L" "" . ds R" "" . ds C` "" . ds C' "" 'br\} .el\{\ . ds -- \|\(em\| . ds PI \(*p . ds L" `` . ds R" '' 'br\} .\" .\" Escape single quotes in literal strings from groff's Unicode transform. .ie \n(.g .ds Aq \(aq .el .ds Aq ' .\" .\" If the F register is turned on, we'll generate index entries on stderr for .\" titles (.TH), headers (.SH), subsections (.SS), items (.Ip), and index .\" entries marked with X<> in POD. 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Always turn off hyphenation; it makes .\" way too many mistakes in technical documents. .if n .ad l .nh .SH "NAME" perl561delta \- what's new for perl v5.6.1 .SH "DESCRIPTION" .IX Header "DESCRIPTION" This document describes differences between the 5.005 release and the 5.6.1 release. .SH "Summary of changes between 5.6.0 and 5.6.1" .IX Header "Summary of changes between 5.6.0 and 5.6.1" This section contains a summary of the changes between the 5.6.0 release and the 5.6.1 release. More details about the changes mentioned here may be found in the \fIChanges\fR files that accompany the Perl source distribution. See perlhack for pointers to online resources where you can inspect the individual patches described by these changes. .SS "Security Issues" .IX Subsection "Security Issues" suidperl will not run /bin/mail anymore, because some platforms have a /bin/mail that is vulnerable to buffer overflow attacks. .PP Note that suidperl is neither built nor installed by default in any recent version of perl. Use of suidperl is highly discouraged. If you think you need it, try alternatives such as sudo first. See http://www.courtesan.com/sudo/ . .SS "Core bug fixes" .IX Subsection "Core bug fixes" This is not an exhaustive list. It is intended to cover only the significant user-visible changes. .ie n .IP """UNIVERSAL::isa()""" 4 .el .IP "\f(CWUNIVERSAL::isa()\fR" 4 .IX Item "UNIVERSAL::isa()" A bug in the caching mechanism used by \f(CW\*(C`UNIVERSAL::isa()\*(C'\fR that affected base.pm has been fixed. The bug has existed since the 5.005 releases, but wasn't tickled by base.pm in those releases. .IP "Memory leaks" 4 .IX Item "Memory leaks" Various cases of memory leaks and attempts to access uninitialized memory have been cured. See \*(L"Known Problems\*(R" below for further issues. .IP "Numeric conversions" 4 .IX Item "Numeric conversions" Numeric conversions did not recognize changes in the string value properly in certain circumstances. .Sp In other situations, large unsigned numbers (those above 2**31) could sometimes lose their unsignedness, causing bogus results in arithmetic operations. .Sp Integer modulus on large unsigned integers sometimes returned incorrect values. .Sp Perl 5.6.0 generated \*(L"not a number\*(R" warnings on certain conversions where previous versions didn't. .Sp These problems have all been rectified. .Sp Infinity is now recognized as a number. .IP "qw(a\e\eb)" 4 .IX Item "qw(ab)" In Perl 5.6.0, qw(a\e\eb) produced a string with two backslashes instead of one, in a departure from the behavior in previous versions. The older behavior has been reinstated. .IP "\fIcaller()\fR" 4 .IX Item "caller()" \&\fIcaller()\fR could cause core dumps in certain situations. Carp was sometimes affected by this problem. .IP "Bugs in regular expressions" 4 .IX Item "Bugs in regular expressions" Pattern matches on overloaded values are now handled correctly. .Sp Perl 5.6.0 parsed m/\ex{ab}/ incorrectly, leading to spurious warnings. This has been corrected. .Sp The \s-1RE\s0 engine found in Perl 5.6.0 accidentally pessimised certain kinds of simple pattern matches. These are now handled better. .Sp Regular expression debug output (whether through \f(CW\*(C`use re \*(Aqdebug\*(Aq\*(C'\fR or via \f(CW\*(C`\-Dr\*(C'\fR) now looks better. .Sp Multi-line matches like \f(CW\*(C`"a\enxb\en" =~ /(?!\eA)x/m\*(C'\fR were flawed. The bug has been fixed. .Sp Use of $& could trigger a core dump under some situations. This is now avoided. .Sp Match variables \f(CW$1\fR et al., weren't being unset when a pattern match was backtracking, and the anomaly showed up inside \f(CW\*(C`/...(?{ ... }).../\*(C'\fR etc. These variables are now tracked correctly. .Sp \&\fIpos()\fR did not return the correct value within s///ge in earlier versions. This is now handled correctly. .ie n .IP """slurp"" mode" 4 .el .IP "``slurp'' mode" 4 .IX Item "slurp mode" \&\fIreadline()\fR on files opened in \*(L"slurp\*(R" mode could return an extra "" at the end in certain situations. This has been corrected. .IP "Autovivification of symbolic references to special variables" 4 .IX Item "Autovivification of symbolic references to special variables" Autovivification of symbolic references of special variables described in perlvar (as in \f(CW\*(C`${$num}\*(C'\fR) was accidentally disabled. This works again now. .IP "Lexical warnings" 4 .IX Item "Lexical warnings" Lexical warnings now propagate correctly into \f(CW\*(C`eval "..."\*(C'\fR. .Sp \&\f(CW\*(C`use warnings qw(FATAL all)\*(C'\fR did not work as intended. This has been corrected. .Sp Lexical warnings could leak into other scopes in some situations. This is now fixed. .Sp \&\fIwarnings::enabled()\fR now reports the state of $^W correctly if the caller isn't using lexical warnings. .IP "Spurious warnings and errors" 4 .IX Item "Spurious warnings and errors" Perl 5.6.0 could emit spurious warnings about redefinition of \fIdl_error()\fR when statically building extensions into perl. This has been corrected. .Sp \&\*(L"our\*(R" variables could result in bogus \*(L"Variable will not stay shared\*(R" warnings. This is now fixed. .Sp \&\*(L"our\*(R" variables of the same name declared in two sibling blocks resulted in bogus warnings about \*(L"redeclaration\*(R" of the variables. The problem has been corrected. .IP "\fIglob()\fR" 4 .IX Item "glob()" Compatibility of the builtin \fIglob()\fR with old csh-based glob has been improved with the addition of \s-1GLOB_ALPHASORT\s0 option. See \f(CW\*(C`File::Glob\*(C'\fR. .Sp \&\fIFile::Glob::glob()\fR has been renamed to \fIFile::Glob::bsd_glob()\fR because the name clashes with the builtin \fIglob()\fR. The older name is still available for compatibility, but is deprecated. .Sp Spurious syntax errors generated in certain situations, when \fIglob()\fR caused File::Glob to be loaded for the first time, have been fixed. .IP "Tainting" 4 .IX Item "Tainting" Some cases of inconsistent taint propagation (such as within hash values) have been fixed. .Sp The tainting behavior of \fIsprintf()\fR has been rationalized. It does not taint the result of floating point formats anymore, making the behavior consistent with that of string interpolation. .IP "\fIsort()\fR" 4 .IX Item "sort()" Arguments to \fIsort()\fR weren't being provided the right \fIwantarray()\fR context. The comparison block is now run in scalar context, and the arguments to be sorted are always provided list context. .Sp \&\fIsort()\fR is also fully reentrant, in the sense that the sort function can itself call \fIsort()\fR. This did not work reliably in previous releases. .IP "#line directives" 4 .IX Item "#line directives" #line directives now work correctly when they appear at the very beginning of \f(CW\*(C`eval "..."\*(C'\fR. .IP "Subroutine prototypes" 4 .IX Item "Subroutine prototypes" The (\e&) prototype now works properly. .IP "\fImap()\fR" 4 .IX Item "map()" \&\fImap()\fR could get pathologically slow when the result list it generates is larger than the source list. The performance has been improved for common scenarios. .IP "Debugger" 4 .IX Item "Debugger" Debugger exit code now reflects the script exit code. .Sp Condition \f(CW"0"\fR in breakpoints is now treated correctly. .Sp The \f(CW\*(C`d\*(C'\fR command now checks the line number. .Sp \&\f(CW$.\fR is no longer corrupted by the debugger. .Sp All debugger output now correctly goes to the socket if RemotePort is set. .IP "\s-1PERL5OPT\s0" 4 .IX Item "PERL5OPT" \&\s-1PERL5OPT\s0 can be set to more than one switch group. Previously, it used to be limited to one group of options only. .IP "\fIchop()\fR" 4 .IX Item "chop()" chop(@list) in list context returned the characters chopped in reverse order. This has been reversed to be in the right order. .IP "Unicode support" 4 .IX Item "Unicode support" Unicode support has seen a large number of incremental improvements, but continues to be highly experimental. It is not expected to be fully supported in the 5.6.x maintenance releases. .Sp \&\fIsubstr()\fR, \fIjoin()\fR, \fIrepeat()\fR, \fIreverse()\fR, \fIquotemeta()\fR and string concatenation were all handling Unicode strings incorrectly in Perl 5.6.0. This has been corrected. .Sp Support for \f(CW\*(C`tr///CU\*(C'\fR and \f(CW\*(C`tr///UC\*(C'\fR etc., have been removed since we realized the interface is broken. For similar functionality, see \*(L"pack\*(R" in perlfunc. .Sp The Unicode Character Database has been updated to version 3.0.1 with additions made available to the public as of August 30, 2000. .Sp The Unicode character classes \ep{Blank} and \ep{SpacePerl} have been added. \*(L"Blank\*(R" is like C \fIisblank()\fR, that is, it contains only \&\*(L"horizontal whitespace\*(R" (the space character is, the newline isn't), and the \*(L"SpacePerl\*(R" is the Unicode equivalent of \f(CW\*(C`\es\*(C'\fR (\ep{Space} isn't, since that includes the vertical tabulator character, whereas \&\f(CW\*(C`\es\*(C'\fR doesn't.) .Sp If you are experimenting with Unicode support in perl, the development versions of Perl may have more to offer. In particular, I/O layers are now available in the development track, but not in the maintenance track, primarily to do backward compatibility issues. Unicode support is also evolving rapidly on a daily basis in the development track\*(--the maintenance track only reflects the most conservative of these changes. .IP "64\-bit support" 4 .IX Item "64-bit support" Support for 64\-bit platforms has been improved, but continues to be experimental. The level of support varies greatly among platforms. .IP "Compiler" 4 .IX Item "Compiler" The B Compiler and its various backends have had many incremental improvements, but they continue to remain highly experimental. Use in production environments is discouraged. .Sp The perlcc tool has been rewritten so that the user interface is much more like that of a C compiler. .Sp The perlbc tools has been removed. Use \f(CW\*(C`perlcc \-B\*(C'\fR instead. .IP "Lvalue subroutines" 4 .IX Item "Lvalue subroutines" There have been various bugfixes to support lvalue subroutines better. However, the feature still remains experimental. .IP "IO::Socket" 4 .IX Item "IO::Socket" IO::Socket::INET failed to open the specified port if the service name was not known. It now correctly uses the supplied port number as is. .IP "File::Find" 4 .IX Item "File::Find" File::Find now \fIchdir()\fRs correctly when chasing symbolic links. .IP "xsubpp" 4 .IX Item "xsubpp" xsubpp now tolerates embedded \s-1POD\s0 sections. .ie n .IP """no Module;""" 4 .el .IP "\f(CWno Module;\fR" 4 .IX Item "no Module;" \&\f(CW\*(C`no Module;\*(C'\fR does not produce an error even if Module does not have an \&\fIunimport()\fR method. This parallels the behavior of \f(CW\*(C`use\*(C'\fR vis-a-vis \&\f(CW\*(C`import\*(C'\fR. .IP "Tests" 4 .IX Item "Tests" A large number of tests have been added. .SS "Core features" .IX Subsection "Core features" \&\fIuntie()\fR will now call an \s-1\fIUNTIE\s0()\fR hook if it exists. See perltie for details. .PP The \f(CW\*(C`\-DT\*(C'\fR command line switch outputs copious tokenizing information. See perlrun. .PP Arrays are now always interpolated in double-quotish strings. Previously, \&\f(CW"foo@bar.com"\fR used to be a fatal error at compile time, if an array \&\f(CW@bar\fR was not used or declared. This transitional behavior was intended to help migrate perl4 code, and is deemed to be no longer useful. See \*(L"Arrays now always interpolate into double-quoted strings\*(R". .PP \&\fIkeys()\fR, \fIeach()\fR, \fIpop()\fR, \fIpush()\fR, \fIshift()\fR, \fIsplice()\fR and \fIunshift()\fR can all be overridden now. .PP \&\f(CW\*(C`my _\|_PACKAGE_\|_ $obj\*(C'\fR now does the expected thing. .SS "Configuration issues" .IX Subsection "Configuration issues" On some systems (\s-1IRIX\s0 and Solaris among them) the system malloc is demonstrably better. While the defaults haven't been changed in order to retain binary compatibility with earlier releases, you may be better off building perl with \f(CW\*(C`Configure \-Uusemymalloc ...\*(C'\fR as discussed in the \fI\s-1INSTALL\s0\fR file. .PP \&\f(CW\*(C`Configure\*(C'\fR has been enhanced in various ways: .IP "\(bu" 4 Minimizes use of temporary files. .IP "\(bu" 4 By default, does not link perl with libraries not used by it, such as the various dbm libraries. SunOS 4.x hints preserve behavior on that platform. .IP "\(bu" 4 Support for pdp11\-style memory models has been removed due to obsolescence. .IP "\(bu" 4 Building outside the source tree is supported on systems that have symbolic links. This is done by running .Sp .Vb 2 \& sh /path/to/source/Configure \-Dmksymlinks ... \& make all test install .Ve .Sp in a directory other than the perl source directory. See \fI\s-1INSTALL\s0\fR. .IP "\(bu" 4 \&\f(CW\*(C`Configure \-S\*(C'\fR can be run non-interactively. .SS "Documentation" .IX Subsection "Documentation" \&\s-1README\s0.aix, \s-1README\s0.solaris and \s-1README\s0.macos have been added. \&\s-1README\s0.posix\-bc has been renamed to \s-1README\s0.bs2000. These are installed as perlaix, perlsolaris, perlmacos, and perlbs2000 respectively. .PP The following pod documents are brand new: .PP .Vb 7 \& perlclib Internal replacements for standard C library functions \& perldebtut Perl debugging tutorial \& perlebcdic Considerations for running Perl on EBCDIC platforms \& perlnewmod Perl modules: preparing a new module for distribution \& perlrequick Perl regular expressions quick start \& perlretut Perl regular expressions tutorial \& perlutil utilities packaged with the Perl distribution .Ve .PP The \fI\s-1INSTALL\s0\fR file has been expanded to cover various issues, such as 64\-bit support. .PP A longer list of contributors has been added to the source distribution. See the file \f(CW\*(C`AUTHORS\*(C'\fR. .PP Numerous other changes have been made to the included documentation and FAQs. .SS "Bundled modules" .IX Subsection "Bundled modules" The following modules have been added. .IP "B::Concise" 4 .IX Item "B::Concise" Walks Perl syntax tree, printing concise info about ops. See B::Concise. .IP "File::Temp" 4 .IX Item "File::Temp" Returns name and handle of a temporary file safely. See File::Temp. .IP "Pod::LaTeX" 4 .IX Item "Pod::LaTeX" Converts Pod data to formatted LaTeX. See Pod::LaTeX. .IP "Pod::Text::Overstrike" 4 .IX Item "Pod::Text::Overstrike" Converts \s-1POD\s0 data to formatted overstrike text. See Pod::Text::Overstrike. .PP The following modules have been upgraded. .IP "\s-1CGI\s0" 4 .IX Item "CGI" \&\s-1CGI\s0 v2.752 is now included. .IP "\s-1CPAN\s0" 4 .IX Item "CPAN" \&\s-1CPAN\s0 v1.59_54 is now included. .IP "Class::Struct" 4 .IX Item "Class::Struct" Various bugfixes have been added. .IP "DB_File" 4 .IX Item "DB_File" DB_File v1.75 supports newer Berkeley \s-1DB\s0 versions, among other improvements. .IP "Devel::Peek" 4 .IX Item "Devel::Peek" Devel::Peek has been enhanced to support dumping of memory statistics, when perl is built with the included \fImalloc()\fR. .IP "File::Find" 4 .IX Item "File::Find" File::Find now supports pre and post-processing of the files in order to \fIsort()\fR them, etc. .IP "Getopt::Long" 4 .IX Item "Getopt::Long" Getopt::Long v2.25 is included. .IP "IO::Poll" 4 .IX Item "IO::Poll" Various bug fixes have been included. .IP "IPC::Open3" 4 .IX Item "IPC::Open3" IPC::Open3 allows use of numeric file descriptors. .IP "Math::BigFloat" 4 .IX Item "Math::BigFloat" The \fIfmod()\fR function supports modulus operations. Various bug fixes have also been included. .IP "Math::Complex" 4 .IX Item "Math::Complex" Math::Complex handles inf, NaN etc., better. .IP "Net::Ping" 4 .IX Item "Net::Ping" \&\fIping()\fR could fail on odd number of data bytes, and when the echo service isn't running. This has been corrected. .IP "Opcode" 4 .IX Item "Opcode" A memory leak has been fixed. .IP "Pod::Parser" 4 .IX Item "Pod::Parser" Version 1.13 of the Pod::Parser suite is included. .IP "Pod::Text" 4 .IX Item "Pod::Text" Pod::Text and related modules have been upgraded to the versions in podlators suite v2.08. .IP "SDBM_File" 4 .IX Item "SDBM_File" On dosish platforms, some keys went missing because of lack of support for files with \*(L"holes\*(R". A workaround for the problem has been added. .IP "Sys::Syslog" 4 .IX Item "Sys::Syslog" Various bug fixes have been included. .IP "Tie::RefHash" 4 .IX Item "Tie::RefHash" Now supports Tie::RefHash::Nestable to automagically tie hashref values. .IP "Tie::SubstrHash" 4 .IX Item "Tie::SubstrHash" Various bug fixes have been included. .SS "Platform-specific improvements" .IX Subsection "Platform-specific improvements" The following new ports are now available. .IP "\s-1NCR\s0 MP-RAS" 4 .IX Item "NCR MP-RAS" .PD 0 .IP "NonStop-UX" 4 .IX Item "NonStop-UX" .PD .PP Perl now builds under Amdahl \s-1UTS\s0. .PP Perl has also been verified to build under Amiga \s-1OS\s0. .PP Support for \s-1EPOC\s0 has been much improved. See \s-1README\s0.epoc. .PP Building perl with \-Duseithreads or \-Duse5005threads now works under HP-UX 10.20 (previously it only worked under 10.30 or later). You will need a thread library package installed. See \s-1README\s0.hpux. .PP Long doubles should now work under Linux. .PP Mac \s-1OS\s0 Classic is now supported in the mainstream source package. See \s-1README\s0.macos. .PP Support for MPE/iX has been updated. See \s-1README\s0.mpeix. .PP Support for \s-1OS/2\s0 has been improved. See \f(CW\*(C`os2/Changes\*(C'\fR and \s-1README\s0.os2. .PP Dynamic loading on z/OS (formerly \s-1OS/390\s0) has been improved. See \&\s-1README\s0.os390. .PP Support for \s-1VMS\s0 has seen many incremental improvements, including better support for operators like backticks and \fIsystem()\fR, and better \&\f(CW%ENV\fR handling. See \f(CW\*(C`README.vms\*(C'\fR and perlvms. .PP Support for Stratus \s-1VOS\s0 has been improved. See \f(CW\*(C`vos/Changes\*(C'\fR and \s-1README\s0.vos. .PP Support for Windows has been improved. .IP "\(bu" 4 \&\fIfork()\fR emulation has been improved in various ways, but still continues to be experimental. See perlfork for known bugs and caveats. .IP "\(bu" 4 \&\f(CW%SIG\fR has been enabled under \s-1USE_ITHREADS\s0, but its use is completely unsupported under all configurations. .IP "\(bu" 4 Borland \*(C+ v5.5 is now a supported compiler that can build Perl. However, the generated binaries continue to be incompatible with those generated by the other supported compilers (\s-1GCC\s0 and Visual \*(C+). .IP "\(bu" 4 Non-blocking waits for child processes (or pseudo-processes) are supported via \f(CW\*(C`waitpid($pid, &POSIX::WNOHANG)\*(C'\fR. .IP "\(bu" 4 A memory leak in \fIaccept()\fR has been fixed. .IP "\(bu" 4 \&\fIwait()\fR, \fIwaitpid()\fR and backticks now return the correct exit status under Windows 9x. .IP "\(bu" 4 Trailing new \f(CW%ENV\fR entries weren't propagated to child processes. This is now fixed. .IP "\(bu" 4 Current directory entries in \f(CW%ENV\fR are now correctly propagated to child processes. .IP "\(bu" 4 Duping socket handles with open(F, \*(L">&MYSOCK\*(R") now works under Windows 9x. .IP "\(bu" 4 The makefiles now provide a single switch to bulk-enable all the features enabled in ActiveState ActivePerl (a popular binary distribution). .IP "\(bu" 4 \&\fIWin32::GetCwd()\fR correctly returns C:\e instead of C: when at the drive root. Other bugs in \fIchdir()\fR and \fICwd::cwd()\fR have also been fixed. .IP "\(bu" 4 \&\fIfork()\fR correctly returns undef and sets \s-1EAGAIN\s0 when it runs out of pseudo-process handles. .IP "\(bu" 4 ExtUtils::MakeMaker now uses \f(CW$ENV\fR{\s-1LIB\s0} to search for libraries. .IP "\(bu" 4 \&\s-1UNC\s0 path handling is better when perl is built to support \fIfork()\fR. .IP "\(bu" 4 A handle leak in socket handling has been fixed. .IP "\(bu" 4 \&\fIsend()\fR works from within a pseudo-process. .PP Unless specifically qualified otherwise, the remainder of this document covers changes between the 5.005 and 5.6.0 releases. .SH "Core Enhancements" .IX Header "Core Enhancements" .SS "Interpreter cloning, threads, and concurrency" .IX Subsection "Interpreter cloning, threads, and concurrency" Perl 5.6.0 introduces the beginnings of support for running multiple interpreters concurrently in different threads. In conjunction with the \fIperl_clone()\fR \s-1API\s0 call, which can be used to selectively duplicate the state of any given interpreter, it is possible to compile a piece of code once in an interpreter, clone that interpreter one or more times, and run all the resulting interpreters in distinct threads. .PP On the Windows platform, this feature is used to emulate \fIfork()\fR at the interpreter level. See perlfork for details about that. .PP This feature is still in evolution. It is eventually meant to be used to selectively clone a subroutine and data reachable from that subroutine in a separate interpreter and run the cloned subroutine in a separate thread. Since there is no shared data between the interpreters, little or no locking will be needed (unless parts of the symbol table are explicitly shared). This is obviously intended to be an easy-to-use replacement for the existing threads support. .PP Support for cloning interpreters and interpreter concurrency can be enabled using the \-Dusethreads Configure option (see win32/Makefile for how to enable it on Windows.) The resulting perl executable will be functionally identical to one that was built with \-Dmultiplicity, but the \fIperl_clone()\fR \s-1API\s0 call will only be available in the former. .PP \&\-Dusethreads enables the cpp macro \s-1USE_ITHREADS\s0 by default, which in turn enables Perl source code changes that provide a clear separation between the op tree and the data it operates with. The former is immutable, and can therefore be shared between an interpreter and all of its clones, while the latter is considered local to each interpreter, and is therefore copied for each clone. .PP Note that building Perl with the \-Dusemultiplicity Configure option is adequate if you wish to run multiple \fBindependent\fR interpreters concurrently in different threads. \-Dusethreads only provides the additional functionality of the \fIperl_clone()\fR \s-1API\s0 call and other support for running \fBcloned\fR interpreters concurrently. .PP .Vb 2 \& NOTE: This is an experimental feature. Implementation details are \& subject to change. .Ve .SS "Lexically scoped warning categories" .IX Subsection "Lexically scoped warning categories" You can now control the granularity of warnings emitted by perl at a finer level using the \f(CW\*(C`use warnings\*(C'\fR pragma. warnings and perllexwarn have copious documentation on this feature. .SS "Unicode and \s-1UTF\-8\s0 support" .IX Subsection "Unicode and UTF-8 support" Perl now uses \s-1UTF\-8\s0 as its internal representation for character strings. The \f(CW\*(C`utf8\*(C'\fR and \f(CW\*(C`bytes\*(C'\fR pragmas are used to control this support in the current lexical scope. See perlunicode, utf8 and bytes for more information. .PP This feature is expected to evolve quickly to support some form of I/O disciplines that can be used to specify the kind of input and output data (bytes or characters). Until that happens, additional modules from \s-1CPAN\s0 will be needed to complete the toolkit for dealing with Unicode. .PP .Vb 2 \& NOTE: This should be considered an experimental feature. Implementation \& details are subject to change. .Ve .SS "Support for interpolating named characters" .IX Subsection "Support for interpolating named characters" The new \f(CW\*(C`\eN\*(C'\fR escape interpolates named characters within strings. For example, \f(CW"Hi! \eN{WHITE SMILING FACE}"\fR evaluates to a string with a Unicode smiley face at the end. .ie n .SS """our"" declarations" .el .SS "``our'' declarations" .IX Subsection "our declarations" An \*(L"our\*(R" declaration introduces a value that can be best understood as a lexically scoped symbolic alias to a global variable in the package that was current where the variable was declared. This is mostly useful as an alternative to the \f(CW\*(C`vars\*(C'\fR pragma, but also provides the opportunity to introduce typing and other attributes for such variables. See \*(L"our\*(R" in perlfunc. .SS "Support for strings represented as a vector of ordinals" .IX Subsection "Support for strings represented as a vector of ordinals" Literals of the form \f(CW\*(C`v1.2.3.4\*(C'\fR are now parsed as a string composed of characters with the specified ordinals. This is an alternative, more readable way to construct (possibly Unicode) strings instead of interpolating characters, as in \f(CW"\ex{1}\ex{2}\ex{3}\ex{4}"\fR. The leading \&\f(CW\*(C`v\*(C'\fR may be omitted if there are more than two ordinals, so \f(CW1.2.3\fR is parsed the same as \f(CW\*(C`v1.2.3\*(C'\fR. .PP Strings written in this form are also useful to represent version \*(L"numbers\*(R". It is easy to compare such version \*(L"numbers\*(R" (which are really just plain strings) using any of the usual string comparison operators \f(CW\*(C`eq\*(C'\fR, \f(CW\*(C`ne\*(C'\fR, \&\f(CW\*(C`lt\*(C'\fR, \f(CW\*(C`gt\*(C'\fR, etc., or perform bitwise string operations on them using \f(CW\*(C`|\*(C'\fR, \&\f(CW\*(C`&\*(C'\fR, etc. .PP In conjunction with the new \f(CW$^V\fR magic variable (which contains the perl version as a string), such literals can be used as a readable way to check if you're running a particular version of Perl: .PP .Vb 4 \& # this will parse in older versions of Perl also \& if ($^V and $^V gt v5.6.0) { \& # new features supported \& } .Ve .PP \&\f(CW\*(C`require\*(C'\fR and \f(CW\*(C`use\*(C'\fR also have some special magic to support such literals. They will be interpreted as a version rather than as a module name: .PP .Vb 2 \& require v5.6.0; # croak if $^V lt v5.6.0 \& use v5.6.0; # same, but croaks at compile\-time .Ve .PP Alternatively, the \f(CW\*(C`v\*(C'\fR may be omitted if there is more than one dot: .PP .Vb 2 \& require 5.6.0; \& use 5.6.0; .Ve .PP Also, \f(CW\*(C`sprintf\*(C'\fR and \f(CW\*(C`printf\*(C'\fR support the Perl-specific format flag \f(CW%v\fR to print ordinals of characters in arbitrary strings: .PP .Vb 3 \& printf "v%vd", $^V; # prints current version, such as "v5.5.650" \& printf "%*vX", ":", $addr; # formats IPv6 address \& printf "%*vb", " ", $bits; # displays bitstring .Ve .PP See \*(L"Scalar value constructors\*(R" in perldata for additional information. .SS "Improved Perl version numbering system" .IX Subsection "Improved Perl version numbering system" Beginning with Perl version 5.6.0, the version number convention has been changed to a \*(L"dotted integer\*(R" scheme that is more commonly found in open source projects. .PP Maintenance versions of v5.6.0 will be released as v5.6.1, v5.6.2 etc. The next development series following v5.6.0 will be numbered v5.7.x, beginning with v5.7.0, and the next major production release following v5.6.0 will be v5.8.0. .PP The English module now sets \f(CW$PERL_VERSION\fR to $^V (a string value) rather than \f(CW$]\fR (a numeric value). (This is a potential incompatibility. Send us a report via perlbug if you are affected by this.) .PP The v1.2.3 syntax is also now legal in Perl. See \*(L"Support for strings represented as a vector of ordinals\*(R" for more on that. .PP To cope with the new versioning system's use of at least three significant digits for each version component, the method used for incrementing the subversion number has also changed slightly. We assume that versions older than v5.6.0 have been incrementing the subversion component in multiples of 10. Versions after v5.6.0 will increment them by 1. Thus, using the new notation, 5.005_03 is the \*(L"same\*(R" as v5.5.30, and the first maintenance version following v5.6.0 will be v5.6.1 (which should be read as being equivalent to a floating point value of 5.006_001 in the older format, stored in \f(CW$]\fR). .SS "New syntax for declaring subroutine attributes" .IX Subsection "New syntax for declaring subroutine attributes" Formerly, if you wanted to mark a subroutine as being a method call or as requiring an automatic \fIlock()\fR when it is entered, you had to declare that with a \f(CW\*(C`use attrs\*(C'\fR pragma in the body of the subroutine. That can now be accomplished with declaration syntax, like this: .PP .Vb 5 \& sub mymethod : locked method; \& ... \& sub mymethod : locked method { \& ... \& } \& \& sub othermethod :locked :method; \& ... \& sub othermethod :locked :method { \& ... \& } .Ve .PP (Note how only the first \f(CW\*(C`:\*(C'\fR is mandatory, and whitespace surrounding the \f(CW\*(C`:\*(C'\fR is optional.) .PP \&\fIAutoSplit.pm\fR and \fISelfLoader.pm\fR have been updated to keep the attributes with the stubs they provide. See attributes. .SS "File and directory handles can be autovivified" .IX Subsection "File and directory handles can be autovivified" Similar to how constructs such as \f(CW\*(C`$x\->[0]\*(C'\fR autovivify a reference, handle constructors (\fIopen()\fR, \fIopendir()\fR, \fIpipe()\fR, \fIsocketpair()\fR, \fIsysopen()\fR, \&\fIsocket()\fR, and \fIaccept()\fR) now autovivify a file or directory handle if the handle passed to them is an uninitialized scalar variable. This allows the constructs such as \f(CW\*(C`open(my $fh, ...)\*(C'\fR and \f(CW\*(C`open(local $fh,...)\*(C'\fR to be used to create filehandles that will conveniently be closed automatically when the scope ends, provided there are no other references to them. This largely eliminates the need for typeglobs when opening filehandles that must be passed around, as in the following example: .PP .Vb 5 \& sub myopen { \& open my $fh, "@_" \& or die "Can\*(Aqt open \*(Aq@_\*(Aq: $!"; \& return $fh; \& } \& \& { \& my $f = myopen("</etc/motd"); \& print <$f>; \& # $f implicitly closed here \& } .Ve .SS "\fIopen()\fP with more than two arguments" .IX Subsection "open() with more than two arguments" If \fIopen()\fR is passed three arguments instead of two, the second argument is used as the mode and the third argument is taken to be the file name. This is primarily useful for protecting against unintended magic behavior of the traditional two-argument form. See \*(L"open\*(R" in perlfunc. .SS "64\-bit support" .IX Subsection "64-bit support" Any platform that has 64\-bit integers either .PP .Vb 3 \& (1) natively as longs or ints \& (2) via special compiler flags \& (3) using long long or int64_t .Ve .PP is able to use \*(L"quads\*(R" (64\-bit integers) as follows: .IP "\(bu" 4 constants (decimal, hexadecimal, octal, binary) in the code .IP "\(bu" 4 arguments to \fIoct()\fR and \fIhex()\fR .IP "\(bu" 4 arguments to \fIprint()\fR, \fIprintf()\fR and \fIsprintf()\fR (flag prefixes ll, L, q) .IP "\(bu" 4 printed as such .IP "\(bu" 4 \&\fIpack()\fR and \fIunpack()\fR \*(L"q\*(R" and \*(L"Q\*(R" formats .IP "\(bu" 4 in basic arithmetics: + \- * / % (\s-1NOTE:\s0 operating close to the limits of the integer values may produce surprising results) .IP "\(bu" 4 in bit arithmetics: & | ^ ~ << >> (\s-1NOTE:\s0 these used to be forced to be 32 bits wide but now operate on the full native width.) .IP "\(bu" 4 \&\fIvec()\fR .PP Note that unless you have the case (a) you will have to configure and compile Perl using the \-Duse64bitint Configure flag. .PP .Vb 2 \& NOTE: The Configure flags \-Duselonglong and \-Duse64bits have been \& deprecated. Use \-Duse64bitint instead. .Ve .PP There are actually two modes of 64\-bitness: the first one is achieved using Configure \-Duse64bitint and the second one using Configure \&\-Duse64bitall. The difference is that the first one is minimal and the second one maximal. The first works in more places than the second. .PP The \f(CW\*(C`use64bitint\*(C'\fR does only as much as is required to get 64\-bit integers into Perl (this may mean, for example, using \*(L"long longs\*(R") while your memory may still be limited to 2 gigabytes (because your pointers could still be 32\-bit). Note that the name \f(CW\*(C`64bitint\*(C'\fR does not imply that your C compiler will be using 64\-bit \f(CW\*(C`int\*(C'\fRs (it might, but it doesn't have to): the \f(CW\*(C`use64bitint\*(C'\fR means that you will be able to have 64 bits wide scalar values. .PP The \f(CW\*(C`use64bitall\*(C'\fR goes all the way by attempting to switch also integers (if it can), longs (and pointers) to being 64\-bit. This may create an even more binary incompatible Perl than \-Duse64bitint: the resulting executable may not run at all in a 32\-bit box, or you may have to reboot/reconfigure/rebuild your operating system to be 64\-bit aware. .PP Natively 64\-bit systems like Alpha and Cray need neither \-Duse64bitint nor \-Duse64bitall. .PP Last but not least: note that due to Perl's habit of always using floating point numbers, the quads are still not true integers. When quads overflow their limits (0...18_446_744_073_709_551_615 unsigned, \&\-9_223_372_036_854_775_808...9_223_372_036_854_775_807 signed), they are silently promoted to floating point numbers, after which they will start losing precision (in their lower digits). .PP .Vb 4 \& NOTE: 64\-bit support is still experimental on most platforms. \& Existing support only covers the LP64 data model. In particular, the \& LLP64 data model is not yet supported. 64\-bit libraries and system \& APIs on many platforms have not stabilized\-\-your mileage may vary. .Ve .SS "Large file support" .IX Subsection "Large file support" If you have filesystems that support \*(L"large files\*(R" (files larger than 2 gigabytes), you may now also be able to create and access them from Perl. .PP .Vb 2 \& NOTE: The default action is to enable large file support, if \& available on the platform. .Ve .PP If the large file support is on, and you have a Fcntl constant O_LARGEFILE, the O_LARGEFILE is automatically added to the flags of \fIsysopen()\fR. .PP Beware that unless your filesystem also supports \*(L"sparse files\*(R" seeking to umpteen petabytes may be inadvisable. .PP Note that in addition to requiring a proper file system to do large files you may also need to adjust your per-process (or your per-system, or per-process-group, or per-user-group) maximum filesize limits before running Perl scripts that try to handle large files, especially if you intend to write such files. .PP Finally, in addition to your process/process group maximum filesize limits, you may have quota limits on your filesystems that stop you (your user id or your user group id) from using large files. .PP Adjusting your process/user/group/file system/operating system limits is outside the scope of Perl core language. For process limits, you may try increasing the limits using your shell's limits/limit/ulimit command before running Perl. The BSD::Resource extension (not included with the standard Perl distribution) may also be of use, it offers the getrlimit/setrlimit interface that can be used to adjust process resource usage limits, including the maximum filesize limit. .SS "Long doubles" .IX Subsection "Long doubles" In some systems you may be able to use long doubles to enhance the range and precision of your double precision floating point numbers (that is, Perl's numbers). Use Configure \-Duselongdouble to enable this support (if it is available). .ie n .SS """more bits""" .el .SS "``more bits''" .IX Subsection "more bits" You can \*(L"Configure \-Dusemorebits\*(R" to turn on both the 64\-bit support and the long double support. .SS "Enhanced support for \fIsort()\fP subroutines" .IX Subsection "Enhanced support for sort() subroutines" Perl subroutines with a prototype of \f(CW\*(C`($$)\*(C'\fR, and XSUBs in general, can now be used as sort subroutines. In either case, the two elements to be compared are passed as normal parameters in \f(CW@_\fR. See \*(L"sort\*(R" in perlfunc. .PP For unprototyped sort subroutines, the historical behavior of passing the elements to be compared as the global variables \f(CW$a\fR and \f(CW$b\fR remains unchanged. .ie n .SS """sort $coderef @foo"" allowed" .el .SS "\f(CWsort $coderef @foo\fP allowed" .IX Subsection "sort $coderef @foo allowed" \&\fIsort()\fR did not accept a subroutine reference as the comparison function in earlier versions. This is now permitted. .SS "File globbing implemented internally" .IX Subsection "File globbing implemented internally" Perl now uses the File::Glob implementation of the \fIglob()\fR operator automatically. This avoids using an external csh process and the problems associated with it. .PP .Vb 2 \& NOTE: This is currently an experimental feature. Interfaces and \& implementation are subject to change. .Ve .SS "Support for \s-1CHECK\s0 blocks" .IX Subsection "Support for CHECK blocks" In addition to \f(CW\*(C`BEGIN\*(C'\fR, \f(CW\*(C`INIT\*(C'\fR, \f(CW\*(C`END\*(C'\fR, \f(CW\*(C`DESTROY\*(C'\fR and \f(CW\*(C`AUTOLOAD\*(C'\fR, subroutines named \f(CW\*(C`CHECK\*(C'\fR are now special. These are queued up during compilation and behave similar to \s-1END\s0 blocks, except they are called at the end of compilation rather than at the end of execution. They cannot be called directly. .SS "\s-1POSIX\s0 character class syntax [: :] supported" .IX Subsection "POSIX character class syntax [: :] supported" For example to match alphabetic characters use /[[:alpha:]]/. See perlre for details. .SS "Better pseudo-random number generator" .IX Subsection "Better pseudo-random number generator" In 5.005_0x and earlier, perl's \fIrand()\fR function used the C library \&\fIrand\fR\|(3) function. As of 5.005_52, Configure tests for \fIdrand48()\fR, \&\fIrandom()\fR, and \fIrand()\fR (in that order) and picks the first one it finds. .PP These changes should result in better random numbers from \fIrand()\fR. .ie n .SS "Improved ""qw//"" operator" .el .SS "Improved \f(CWqw//\fP operator" .IX Subsection "Improved qw// operator" The \f(CW\*(C`qw//\*(C'\fR operator is now evaluated at compile time into a true list instead of being replaced with a run time call to \f(CW\*(C`split()\*(C'\fR. This removes the confusing misbehaviour of \f(CW\*(C`qw//\*(C'\fR in scalar context, which had inherited that behaviour from \fIsplit()\fR. .PP Thus: .PP .Vb 1 \& $foo = ($bar) = qw(a b c); print "$foo|$bar\en"; .Ve .PP now correctly prints \*(L"3|a\*(R", instead of \*(L"2|a\*(R". .SS "Better worst-case behavior of hashes" .IX Subsection "Better worst-case behavior of hashes" Small changes in the hashing algorithm have been implemented in order to improve the distribution of lower order bits in the hashed value. This is expected to yield better performance on keys that are repeated sequences. .SS "\fIpack()\fP format 'Z' supported" .IX Subsection "pack() format 'Z' supported" The new format type 'Z' is useful for packing and unpacking null-terminated strings. See \*(L"pack\*(R" in perlfunc. .SS "\fIpack()\fP format modifier '!' supported" .IX Subsection "pack() format modifier '!' supported" The new format type modifier '!' is useful for packing and unpacking native shorts, ints, and longs. See \*(L"pack\*(R" in perlfunc. .SS "\fIpack()\fP and \fIunpack()\fP support counted strings" .IX Subsection "pack() and unpack() support counted strings" The template character '/' can be used to specify a counted string type to be packed or unpacked. See \*(L"pack\*(R" in perlfunc. .SS "Comments in \fIpack()\fP templates" .IX Subsection "Comments in pack() templates" The '#' character in a template introduces a comment up to end of the line. This facilitates documentation of \fIpack()\fR templates. .SS "Weak references" .IX Subsection "Weak references" In previous versions of Perl, you couldn't cache objects so as to allow them to be deleted if the last reference from outside the cache is deleted. The reference in the cache would hold a reference count on the object and the objects would never be destroyed. .PP Another familiar problem is with circular references. When an object references itself, its reference count would never go down to zero, and it would not get destroyed until the program is about to exit. .PP Weak references solve this by allowing you to \*(L"weaken\*(R" any reference, that is, make it not count towards the reference count. When the last non-weak reference to an object is deleted, the object is destroyed and all the weak references to the object are automatically undef-ed. .PP To use this feature, you need the Devel::WeakRef package from \s-1CPAN\s0, which contains additional documentation. .PP .Vb 1 \& NOTE: This is an experimental feature. Details are subject to change. .Ve .SS "Binary numbers supported" .IX Subsection "Binary numbers supported" Binary numbers are now supported as literals, in s?printf formats, and \&\f(CW\*(C`oct()\*(C'\fR: .PP .Vb 2 \& $answer = 0b101010; \& printf "The answer is: %b\en", oct("0b101010"); .Ve .SS "Lvalue subroutines" .IX Subsection "Lvalue subroutines" Subroutines can now return modifiable lvalues. See \*(L"Lvalue subroutines\*(R" in perlsub. .PP .Vb 1 \& NOTE: This is an experimental feature. Details are subject to change. .Ve .SS "Some arrows may be omitted in calls through references" .IX Subsection "Some arrows may be omitted in calls through references" Perl now allows the arrow to be omitted in many constructs involving subroutine calls through references. For example, \&\f(CW\*(C`$foo[10]\->(\*(Aqfoo\*(Aq)\*(C'\fR may now be written \f(CW\*(C`$foo[10](\*(Aqfoo\*(Aq)\*(C'\fR. This is rather similar to how the arrow may be omitted from \&\f(CW\*(C`$foo[10]\->{\*(Aqfoo\*(Aq}\*(C'\fR. Note however, that the arrow is still required for \f(CW\*(C`foo(10)\->(\*(Aqbar\*(Aq)\*(C'\fR. .SS "Boolean assignment operators are legal lvalues" .IX Subsection "Boolean assignment operators are legal lvalues" Constructs such as \f(CW\*(C`($a ||= 2) += 1\*(C'\fR are now allowed. .SS "\fIexists()\fP is supported on subroutine names" .IX Subsection "exists() is supported on subroutine names" The \fIexists()\fR builtin now works on subroutine names. A subroutine is considered to exist if it has been declared (even if implicitly). See \*(L"exists\*(R" in perlfunc for examples. .SS "\fIexists()\fP and \fIdelete()\fP are supported on array elements" .IX Subsection "exists() and delete() are supported on array elements" The \fIexists()\fR and \fIdelete()\fR builtins now work on simple arrays as well. The behavior is similar to that on hash elements. .PP \&\fIexists()\fR can be used to check whether an array element has been initialized. This avoids autovivifying array elements that don't exist. If the array is tied, the \s-1\fIEXISTS\s0()\fR method in the corresponding tied package will be invoked. .PP \&\fIdelete()\fR may be used to remove an element from the array and return it. The array element at that position returns to its uninitialized state, so that testing for the same element with \fIexists()\fR will return false. If the element happens to be the one at the end, the size of the array also shrinks up to the highest element that tests true for \&\fIexists()\fR, or 0 if none such is found. If the array is tied, the \s-1\fIDELETE\s0()\fR method in the corresponding tied package will be invoked. .PP See \*(L"exists\*(R" in perlfunc and \*(L"delete\*(R" in perlfunc for examples. .SS "Pseudo-hashes work better" .IX Subsection "Pseudo-hashes work better" Dereferencing some types of reference values in a pseudo-hash, such as \f(CW\*(C`$ph\->{foo}[1]\*(C'\fR, was accidentally disallowed. This has been corrected. .PP When applied to a pseudo-hash element, \fIexists()\fR now reports whether the specified value exists, not merely if the key is valid. .PP \&\fIdelete()\fR now works on pseudo-hashes. When given a pseudo-hash element or slice it deletes the values corresponding to the keys (but not the keys themselves). See \*(L"Pseudo-hashes: Using an array as a hash\*(R" in perlref. .PP Pseudo-hash slices with constant keys are now optimized to array lookups at compile-time. .PP List assignments to pseudo-hash slices are now supported. .PP The \f(CW\*(C`fields\*(C'\fR pragma now provides ways to create pseudo-hashes, via \&\fIfields::new()\fR and \fIfields::phash()\fR. See fields. .PP .Vb 3 \& NOTE: The pseudo\-hash data type continues to be experimental. \& Limiting oneself to the interface elements provided by the \& fields pragma will provide protection from any future changes. .Ve .SS "Automatic flushing of output buffers" .IX Subsection "Automatic flushing of output buffers" \&\fIfork()\fR, \fIexec()\fR, \fIsystem()\fR, qx//, and pipe \fIopen()\fRs now flush buffers of all files opened for output when the operation was attempted. This mostly eliminates confusing buffering mishaps suffered by users unaware of how Perl internally handles I/O. .PP This is not supported on some platforms like Solaris where a suitably correct implementation of fflush(\s-1NULL\s0) isn't available. .SS "Better diagnostics on meaningless filehandle operations" .IX Subsection "Better diagnostics on meaningless filehandle operations" Constructs such as \f(CW\*(C`open(<FH>)\*(C'\fR and \f(CW\*(C`close(<FH>)\*(C'\fR are compile time errors. Attempting to read from filehandles that were opened only for writing will now produce warnings (just as writing to read-only filehandles does). .SS "Where possible, buffered data discarded from duped input filehandle" .IX Subsection "Where possible, buffered data discarded from duped input filehandle" \&\f(CW\*(C`open(NEW, "<&OLD")\*(C'\fR now attempts to discard any data that was previously read and buffered in \f(CW\*(C`OLD\*(C'\fR before duping the handle. On platforms where doing this is allowed, the next read operation on \f(CW\*(C`NEW\*(C'\fR will return the same data as the corresponding operation on \f(CW\*(C`OLD\*(C'\fR. Formerly, it would have returned the data from the start of the following disk block instead. .SS "\fIeof()\fP has the same old magic as <>" .IX Subsection "eof() has the same old magic as <>" \&\f(CW\*(C`eof()\*(C'\fR would return true if no attempt to read from \f(CW\*(C`<>\*(C'\fR had yet been made. \f(CW\*(C`eof()\*(C'\fR has been changed to have a little magic of its own, it now opens the \f(CW\*(C`<>\*(C'\fR files. .SS "\fIbinmode()\fP can be used to set :crlf and :raw modes" .IX Subsection "binmode() can be used to set :crlf and :raw modes" \&\fIbinmode()\fR now accepts a second argument that specifies a discipline for the handle in question. The two pseudo-disciplines \*(L":raw\*(R" and \&\*(L":crlf\*(R" are currently supported on DOS-derivative platforms. See \*(L"binmode\*(R" in perlfunc and open. .ie n .SS """\-T"" filetest recognizes \s-1UTF\-8\s0 encoded files as ""text""" .el .SS "\f(CW\-T\fP filetest recognizes \s-1UTF\-8\s0 encoded files as ``text''" .IX Subsection "-T filetest recognizes UTF-8 encoded files as text" The algorithm used for the \f(CW\*(C`\-T\*(C'\fR filetest has been enhanced to correctly identify \s-1UTF\-8\s0 content as \*(L"text\*(R". .SS "\fIsystem()\fP, backticks and pipe open now reflect \fIexec()\fP failure" .IX Subsection "system(), backticks and pipe open now reflect exec() failure" On Unix and similar platforms, \fIsystem()\fR, \fIqx()\fR and open(\s-1FOO\s0, \*(L"cmd |\*(R") etc., are implemented via \fIfork()\fR and \fIexec()\fR. When the underlying \&\fIexec()\fR fails, earlier versions did not report the error properly, since the \fIexec()\fR happened to be in a different process. .PP The child process now communicates with the parent about the error in launching the external command, which allows these constructs to return with their usual error value and set $!. .SS "Improved diagnostics" .IX Subsection "Improved diagnostics" Line numbers are no longer suppressed (under most likely circumstances) during the global destruction phase. .PP Diagnostics emitted from code running in threads other than the main thread are now accompanied by the thread \s-1ID\s0. .PP Embedded null characters in diagnostics now actually show up. They used to truncate the message in prior versions. .PP \&\f(CW$foo::a\fR and \f(CW$foo::b\fR are now exempt from \*(L"possible typo\*(R" warnings only if \fIsort()\fR is encountered in package \f(CW\*(C`foo\*(C'\fR. .PP Unrecognized alphabetic escapes encountered when parsing quote constructs now generate a warning, since they may take on new semantics in later versions of Perl. .PP Many diagnostics now report the internal operation in which the warning was provoked, like so: .PP .Vb 2 \& Use of uninitialized value in concatenation (.) at (eval 1) line 1. \& Use of uninitialized value in print at (eval 1) line 1. .Ve .PP Diagnostics that occur within eval may also report the file and line number where the eval is located, in addition to the eval sequence number and the line number within the evaluated text itself. For example: .PP .Vb 1 \& Not enough arguments for scalar at (eval 4)[newlib/perl5db.pl:1411] line 2, at EOF .Ve .SS "Diagnostics follow \s-1STDERR\s0" .IX Subsection "Diagnostics follow STDERR" Diagnostic output now goes to whichever file the \f(CW\*(C`STDERR\*(C'\fR handle is pointing at, instead of always going to the underlying C runtime library's \f(CW\*(C`stderr\*(C'\fR. .SS "More consistent close-on-exec behavior" .IX Subsection "More consistent close-on-exec behavior" On systems that support a close-on-exec flag on filehandles, the flag is now set for any handles created by \fIpipe()\fR, \fIsocketpair()\fR, \&\fIsocket()\fR, and \fIaccept()\fR, if that is warranted by the value of $^F that may be in effect. Earlier versions neglected to set the flag for handles created with these operators. See \*(L"pipe\*(R" in perlfunc, \&\*(L"socketpair\*(R" in perlfunc, \*(L"socket\*(R" in perlfunc, \*(L"accept\*(R" in perlfunc, and \*(L"$^F\*(R" in perlvar. .SS "\fIsyswrite()\fP ease-of-use" .IX Subsection "syswrite() ease-of-use" The length argument of \f(CW\*(C`syswrite()\*(C'\fR has become optional. .SS "Better syntax checks on parenthesized unary operators" .IX Subsection "Better syntax checks on parenthesized unary operators" Expressions such as: .PP .Vb 3 \& print defined(&foo,&bar,&baz); \& print uc("foo","bar","baz"); \& undef($foo,&bar); .Ve .PP used to be accidentally allowed in earlier versions, and produced unpredictable behaviour. Some produced ancillary warnings when used in this way; others silently did the wrong thing. .PP The parenthesized forms of most unary operators that expect a single argument now ensure that they are not called with more than one argument, making the cases shown above syntax errors. The usual behaviour of: .PP .Vb 3 \& print defined &foo, &bar, &baz; \& print uc "foo", "bar", "baz"; \& undef $foo, &bar; .Ve .PP remains unchanged. See perlop. .SS "Bit operators support full native integer width" .IX Subsection "Bit operators support full native integer width" The bit operators (& | ^ ~ << >>) now operate on the full native integral width (the exact size of which is available in \f(CW$Config\fR{ivsize}). For example, if your platform is either natively 64\-bit or if Perl has been configured to use 64\-bit integers, these operations apply to 8 bytes (as opposed to 4 bytes on 32\-bit platforms). For portability, be sure to mask off the excess bits in the result of unary \f(CW\*(C`~\*(C'\fR, e.g., \f(CW\*(C`~$x & 0xffffffff\*(C'\fR. .SS "Improved security features" .IX Subsection "Improved security features" More potentially unsafe operations taint their results for improved security. .PP The \f(CW\*(C`passwd\*(C'\fR and \f(CW\*(C`shell\*(C'\fR fields returned by the \fIgetpwent()\fR, \fIgetpwnam()\fR, and \fIgetpwuid()\fR are now tainted, because the user can affect their own encrypted password and login shell. .PP The variable modified by \fIshmread()\fR, and messages returned by \fImsgrcv()\fR (and its object-oriented interface IPC::SysV::Msg::rcv) are also tainted, because other untrusted processes can modify messages and shared memory segments for their own nefarious purposes. .SS "More functional bareword prototype (*)" .IX Subsection "More functional bareword prototype (*)" Bareword prototypes have been rationalized to enable them to be used to override builtins that accept barewords and interpret them in a special way, such as \f(CW\*(C`require\*(C'\fR or \f(CW\*(C`do\*(C'\fR. .PP Arguments prototyped as \f(CW\*(C`*\*(C'\fR will now be visible within the subroutine as either a simple scalar or as a reference to a typeglob. See \*(L"Prototypes\*(R" in perlsub. .ie n .SS """require"" and ""do"" may be overridden" .el .SS "\f(CWrequire\fP and \f(CWdo\fP may be overridden" .IX Subsection "require and do may be overridden" \&\f(CW\*(C`require\*(C'\fR and \f(CW\*(C`do \*(Aqfile\*(Aq\*(C'\fR operations may be overridden locally by importing subroutines of the same name into the current package (or globally by importing them into the \s-1CORE::GLOBAL::\s0 namespace). Overriding \f(CW\*(C`require\*(C'\fR will also affect \f(CW\*(C`use\*(C'\fR, provided the override is visible at compile-time. See \*(L"Overriding Built-in Functions\*(R" in perlsub. .SS "$^X variables may now have names longer than one character" .IX Subsection "$^X variables may now have names longer than one character" Formerly, $^X was synonymous with ${\*(L"\ecX\*(R"}, but $^XY was a syntax error. Now variable names that begin with a control character may be arbitrarily long. However, for compatibility reasons, these variables \&\fImust\fR be written with explicit braces, as \f(CW\*(C`${^XY}\*(C'\fR for example. \&\f(CW\*(C`${^XYZ}\*(C'\fR is synonymous with ${\*(L"\ecXYZ\*(R"}. Variable names with more than one control character, such as \f(CW\*(C`${^XY^Z}\*(C'\fR, are illegal. .PP The old syntax has not changed. As before, `^X' may be either a literal control-X character or the two-character sequence `caret' plus `X'. When braces are omitted, the variable name stops after the control character. Thus \f(CW"$^XYZ"\fR continues to be synonymous with \&\f(CW\*(C`$^X . "YZ"\*(C'\fR as before. .PP As before, lexical variables may not have names beginning with control characters. As before, variables whose names begin with a control character are always forced to be in package `main'. All such variables are reserved for future extensions, except those that begin with \&\f(CW\*(C`^_\*(C'\fR, which may be used by user programs and are guaranteed not to acquire special meaning in any future version of Perl. .ie n .SS "New variable $^C reflects ""\-c"" switch" .el .SS "New variable $^C reflects \f(CW\-c\fP switch" .IX Subsection "New variable $^C reflects -c switch" \&\f(CW$^C\fR has a boolean value that reflects whether perl is being run in compile-only mode (i.e. via the \f(CW\*(C`\-c\*(C'\fR switch). Since \&\s-1BEGIN\s0 blocks are executed under such conditions, this variable enables perl code to determine whether actions that make sense only during normal running are warranted. See perlvar. .SS "New variable $^V contains Perl version as a string" .IX Subsection "New variable $^V contains Perl version as a string" \&\f(CW$^V\fR contains the Perl version number as a string composed of characters whose ordinals match the version numbers, i.e. v5.6.0. This may be used in string comparisons. .PP See \f(CW\*(C`Support for strings represented as a vector of ordinals\*(C'\fR for an example. .SS "Optional Y2K warnings" .IX Subsection "Optional Y2K warnings" If Perl is built with the cpp macro \f(CW\*(C`PERL_Y2KWARN\*(C'\fR defined, it emits optional warnings when concatenating the number 19 with another number. .PP This behavior must be specifically enabled when running Configure. See \fI\s-1INSTALL\s0\fR and \fI\s-1README\s0.Y2K\fR. .SS "Arrays now always interpolate into double-quoted strings" .IX Subsection "Arrays now always interpolate into double-quoted strings" In double-quoted strings, arrays now interpolate, no matter what. The behavior in earlier versions of perl 5 was that arrays would interpolate into strings if the array had been mentioned before the string was compiled, and otherwise Perl would raise a fatal compile-time error. In versions 5.000 through 5.003, the error was .PP .Vb 1 \& Literal @example now requires backslash .Ve .PP In versions 5.004_01 through 5.6.0, the error was .PP .Vb 1 \& In string, @example now must be written as \e@example .Ve .PP The idea here was to get people into the habit of writing \&\f(CW"fred\e@example.com"\fR when they wanted a literal \f(CW\*(C`@\*(C'\fR sign, just as they have always written \f(CW"Give me back my \e$5"\fR when they wanted a literal \f(CW\*(C`$\*(C'\fR sign. .PP Starting with 5.6.1, when Perl now sees an \f(CW\*(C`@\*(C'\fR sign in a double-quoted string, it \fIalways\fR attempts to interpolate an array, regardless of whether or not the array has been used or declared already. The fatal error has been downgraded to an optional warning: .PP .Vb 1 \& Possible unintended interpolation of @example in string .Ve .PP This warns you that \f(CW"fred@example.com"\fR is going to turn into \&\f(CW\*(C`fred.com\*(C'\fR if you don't backslash the \f(CW\*(C`@\*(C'\fR. See http://perl.plover.com/at\-error.html for more details about the history here. .SS "@\- and @+ provide starting/ending offsets of regex submatches" .IX Subsection "@- and @+ provide starting/ending offsets of regex submatches" The new magic variables @\- and @+ provide the starting and ending offsets, respectively, of $&, \f(CW$1\fR, \f(CW$2\fR, etc. See perlvar for details. .SH "Modules and Pragmata" .IX Header "Modules and Pragmata" .SS "Modules" .IX Subsection "Modules" .IP "attributes" 4 .IX Item "attributes" While used internally by Perl as a pragma, this module also provides a way to fetch subroutine and variable attributes. See attributes. .IP "B" 4 .IX Item "B" The Perl Compiler suite has been extensively reworked for this release. More of the standard Perl test suite passes when run under the Compiler, but there is still a significant way to go to achieve production quality compiled executables. .Sp .Vb 3 \& NOTE: The Compiler suite remains highly experimental. The \& generated code may not be correct, even when it manages to execute \& without errors. .Ve .IP "Benchmark" 4 .IX Item "Benchmark" Overall, Benchmark results exhibit lower average error and better timing accuracy. .Sp You can now run tests for \fIn\fR seconds instead of guessing the right number of tests to run: e.g., timethese(\-5, ...) will run each code for at least 5 \s-1CPU\s0 seconds. Zero as the \*(L"number of repetitions\*(R" means \*(L"for at least 3 \s-1CPU\s0 seconds\*(R". The output format has also changed. For example: .Sp .Vb 1 \& use Benchmark;$x=3;timethese(\-5,{a=>sub{$x*$x},b=>sub{$x**2}}) .Ve .Sp will now output something like this: .Sp .Vb 3 \& Benchmark: running a, b, each for at least 5 CPU seconds... \& a: 5 wallclock secs ( 5.77 usr + 0.00 sys = 5.77 CPU) @ 200551.91/s (n=1156516) \& b: 4 wallclock secs ( 5.00 usr + 0.02 sys = 5.02 CPU) @ 159605.18/s (n=800686) .Ve .Sp New features: \*(L"each for at least N \s-1CPU\s0 seconds...\*(R", \*(L"wallclock secs\*(R", and the \*(L"@ operations/CPU second (n=operations)\*(R". .Sp \&\fItimethese()\fR now returns a reference to a hash of Benchmark objects containing the test results, keyed on the names of the tests. .Sp \&\fItimethis()\fR now returns the iterations field in the Benchmark result object instead of 0. .Sp \&\fItimethese()\fR, \fItimethis()\fR, and the new \fIcmpthese()\fR (see below) can also take a format specifier of 'none' to suppress output. .Sp A new function \fIcountit()\fR is just like \fItimeit()\fR except that it takes a \&\s-1TIME\s0 instead of a \s-1COUNT\s0. .Sp A new function \fIcmpthese()\fR prints a chart comparing the results of each test returned from a \fItimethese()\fR call. For each possible pair of tests, the percentage speed difference (iters/sec or seconds/iter) is shown. .Sp For other details, see Benchmark. .IP "ByteLoader" 4 .IX Item "ByteLoader" The ByteLoader is a dedicated extension to generate and run Perl bytecode. See ByteLoader. .IP "constant" 4 .IX Item "constant" References can now be used. .Sp The new version also allows a leading underscore in constant names, but disallows a double leading underscore (as in \*(L"_\|_LINE_\|_\*(R"). Some other names are disallowed or warned against, including \s-1BEGIN\s0, \s-1END\s0, etc. Some names which were forced into main:: used to fail silently in some cases; now they're fatal (outside of main::) and an optional warning (inside of main::). The ability to detect whether a constant had been set with a given name has been added. .Sp See constant. .IP "charnames" 4 .IX Item "charnames" This pragma implements the \f(CW\*(C`\eN\*(C'\fR string escape. See charnames. .IP "Data::Dumper" 4 .IX Item "Data::Dumper" A \f(CW\*(C`Maxdepth\*(C'\fR setting can be specified to avoid venturing too deeply into deep data structures. See Data::Dumper. .Sp The \s-1XSUB\s0 implementation of \fIDump()\fR is now automatically called if the \&\f(CW\*(C`Useqq\*(C'\fR setting is not in use. .Sp Dumping \f(CW\*(C`qr//\*(C'\fR objects works correctly. .IP "\s-1DB\s0" 4 .IX Item "DB" \&\f(CW\*(C`DB\*(C'\fR is an experimental module that exposes a clean abstraction to Perl's debugging \s-1API\s0. .IP "DB_File" 4 .IX Item "DB_File" DB_File can now be built with Berkeley \s-1DB\s0 versions 1, 2 or 3. See \f(CW\*(C`ext/DB_File/Changes\*(C'\fR. .IP "Devel::DProf" 4 .IX Item "Devel::DProf" Devel::DProf, a Perl source code profiler has been added. See Devel::DProf and dprofpp. .IP "Devel::Peek" 4 .IX Item "Devel::Peek" The Devel::Peek module provides access to the internal representation of Perl variables and data. It is a data debugging tool for the \s-1XS\s0 programmer. .IP "Dumpvalue" 4 .IX Item "Dumpvalue" The Dumpvalue module provides screen dumps of Perl data. .IP "DynaLoader" 4 .IX Item "DynaLoader" DynaLoader now supports a \fIdl_unload_file()\fR function on platforms that support unloading shared objects using \fIdlclose()\fR. .Sp Perl can also optionally arrange to unload all extension shared objects loaded by Perl. To enable this, build Perl with the Configure option \&\f(CW\*(C`\-Accflags=\-DDL_UNLOAD_ALL_AT_EXIT\*(C'\fR. (This maybe useful if you are using Apache with mod_perl.) .IP "English" 4 .IX Item "English" \&\f(CW$PERL_VERSION\fR now stands for \f(CW$^V\fR (a string value) rather than for \f(CW$]\fR (a numeric value). .IP "Env" 4 .IX Item "Env" Env now supports accessing environment variables like \s-1PATH\s0 as array variables. .IP "Fcntl" 4 .IX Item "Fcntl" More Fcntl constants added: F_SETLK64, F_SETLKW64, O_LARGEFILE for large file (more than 4GB) access (\s-1NOTE:\s0 the O_LARGEFILE is automatically added to \fIsysopen()\fR flags if large file support has been configured, as is the default), Free/Net/OpenBSD locking behaviour flags F_FLOCK, F_POSIX, Linux F_SHLCK, and O_ACCMODE: the combined mask of O_RDONLY, O_WRONLY, and O_RDWR. The \fIseek()\fR/\fIsysseek()\fR constants \s-1SEEK_SET\s0, \s-1SEEK_CUR\s0, and \s-1SEEK_END\s0 are available via the \&\f(CW\*(C`:seek\*(C'\fR tag. The \fIchmod()\fR/\fIstat()\fR S_IF* constants and S_IS* functions are available via the \f(CW\*(C`:mode\*(C'\fR tag. .IP "File::Compare" 4 .IX Item "File::Compare" A \fIcompare_text()\fR function has been added, which allows custom comparison functions. See File::Compare. .IP "File::Find" 4 .IX Item "File::Find" File::Find now works correctly when the \fIwanted()\fR function is either autoloaded or is a symbolic reference. .Sp A bug that caused File::Find to lose track of the working directory when pruning top-level directories has been fixed. .Sp File::Find now also supports several other options to control its behavior. It can follow symbolic links if the \f(CW\*(C`follow\*(C'\fR option is specified. Enabling the \f(CW\*(C`no_chdir\*(C'\fR option will make File::Find skip changing the current directory when walking directories. The \f(CW\*(C`untaint\*(C'\fR flag can be useful when running with taint checks enabled. .Sp See File::Find. .IP "File::Glob" 4 .IX Item "File::Glob" This extension implements BSD-style file globbing. By default, it will also be used for the internal implementation of the \fIglob()\fR operator. See File::Glob. .IP "File::Spec" 4 .IX Item "File::Spec" New methods have been added to the File::Spec module: \fIdevnull()\fR returns the name of the null device (/dev/null on Unix) and \fItmpdir()\fR the name of the temp directory (normally /tmp on Unix). There are now also methods to convert between absolute and relative filenames: \fIabs2rel()\fR and \&\fIrel2abs()\fR. For compatibility with operating systems that specify volume names in file paths, the \fIsplitpath()\fR, \fIsplitdir()\fR, and \fIcatdir()\fR methods have been added. .IP "File::Spec::Functions" 4 .IX Item "File::Spec::Functions" The new File::Spec::Functions modules provides a function interface to the File::Spec module. Allows shorthand .Sp .Vb 1 \& $fullname = catfile($dir1, $dir2, $file); .Ve .Sp instead of .Sp .Vb 1 \& $fullname = File::Spec\->catfile($dir1, $dir2, $file); .Ve .IP "Getopt::Long" 4 .IX Item "Getopt::Long" Getopt::Long licensing has changed to allow the Perl Artistic License as well as the \s-1GPL\s0. It used to be \s-1GPL\s0 only, which got in the way of non-GPL applications that wanted to use Getopt::Long. .Sp Getopt::Long encourages the use of Pod::Usage to produce help messages. For example: .Sp .Vb 7 \& use Getopt::Long; \& use Pod::Usage; \& my $man = 0; \& my $help = 0; \& GetOptions(\*(Aqhelp|?\*(Aq => \e$help, man => \e$man) or pod2usage(2); \& pod2usage(1) if $help; \& pod2usage(\-exitstatus => 0, \-verbose => 2) if $man; \& \& _\|_END_\|_ \& \& =head1 NAME \& \& sample \- Using Getopt::Long and Pod::Usage \& \& =head1 SYNOPSIS \& \& sample [options] [file ...] \& \& Options: \& \-help brief help message \& \-man full documentation \& \& =head1 OPTIONS \& \& =over 8 \& \& =item B<\-help> \& \& Print a brief help message and exits. \& \& =item B<\-man> \& \& Prints the manual page and exits. \& \& =back \& \& =head1 DESCRIPTION \& \& B<This program> will read the given input file(s) and do something \& useful with the contents thereof. \& \& =cut .Ve .Sp See Pod::Usage for details. .Sp A bug that prevented the non-option call-back <> from being specified as the first argument has been fixed. .Sp To specify the characters < and > as option starters, use ><. Note, however, that changing option starters is strongly deprecated. .IP "\s-1IO\s0" 4 .IX Item "IO" \&\fIwrite()\fR and \fIsyswrite()\fR will now accept a single-argument form of the call, for consistency with Perl's \fIsyswrite()\fR. .Sp You can now create a TCP-based IO::Socket::INET without forcing a connect attempt. This allows you to configure its options (like making it non-blocking) and then call \fIconnect()\fR manually. .Sp A bug that prevented the \fIIO::Socket::protocol()\fR accessor from ever returning the correct value has been corrected. .Sp IO::Socket::connect now uses non-blocking \s-1IO\s0 instead of \fIalarm()\fR to do connect timeouts. .Sp IO::Socket::accept now uses \fIselect()\fR instead of \fIalarm()\fR for doing timeouts. .Sp IO::Socket::INET\->new now sets $! correctly on failure. $@ is still set for backwards compatibility. .IP "\s-1JPL\s0" 4 .IX Item "JPL" Java Perl Lingo is now distributed with Perl. See jpl/README for more information. .IP "lib" 4 .IX Item "lib" \&\f(CW\*(C`use lib\*(C'\fR now weeds out any trailing duplicate entries. \&\f(CW\*(C`no lib\*(C'\fR removes all named entries. .IP "Math::BigInt" 4 .IX Item "Math::BigInt" The bitwise operations \f(CW\*(C`<<\*(C'\fR, \f(CW\*(C`>>\*(C'\fR, \f(CW\*(C`&\*(C'\fR, \f(CW\*(C`|\*(C'\fR, and \f(CW\*(C`~\*(C'\fR are now supported on bigints. .IP "Math::Complex" 4 .IX Item "Math::Complex" The accessor methods Re, Im, arg, abs, rho, and theta can now also act as mutators (accessor \f(CW$z\fR\->\fIRe()\fR, mutator \f(CW$z\fR\->\fIRe\fR\|(3)). .Sp The class method \f(CW\*(C`display_format\*(C'\fR and the corresponding object method \&\f(CW\*(C`display_format\*(C'\fR, in addition to accepting just one argument, now can also accept a parameter hash. Recognized keys of a parameter hash are \&\f(CW"style"\fR, which corresponds to the old one parameter case, and two new parameters: \f(CW"format"\fR, which is a \fIprintf()\fR\-style format string (defaults usually to \f(CW"%.15g"\fR, you can revert to the default by setting the format string to \f(CW\*(C`undef\*(C'\fR) used for both parts of a complex number, and \f(CW"polar_pretty_print"\fR (defaults to true), which controls whether an attempt is made to try to recognize small multiples and rationals of pi (2pi, pi/2) at the argument (angle) of a polar complex number. .Sp The potentially disruptive change is that in list context both methods now \fIreturn the parameter hash\fR, instead of only the value of the \&\f(CW"style"\fR parameter. .IP "Math::Trig" 4 .IX Item "Math::Trig" A little bit of radial trigonometry (cylindrical and spherical), radial coordinate conversions, and the great circle distance were added. .IP "Pod::Parser, Pod::InputObjects" 4 .IX Item "Pod::Parser, Pod::InputObjects" Pod::Parser is a base class for parsing and selecting sections of pod documentation from an input stream. This module takes care of identifying pod paragraphs and commands in the input and hands off the parsed paragraphs and commands to user-defined methods which are free to interpret or translate them as they see fit. .Sp Pod::InputObjects defines some input objects needed by Pod::Parser, and for advanced users of Pod::Parser that need more about a command besides its name and text. .Sp As of release 5.6.0 of Perl, Pod::Parser is now the officially sanctioned \&\*(L"base parser code\*(R" recommended for use by all pod2xxx translators. Pod::Text (pod2text) and Pod::Man (pod2man) have already been converted to use Pod::Parser and efforts to convert Pod::HTML (pod2html) are already underway. For any questions or comments about pod parsing and translating issues and utilities, please use the pod\-people@perl.org mailing list. .Sp For further information, please see Pod::Parser and Pod::InputObjects. .IP "Pod::Checker, podchecker" 4 .IX Item "Pod::Checker, podchecker" This utility checks pod files for correct syntax, according to perlpod. Obvious errors are flagged as such, while warnings are printed for mistakes that can be handled gracefully. The checklist is not complete yet. See Pod::Checker. .IP "Pod::ParseUtils, Pod::Find" 4 .IX Item "Pod::ParseUtils, Pod::Find" These modules provide a set of gizmos that are useful mainly for pod translators. Pod::Find traverses directory structures and returns found pod files, along with their canonical names (like \&\f(CW\*(C`File::Spec::Unix\*(C'\fR). Pod::ParseUtils contains \&\fBPod::List\fR (useful for storing pod list information), \fBPod::Hyperlink\fR (for parsing the contents of \f(CW\*(C`L<>\*(C'\fR sequences) and \fBPod::Cache\fR (for caching information about pod files, e.g., link nodes). .IP "Pod::Select, podselect" 4 .IX Item "Pod::Select, podselect" Pod::Select is a subclass of Pod::Parser which provides a function named \*(L"\fIpodselect()\fR\*(R" to filter out user-specified sections of raw pod documentation from an input stream. podselect is a script that provides access to Pod::Select from other scripts to be used as a filter. See Pod::Select. .IP "Pod::Usage, pod2usage" 4 .IX Item "Pod::Usage, pod2usage" Pod::Usage provides the function \*(L"\fIpod2usage()\fR\*(R" to print usage messages for a Perl script based on its embedded pod documentation. The \fIpod2usage()\fR function is generally useful to all script authors since it lets them write and maintain a single source (the pods) for documentation, thus removing the need to create and maintain redundant usage message text consisting of information already in the pods. .Sp There is also a pod2usage script which can be used from other kinds of scripts to print usage messages from pods (even for non-Perl scripts with pods embedded in comments). .Sp For details and examples, please see Pod::Usage. .IP "Pod::Text and Pod::Man" 4 .IX Item "Pod::Text and Pod::Man" Pod::Text has been rewritten to use Pod::Parser. While \fIpod2text()\fR is still available for backwards compatibility, the module now has a new preferred interface. See Pod::Text for the details. The new Pod::Text module is easily subclassed for tweaks to the output, and two such subclasses (Pod::Text::Termcap for man-page-style bold and underlining using termcap information, and Pod::Text::Color for markup with \s-1ANSI\s0 color sequences) are now standard. .Sp pod2man has been turned into a module, Pod::Man, which also uses Pod::Parser. In the process, several outstanding bugs related to quotes in section headers, quoting of code escapes, and nested lists have been fixed. pod2man is now a wrapper script around this module. .IP "SDBM_File" 4 .IX Item "SDBM_File" An \s-1EXISTS\s0 method has been added to this module (and \fIsdbm_exists()\fR has been added to the underlying sdbm library), so one can now call exists on an SDBM_File tied hash and get the correct result, rather than a runtime error. .Sp A bug that may have caused data loss when more than one disk block happens to be read from the database in a single \s-1\fIFETCH\s0()\fR has been fixed. .IP "Sys::Syslog" 4 .IX Item "Sys::Syslog" Sys::Syslog now uses XSUBs to access facilities from syslog.h so it no longer requires syslog.ph to exist. .IP "Sys::Hostname" 4 .IX Item "Sys::Hostname" Sys::Hostname now uses XSUBs to call the C library's \fIgethostname()\fR or \&\fIuname()\fR if they exist. .IP "Term::ANSIColor" 4 .IX Item "Term::ANSIColor" Term::ANSIColor is a very simple module to provide easy and readable access to the \s-1ANSI\s0 color and highlighting escape sequences, supported by most \s-1ANSI\s0 terminal emulators. It is now included standard. .IP "Time::Local" 4 .IX Item "Time::Local" The \fItimelocal()\fR and \fItimegm()\fR functions used to silently return bogus results when the date fell outside the machine's integer range. They now consistently \fIcroak()\fR if the date falls in an unsupported range. .IP "Win32" 4 .IX Item "Win32" The error return value in list context has been changed for all functions that return a list of values. Previously these functions returned a list with a single element \f(CW\*(C`undef\*(C'\fR if an error occurred. Now these functions return the empty list in these situations. This applies to the following functions: .Sp .Vb 2 \& Win32::FsType \& Win32::GetOSVersion .Ve .Sp The remaining functions are unchanged and continue to return \f(CW\*(C`undef\*(C'\fR on error even in list context. .Sp The Win32::SetLastError(\s-1ERROR\s0) function has been added as a complement to the \fIWin32::GetLastError()\fR function. .Sp The new Win32::GetFullPathName(\s-1FILENAME\s0) returns the full absolute pathname for \s-1FILENAME\s0 in scalar context. In list context it returns a two-element list containing the fully qualified directory name and the filename. See Win32. .IP "XSLoader" 4 .IX Item "XSLoader" The XSLoader extension is a simpler alternative to DynaLoader. See XSLoader. .IP "\s-1DBM\s0 Filters" 4 .IX Item "DBM Filters" A new feature called \*(L"\s-1DBM\s0 Filters\*(R" has been added to all the \&\s-1DBM\s0 modules\-\-DB_File, GDBM_File, NDBM_File, ODBM_File, and SDBM_File. \&\s-1DBM\s0 Filters add four new methods to each \s-1DBM\s0 module: .Sp .Vb 4 \& filter_store_key \& filter_store_value \& filter_fetch_key \& filter_fetch_value .Ve .Sp These can be used to filter key-value pairs before the pairs are written to the database or just after they are read from the database. See perldbmfilter for further information. .SS "Pragmata" .IX Subsection "Pragmata" \&\f(CW\*(C`use attrs\*(C'\fR is now obsolete, and is only provided for backward-compatibility. It's been replaced by the \f(CW\*(C`sub : attributes\*(C'\fR syntax. See \*(L"Subroutine Attributes\*(R" in perlsub and attributes. .PP Lexical warnings pragma, \f(CW\*(C`use warnings;\*(C'\fR, to control optional warnings. See perllexwarn. .PP \&\f(CW\*(C`use filetest\*(C'\fR to control the behaviour of filetests (\f(CW\*(C`\-r\*(C'\fR \f(CW\*(C`\-w\*(C'\fR \&...). Currently only one subpragma implemented, \*(L"use filetest \&'access';\*(R", that uses \fIaccess\fR\|(2) or equivalent to check permissions instead of using \fIstat\fR\|(2) as usual. This matters in filesystems where there are ACLs (access control lists): the \fIstat\fR\|(2) might lie, but \fIaccess\fR\|(2) knows better. .PP The \f(CW\*(C`open\*(C'\fR pragma can be used to specify default disciplines for handle constructors (e.g. \fIopen()\fR) and for qx//. The two pseudo-disciplines \f(CW\*(C`:raw\*(C'\fR and \f(CW\*(C`:crlf\*(C'\fR are currently supported on DOS-derivative platforms (i.e. where binmode is not a no-op). See also \*(L"\fIbinmode()\fR can be used to set :crlf and :raw modes\*(R". .SH "Utility Changes" .IX Header "Utility Changes" .SS "dprofpp" .IX Subsection "dprofpp" \&\f(CW\*(C`dprofpp\*(C'\fR is used to display profile data generated using \f(CW\*(C`Devel::DProf\*(C'\fR. See dprofpp. .SS "find2perl" .IX Subsection "find2perl" The \f(CW\*(C`find2perl\*(C'\fR utility now uses the enhanced features of the File::Find module. The \-depth and \-follow options are supported. Pod documentation is also included in the script. .SS "h2xs" .IX Subsection "h2xs" The \f(CW\*(C`h2xs\*(C'\fR tool can now work in conjunction with \f(CW\*(C`C::Scan\*(C'\fR (available from \s-1CPAN\s0) to automatically parse real-life header files. The \f(CW\*(C`\-M\*(C'\fR, \&\f(CW\*(C`\-a\*(C'\fR, \f(CW\*(C`\-k\*(C'\fR, and \f(CW\*(C`\-o\*(C'\fR options are new. .SS "perlcc" .IX Subsection "perlcc" \&\f(CW\*(C`perlcc\*(C'\fR now supports the C and Bytecode backends. By default, it generates output from the simple C backend rather than the optimized C backend. .PP Support for non-Unix platforms has been improved. .SS "perldoc" .IX Subsection "perldoc" \&\f(CW\*(C`perldoc\*(C'\fR has been reworked to avoid possible security holes. It will not by default let itself be run as the superuser, but you may still use the \fB\-U\fR switch to try to make it drop privileges first. .SS "The Perl Debugger" .IX Subsection "The Perl Debugger" Many bug fixes and enhancements were added to \fIperl5db.pl\fR, the Perl debugger. The help documentation was rearranged. New commands include \f(CW\*(C`< ?\*(C'\fR, \f(CW\*(C`> ?\*(C'\fR, and \f(CW\*(C`{ ?\*(C'\fR to list out current actions, \f(CW\*(C`man \f(CIdocpage\f(CW\*(C'\fR to run your doc viewer on some perl docset, and support for quoted options. The help information was rearranged, and should be viewable once again if you're using \fBless\fR as your pager. A serious security hole was plugged\*(--you should immediately remove all older versions of the Perl debugger as installed in previous releases, all the way back to perl3, from your system to avoid being bitten by this. .SH "Improved Documentation" .IX Header "Improved Documentation" Many of the platform-specific \s-1README\s0 files are now part of the perl installation. See perl for the complete list. .IP "perlapi.pod" 4 .IX Item "perlapi.pod" The official list of public Perl \s-1API\s0 functions. .IP "perlboot.pod" 4 .IX Item "perlboot.pod" A tutorial for beginners on object-oriented Perl. .IP "perlcompile.pod" 4 .IX Item "perlcompile.pod" An introduction to using the Perl Compiler suite. .IP "perldbmfilter.pod" 4 .IX Item "perldbmfilter.pod" A howto document on using the \s-1DBM\s0 filter facility. .IP "perldebug.pod" 4 .IX Item "perldebug.pod" All material unrelated to running the Perl debugger, plus all low-level guts-like details that risked crushing the casual user of the debugger, have been relocated from the old manpage to the next entry below. .IP "perldebguts.pod" 4 .IX Item "perldebguts.pod" This new manpage contains excessively low-level material not related to the Perl debugger, but slightly related to debugging Perl itself. It also contains some arcane internal details of how the debugging process works that may only be of interest to developers of Perl debuggers. .IP "perlfork.pod" 4 .IX Item "perlfork.pod" Notes on the \fIfork()\fR emulation currently available for the Windows platform. .IP "perlfilter.pod" 4 .IX Item "perlfilter.pod" An introduction to writing Perl source filters. .IP "perlhack.pod" 4 .IX Item "perlhack.pod" Some guidelines for hacking the Perl source code. .IP "perlintern.pod" 4 .IX Item "perlintern.pod" A list of internal functions in the Perl source code. (List is currently empty.) .IP "perllexwarn.pod" 4 .IX Item "perllexwarn.pod" Introduction and reference information about lexically scoped warning categories. .IP "perlnumber.pod" 4 .IX Item "perlnumber.pod" Detailed information about numbers as they are represented in Perl. .IP "perlopentut.pod" 4 .IX Item "perlopentut.pod" A tutorial on using \fIopen()\fR effectively. .IP "perlreftut.pod" 4 .IX Item "perlreftut.pod" A tutorial that introduces the essentials of references. .IP "perltootc.pod" 4 .IX Item "perltootc.pod" A tutorial on managing class data for object modules. .IP "perltodo.pod" 4 .IX Item "perltodo.pod" Discussion of the most often wanted features that may someday be supported in Perl. .IP "perlunicode.pod" 4 .IX Item "perlunicode.pod" An introduction to Unicode support features in Perl. .SH "Performance enhancements" .IX Header "Performance enhancements" .ie n .SS "Simple \fIsort()\fP using { $a <=> $b } and the like are optimized" .el .SS "Simple \fIsort()\fP using { \f(CW$a\fP <=> \f(CW$b\fP } and the like are optimized" .IX Subsection "Simple sort() using { $a <=> $b } and the like are optimized" Many common \fIsort()\fR operations using a simple inlined block are now optimized for faster performance. .SS "Optimized assignments to lexical variables" .IX Subsection "Optimized assignments to lexical variables" Certain operations in the \s-1RHS\s0 of assignment statements have been optimized to directly set the lexical variable on the \s-1LHS\s0, eliminating redundant copying overheads. .SS "Faster subroutine calls" .IX Subsection "Faster subroutine calls" Minor changes in how subroutine calls are handled internally provide marginal improvements in performance. .SS "\fIdelete()\fP, \fIeach()\fP, \fIvalues()\fP and hash iteration are faster" .IX Subsection "delete(), each(), values() and hash iteration are faster" The hash values returned by \fIdelete()\fR, \fIeach()\fR, \fIvalues()\fR and hashes in a list context are the actual values in the hash, instead of copies. This results in significantly better performance, because it eliminates needless copying in most situations. .SH "Installation and Configuration Improvements" .IX Header "Installation and Configuration Improvements" .SS "\-Dusethreads means something different" .IX Subsection "-Dusethreads means something different" The \-Dusethreads flag now enables the experimental interpreter-based thread support by default. To get the flavor of experimental threads that was in 5.005 instead, you need to run Configure with \*(L"\-Dusethreads \-Duse5005threads\*(R". .PP As of v5.6.0, interpreter-threads support is still lacking a way to create new threads from Perl (i.e., \f(CW\*(C`use Thread;\*(C'\fR will not work with interpreter threads). \f(CW\*(C`use Thread;\*(C'\fR continues to be available when you specify the \-Duse5005threads option to Configure, bugs and all. .PP .Vb 2 \& NOTE: Support for threads continues to be an experimental feature. \& Interfaces and implementation are subject to sudden and drastic changes. .Ve .SS "New Configure flags" .IX Subsection "New Configure flags" The following new flags may be enabled on the Configure command line by running Configure with \f(CW\*(C`\-Dflag\*(C'\fR. .PP .Vb 3 \& usemultiplicity \& usethreads useithreads (new interpreter threads: no Perl API yet) \& usethreads use5005threads (threads as they were in 5.005) \& \& use64bitint (equal to now deprecated \*(Aquse64bits\*(Aq) \& use64bitall \& \& uselongdouble \& usemorebits \& uselargefiles \& usesocks (only SOCKS v5 supported) .Ve .SS "Threadedness and 64\-bitness now more daring" .IX Subsection "Threadedness and 64-bitness now more daring" The Configure options enabling the use of threads and the use of 64\-bitness are now more daring in the sense that they no more have an explicit list of operating systems of known threads/64\-bit capabilities. In other words: if your operating system has the necessary APIs and datatypes, you should be able just to go ahead and use them, for threads by Configure \-Dusethreads, and for 64 bits either explicitly by Configure \-Duse64bitint or implicitly if your system has 64\-bit wide datatypes. See also \*(L"64\-bit support\*(R". .SS "Long Doubles" .IX Subsection "Long Doubles" Some platforms have \*(L"long doubles\*(R", floating point numbers of even larger range than ordinary \*(L"doubles\*(R". To enable using long doubles for Perl's scalars, use \-Duselongdouble. .SS "\-Dusemorebits" .IX Subsection "-Dusemorebits" You can enable both \-Duse64bitint and \-Duselongdouble with \-Dusemorebits. See also \*(L"64\-bit support\*(R". .SS "\-Duselargefiles" .IX Subsection "-Duselargefiles" Some platforms support system APIs that are capable of handling large files (typically, files larger than two gigabytes). Perl will try to use these APIs if you ask for \-Duselargefiles. .PP See \*(L"Large file support\*(R" for more information. .SS "installusrbinperl" .IX Subsection "installusrbinperl" You can use \*(L"Configure \-Uinstallusrbinperl\*(R" which causes installperl to skip installing perl also as /usr/bin/perl. This is useful if you prefer not to modify /usr/bin for some reason or another but harmful because many scripts assume to find Perl in /usr/bin/perl. .SS "\s-1SOCKS\s0 support" .IX Subsection "SOCKS support" You can use \*(L"Configure \-Dusesocks\*(R" which causes Perl to probe for the \s-1SOCKS\s0 proxy protocol library (v5, not v4). For more information on \s-1SOCKS\s0, see: .PP .Vb 1 \& http://www.socks.nec.com/ .Ve .ie n .SS """\-A"" flag" .el .SS "\f(CW\-A\fP flag" .IX Subsection "-A flag" You can \*(L"post-edit\*(R" the Configure variables using the Configure \f(CW\*(C`\-A\*(C'\fR switch. The editing happens immediately after the platform specific hints files have been processed but before the actual configuration process starts. Run \f(CW\*(C`Configure \-h\*(C'\fR to find out the full \f(CW\*(C`\-A\*(C'\fR syntax. .SS "Enhanced Installation Directories" .IX Subsection "Enhanced Installation Directories" The installation structure has been enriched to improve the support for maintaining multiple versions of perl, to provide locations for vendor-supplied modules, scripts, and manpages, and to ease maintenance of locally-added modules, scripts, and manpages. See the section on Installation Directories in the \s-1INSTALL\s0 file for complete details. For most users building and installing from source, the defaults should be fine. .PP If you previously used \f(CW\*(C`Configure \-Dsitelib\*(C'\fR or \f(CW\*(C`\-Dsitearch\*(C'\fR to set special values for library directories, you might wish to consider using the new \f(CW\*(C`\-Dsiteprefix\*(C'\fR setting instead. Also, if you wish to re-use a config.sh file from an earlier version of perl, you should be sure to check that Configure makes sensible choices for the new directories. See \s-1INSTALL\s0 for complete details. .SS "gcc automatically tried if 'cc' does not seem to be working" .IX Subsection "gcc automatically tried if 'cc' does not seem to be working" In many platforms the vendor-supplied 'cc' is too stripped-down to build Perl (basically, the 'cc' doesn't do \s-1ANSI\s0 C). If this seems to be the case and the 'cc' does not seem to be the \s-1GNU\s0 C compiler \&'gcc', an automatic attempt is made to find and use 'gcc' instead. .SH "Platform specific changes" .IX Header "Platform specific changes" .SS "Supported platforms" .IX Subsection "Supported platforms" .IP "\(bu" 4 The Mach CThreads (\s-1NEXTSTEP\s0, \s-1OPENSTEP\s0) are now supported by the Thread extension. .IP "\(bu" 4 GNU/Hurd is now supported. .IP "\(bu" 4 Rhapsody/Darwin is now supported. .IP "\(bu" 4 \&\s-1EPOC\s0 is now supported (on Psion 5). .IP "\(bu" 4 The cygwin port (formerly cygwin32) has been greatly improved. .SS "\s-1DOS\s0" .IX Subsection "DOS" .IP "\(bu" 4 Perl now works with djgpp 2.02 (and 2.03 alpha). .IP "\(bu" 4 Environment variable names are not converted to uppercase any more. .IP "\(bu" 4 Incorrect exit codes from backticks have been fixed. .IP "\(bu" 4 This port continues to use its own builtin globbing (not File::Glob). .SS "\s-1OS390\s0 (OpenEdition \s-1MVS\s0)" .IX Subsection "OS390 (OpenEdition MVS)" Support for this \s-1EBCDIC\s0 platform has not been renewed in this release. There are difficulties in reconciling Perl's standardization on \s-1UTF\-8\s0 as its internal representation for characters with the \s-1EBCDIC\s0 character set, because the two are incompatible. .PP It is unclear whether future versions will renew support for this platform, but the possibility exists. .SS "\s-1VMS\s0" .IX Subsection "VMS" Numerous revisions and extensions to configuration, build, testing, and installation process to accommodate core changes and VMS-specific options. .PP Expand \f(CW%ENV\fR\-handling code to allow runtime mapping to logical names, \&\s-1CLI\s0 symbols, and \s-1CRTL\s0 environ array. .PP Extension of subprocess invocation code to accept filespecs as command \&\*(L"verbs\*(R". .PP Add to Perl command line processing the ability to use default file types and to recognize Unix-style \f(CW\*(C`2>&1\*(C'\fR. .PP Expansion of File::Spec::VMS routines, and integration into ExtUtils::MM_VMS. .PP Extension of ExtUtils::MM_VMS to handle complex extensions more flexibly. .PP Barewords at start of Unix-syntax paths may be treated as text rather than only as logical names. .PP Optional secure translation of several logical names used internally by Perl. .PP Miscellaneous bugfixing and porting of new core code to \s-1VMS\s0. .PP Thanks are gladly extended to the many people who have contributed \s-1VMS\s0 patches, testing, and ideas. .SS "Win32" .IX Subsection "Win32" Perl can now emulate \fIfork()\fR internally, using multiple interpreters running in different concurrent threads. This support must be enabled at build time. See perlfork for detailed information. .PP When given a pathname that consists only of a drivename, such as \f(CW\*(C`A:\*(C'\fR, \&\fIopendir()\fR and \fIstat()\fR now use the current working directory for the drive rather than the drive root. .PP The builtin \s-1XSUB\s0 functions in the Win32:: namespace are documented. See Win32. .PP $^X now contains the full path name of the running executable. .PP A \fIWin32::GetLongPathName()\fR function is provided to complement \&\fIWin32::GetFullPathName()\fR and \fIWin32::GetShortPathName()\fR. See Win32. .PP \&\fIPOSIX::uname()\fR is supported. .PP system(1,...) now returns true process IDs rather than process handles. \fIkill()\fR accepts any real process id, rather than strictly return values from system(1,...). .PP For better compatibility with Unix, \f(CW\*(C`kill(0, $pid)\*(C'\fR can now be used to test whether a process exists. .PP The \f(CW\*(C`Shell\*(C'\fR module is supported. .PP Better support for building Perl under command.com in Windows 95 has been added. .PP Scripts are read in binary mode by default to allow ByteLoader (and the filter mechanism in general) to work properly. For compatibility, the \s-1DATA\s0 filehandle will be set to text mode if a carriage return is detected at the end of the line containing the _\|_END_\|_ or _\|_DATA_\|_ token; if not, the \s-1DATA\s0 filehandle will be left open in binary mode. Earlier versions always opened the \s-1DATA\s0 filehandle in text mode. .PP The \fIglob()\fR operator is implemented via the \f(CW\*(C`File::Glob\*(C'\fR extension, which supports glob syntax of the C shell. This increases the flexibility of the \fIglob()\fR operator, but there may be compatibility issues for programs that relied on the older globbing syntax. If you want to preserve compatibility with the older syntax, you might want to run perl with \f(CW\*(C`\-MFile::DosGlob\*(C'\fR. For details and compatibility information, see File::Glob. .SH "Significant bug fixes" .IX Header "Significant bug fixes" .SS "<\s-1HANDLE\s0> on empty files" .IX Subsection "<HANDLE> on empty files" With \f(CW$/\fR set to \f(CW\*(C`undef\*(C'\fR, \*(L"slurping\*(R" an empty file returns a string of zero length (instead of \f(CW\*(C`undef\*(C'\fR, as it used to) the first time the \&\s-1HANDLE\s0 is read after \f(CW$/\fR is set to \f(CW\*(C`undef\*(C'\fR. Further reads yield \&\f(CW\*(C`undef\*(C'\fR. .PP This means that the following will append \*(L"foo\*(R" to an empty file (it used to do nothing): .PP .Vb 1 \& perl \-0777 \-pi \-e \*(Aqs/^/foo/\*(Aq empty_file .Ve .PP The behaviour of: .PP .Vb 1 \& perl \-pi \-e \*(Aqs/^/foo/\*(Aq empty_file .Ve .PP is unchanged (it continues to leave the file empty). .ie n .SS """eval \*(Aq...\*(Aq"" improvements" .el .SS "\f(CWeval \*(Aq...\*(Aq\fP improvements" .IX Subsection "eval ... improvements" Line numbers (as reflected by \fIcaller()\fR and most diagnostics) within \&\f(CW\*(C`eval \*(Aq...\*(Aq\*(C'\fR were often incorrect where here documents were involved. This has been corrected. .PP Lexical lookups for variables appearing in \f(CW\*(C`eval \*(Aq...\*(Aq\*(C'\fR within functions that were themselves called within an \f(CW\*(C`eval \*(Aq...\*(Aq\*(C'\fR were searching the wrong place for lexicals. The lexical search now correctly ends at the subroutine's block boundary. .PP The use of \f(CW\*(C`return\*(C'\fR within \f(CW\*(C`eval {...}\*(C'\fR caused $@ not to be reset correctly when no exception occurred within the eval. This has been fixed. .PP Parsing of here documents used to be flawed when they appeared as the replacement expression in \f(CW\*(C`eval \*(Aqs/.../.../e\*(Aq\*(C'\fR. This has been fixed. .SS "All compilation errors are true errors" .IX Subsection "All compilation errors are true errors" Some \*(L"errors\*(R" encountered at compile time were by necessity generated as warnings followed by eventual termination of the program. This enabled more such errors to be reported in a single run, rather than causing a hard stop at the first error that was encountered. .PP The mechanism for reporting such errors has been reimplemented to queue compile-time errors and report them at the end of the compilation as true errors rather than as warnings. This fixes cases where error messages leaked through in the form of warnings when code was compiled at run time using \f(CW\*(C`eval STRING\*(C'\fR, and also allows such errors to be reliably trapped using \f(CW\*(C`eval "..."\*(C'\fR. .SS "Implicitly closed filehandles are safer" .IX Subsection "Implicitly closed filehandles are safer" Sometimes implicitly closed filehandles (as when they are localized, and Perl automatically closes them on exiting the scope) could inadvertently set $? or $!. This has been corrected. .SS "Behavior of list slices is more consistent" .IX Subsection "Behavior of list slices is more consistent" When taking a slice of a literal list (as opposed to a slice of an array or hash), Perl used to return an empty list if the result happened to be composed of all undef values. .PP The new behavior is to produce an empty list if (and only if) the original list was empty. Consider the following example: .PP .Vb 1 \& @a = (1,undef,undef,2)[2,1,2]; .Ve .PP The old behavior would have resulted in \f(CW@a\fR having no elements. The new behavior ensures it has three undefined elements. .PP Note in particular that the behavior of slices of the following cases remains unchanged: .PP .Vb 5 \& @a = ()[1,2]; \& @a = (getpwent)[7,0]; \& @a = (anything_returning_empty_list())[2,1,2]; \& @a = @b[2,1,2]; \& @a = @c{\*(Aqa\*(Aq,\*(Aqb\*(Aq,\*(Aqc\*(Aq}; .Ve .PP See perldata. .ie n .SS """(\e$)"" prototype and $foo{a}" .el .SS "\f(CW(\e$)\fP prototype and \f(CW$foo{a}\fP" .IX Subsection "($) prototype and $foo{a}" A scalar reference prototype now correctly allows a hash or array element in that slot. .ie n .SS """goto &sub"" and \s-1AUTOLOAD\s0" .el .SS "\f(CWgoto &sub\fP and \s-1AUTOLOAD\s0" .IX Subsection "goto &sub and AUTOLOAD" The \f(CW\*(C`goto &sub\*(C'\fR construct works correctly when \f(CW&sub\fR happens to be autoloaded. .ie n .SS """\-bareword"" allowed under ""use integer""" .el .SS "\f(CW\-bareword\fP allowed under \f(CWuse integer\fP" .IX Subsection "-bareword allowed under use integer" The autoquoting of barewords preceded by \f(CW\*(C`\-\*(C'\fR did not work in prior versions when the \f(CW\*(C`integer\*(C'\fR pragma was enabled. This has been fixed. .SS "Failures in \s-1\fIDESTROY\s0()\fP" .IX Subsection "Failures in DESTROY()" When code in a destructor threw an exception, it went unnoticed in earlier versions of Perl, unless someone happened to be looking in $@ just after the point the destructor happened to run. Such failures are now visible as warnings when warnings are enabled. .SS "Locale bugs fixed" .IX Subsection "Locale bugs fixed" \&\fIprintf()\fR and \fIsprintf()\fR previously reset the numeric locale back to the default \*(L"C\*(R" locale. This has been fixed. .PP Numbers formatted according to the local numeric locale (such as using a decimal comma instead of a decimal dot) caused \&\*(L"isn't numeric\*(R" warnings, even while the operations accessing those numbers produced correct results. These warnings have been discontinued. .SS "Memory leaks" .IX Subsection "Memory leaks" The \f(CW\*(C`eval \*(Aqreturn sub {...}\*(Aq\*(C'\fR construct could sometimes leak memory. This has been fixed. .PP Operations that aren't filehandle constructors used to leak memory when used on invalid filehandles. This has been fixed. .PP Constructs that modified \f(CW@_\fR could fail to deallocate values in \f(CW@_\fR and thus leak memory. This has been corrected. .SS "Spurious subroutine stubs after failed subroutine calls" .IX Subsection "Spurious subroutine stubs after failed subroutine calls" Perl could sometimes create empty subroutine stubs when a subroutine was not found in the package. Such cases stopped later method lookups from progressing into base packages. This has been corrected. .ie n .SS "Taint failures under ""\-U""" .el .SS "Taint failures under \f(CW\-U\fP" .IX Subsection "Taint failures under -U" When running in unsafe mode, taint violations could sometimes cause silent failures. This has been fixed. .ie n .SS "\s-1END\s0 blocks and the ""\-c"" switch" .el .SS "\s-1END\s0 blocks and the \f(CW\-c\fP switch" .IX Subsection "END blocks and the -c switch" Prior versions used to run \s-1BEGIN\s0 \fBand\fR \s-1END\s0 blocks when Perl was run in compile-only mode. Since this is typically not the expected behavior, \s-1END\s0 blocks are not executed anymore when the \f(CW\*(C`\-c\*(C'\fR switch is used, or if compilation fails. .PP See \*(L"Support for \s-1CHECK\s0 blocks\*(R" for how to run things when the compile phase ends. .SS "Potential to leak \s-1DATA\s0 filehandles" .IX Subsection "Potential to leak DATA filehandles" Using the \f(CW\*(C`_\|_DATA_\|_\*(C'\fR token creates an implicit filehandle to the file that contains the token. It is the program's responsibility to close it when it is done reading from it. .PP This caveat is now better explained in the documentation. See perldata. .SH "New or Changed Diagnostics" .IX Header "New or Changed Diagnostics" .ie n .IP """%s"" variable %s masks earlier declaration in same %s" 4 .el .IP "``%s'' variable \f(CW%s\fR masks earlier declaration in same \f(CW%s\fR" 4 .IX Item "%s variable %s masks earlier declaration in same %s" (W misc) A \*(L"my\*(R" or \*(L"our\*(R" variable has been redeclared in the current scope or statement, effectively eliminating all access to the previous instance. This is almost always a typographical error. Note that the earlier variable will still exist until the end of the scope or until all closure referents to it are destroyed. .ie n .IP """my sub"" not yet implemented" 4 .el .IP "``my sub'' not yet implemented" 4 .IX Item "my sub not yet implemented" (F) Lexically scoped subroutines are not yet implemented. Don't try that yet. .ie n .IP """our"" variable %s redeclared" 4 .el .IP "``our'' variable \f(CW%s\fR redeclared" 4 .IX Item "our variable %s redeclared" (W misc) You seem to have already declared the same global once before in the current lexical scope. .ie n .IP "'!' allowed only after types %s" 4 .el .IP "'!' allowed only after types \f(CW%s\fR" 4 .IX Item "'!' allowed only after types %s" (F) The '!' is allowed in \fIpack()\fR and \fIunpack()\fR only after certain types. See \*(L"pack\*(R" in perlfunc. .IP "/ cannot take a count" 4 .IX Item "/ cannot take a count" (F) You had an unpack template indicating a counted-length string, but you have also specified an explicit size for the string. See \*(L"pack\*(R" in perlfunc. .IP "/ must be followed by a, A or Z" 4 .IX Item "/ must be followed by a, A or Z" (F) You had an unpack template indicating a counted-length string, which must be followed by one of the letters a, A or Z to indicate what sort of string is to be unpacked. See \*(L"pack\*(R" in perlfunc. .IP "/ must be followed by a*, A* or Z*" 4 .IX Item "/ must be followed by a*, A* or Z*" (F) You had a pack template indicating a counted-length string, Currently the only things that can have their length counted are a*, A* or Z*. See \*(L"pack\*(R" in perlfunc. .IP "/ must follow a numeric type" 4 .IX Item "/ must follow a numeric type" (F) You had an unpack template that contained a '#', but this did not follow some numeric unpack specification. See \*(L"pack\*(R" in perlfunc. .IP "/%s/: Unrecognized escape \e\e%c passed through" 4 .IX Item "/%s/: Unrecognized escape %c passed through" (W regexp) You used a backslash-character combination which is not recognized by Perl. This combination appears in an interpolated variable or a \&\f(CW\*(C`\*(Aq\*(C'\fR\-delimited regular expression. The character was understood literally. .IP "/%s/: Unrecognized escape \e\e%c in character class passed through" 4 .IX Item "/%s/: Unrecognized escape %c in character class passed through" (W regexp) You used a backslash-character combination which is not recognized by Perl inside character classes. The character was understood literally. .ie n .IP "/%s/ should probably be written as ""%s""" 4 .el .IP "/%s/ should probably be written as ``%s''" 4 .IX Item "/%s/ should probably be written as %s" (W syntax) You have used a pattern where Perl expected to find a string, as in the first argument to \f(CW\*(C`join\*(C'\fR. Perl will treat the true or false result of matching the pattern against \f(CW$_\fR as the string, which is probably not what you had in mind. .IP "%s() called too early to check prototype" 4 .IX Item "%s() called too early to check prototype" (W prototype) You've called a function that has a prototype before the parser saw a definition or declaration for it, and Perl could not check that the call conforms to the prototype. You need to either add an early prototype declaration for the subroutine in question, or move the subroutine definition ahead of the call to get proper prototype checking. Alternatively, if you are certain that you're calling the function correctly, you may put an ampersand before the name to avoid the warning. See perlsub. .ie n .IP "%s argument is not a \s-1HASH\s0 or \s-1ARRAY\s0 element" 4 .el .IP "\f(CW%s\fR argument is not a \s-1HASH\s0 or \s-1ARRAY\s0 element" 4 .IX Item "%s argument is not a HASH or ARRAY element" (F) The argument to \fIexists()\fR must be a hash or array element, such as: .Sp .Vb 2 \& $foo{$bar} \& $ref\->{"susie"}[12] .Ve .ie n .IP "%s argument is not a \s-1HASH\s0 or \s-1ARRAY\s0 element or slice" 4 .el .IP "\f(CW%s\fR argument is not a \s-1HASH\s0 or \s-1ARRAY\s0 element or slice" 4 .IX Item "%s argument is not a HASH or ARRAY element or slice" (F) The argument to \fIdelete()\fR must be either a hash or array element, such as: .Sp .Vb 2 \& $foo{$bar} \& $ref\->{"susie"}[12] .Ve .Sp or a hash or array slice, such as: .Sp .Vb 2 \& @foo[$bar, $baz, $xyzzy] \& @{$ref\->[12]}{"susie", "queue"} .Ve .ie n .IP "%s argument is not a subroutine name" 4 .el .IP "\f(CW%s\fR argument is not a subroutine name" 4 .IX Item "%s argument is not a subroutine name" (F) The argument to \fIexists()\fR for \f(CW\*(C`exists &sub\*(C'\fR must be a subroutine name, and not a subroutine call. \f(CW\*(C`exists &sub()\*(C'\fR will generate this error. .ie n .IP "%s package attribute may clash with future reserved word: %s" 4 .el .IP "\f(CW%s\fR package attribute may clash with future reserved word: \f(CW%s\fR" 4 .IX Item "%s package attribute may clash with future reserved word: %s" (W reserved) A lowercase attribute name was used that had a package-specific handler. That name might have a meaning to Perl itself some day, even though it doesn't yet. Perhaps you should use a mixed-case attribute name, instead. See attributes. .ie n .IP "(in cleanup) %s" 4 .el .IP "(in cleanup) \f(CW%s\fR" 4 .IX Item "(in cleanup) %s" (W misc) This prefix usually indicates that a \s-1\fIDESTROY\s0()\fR method raised the indicated exception. Since destructors are usually called by the system at arbitrary points during execution, and often a vast number of times, the warning is issued only once for any number of failures that would otherwise result in the same message being repeated. .Sp Failure of user callbacks dispatched using the \f(CW\*(C`G_KEEPERR\*(C'\fR flag could also result in this warning. See \*(L"G_KEEPERR\*(R" in perlcall. .IP "<> should be quotes" 4 .IX Item "<> should be quotes" (F) You wrote \f(CW\*(C`require <file>\*(C'\fR when you should have written \&\f(CW\*(C`require \*(Aqfile\*(Aq\*(C'\fR. .IP "Attempt to join self" 4 .IX Item "Attempt to join self" (F) You tried to join a thread from within itself, which is an impossible task. You may be joining the wrong thread, or you may need to move the \fIjoin()\fR to some other thread. .IP "Bad evalled substitution pattern" 4 .IX Item "Bad evalled substitution pattern" (F) You've used the /e switch to evaluate the replacement for a substitution, but perl found a syntax error in the code to evaluate, most likely an unexpected right brace '}'. .IP "Bad \fIrealloc()\fR ignored" 4 .IX Item "Bad realloc() ignored" (S) An internal routine called \fIrealloc()\fR on something that had never been \&\fImalloc()\fRed in the first place. Mandatory, but can be disabled by setting environment variable \f(CW\*(C`PERL_BADFREE\*(C'\fR to 1. .IP "Bareword found in conditional" 4 .IX Item "Bareword found in conditional" (W bareword) The compiler found a bareword where it expected a conditional, which often indicates that an || or && was parsed as part of the last argument of the previous construct, for example: .Sp .Vb 1 \& open FOO || die; .Ve .Sp It may also indicate a misspelled constant that has been interpreted as a bareword: .Sp .Vb 2 \& use constant TYPO => 1; \& if (TYOP) { print "foo" } .Ve .Sp The \f(CW\*(C`strict\*(C'\fR pragma is useful in avoiding such errors. .IP "Binary number > 0b11111111111111111111111111111111 non-portable" 4 .IX Item "Binary number > 0b11111111111111111111111111111111 non-portable" (W portable) The binary number you specified is larger than 2**32\-1 (4294967295) and therefore non-portable between systems. See perlport for more on portability concerns. .IP "Bit vector size > 32 non-portable" 4 .IX Item "Bit vector size > 32 non-portable" (W portable) Using bit vector sizes larger than 32 is non-portable. .ie n .IP "Buffer overflow in prime_env_iter: %s" 4 .el .IP "Buffer overflow in prime_env_iter: \f(CW%s\fR" 4 .IX Item "Buffer overflow in prime_env_iter: %s" (W internal) A warning peculiar to \s-1VMS\s0. While Perl was preparing to iterate over \&\f(CW%ENV\fR, it encountered a logical name or symbol definition which was too long, so it was truncated to the string shown. .ie n .IP "Can't check filesystem of script ""%s""" 4 .el .IP "Can't check filesystem of script ``%s''" 4 .IX Item "Can't check filesystem of script %s" (P) For some reason you can't check the filesystem of the script for nosuid. .ie n .IP "Can't declare class for non-scalar %s in ""%s""" 4 .el .IP "Can't declare class for non-scalar \f(CW%s\fR in ``%s''" 4 .IX Item "Can't declare class for non-scalar %s in %s" (S) Currently, only scalar variables can declared with a specific class qualifier in a \*(L"my\*(R" or \*(L"our\*(R" declaration. The semantics may be extended for other types of variables in future. .ie n .IP "Can't declare %s in ""%s""" 4 .el .IP "Can't declare \f(CW%s\fR in ``%s''" 4 .IX Item "Can't declare %s in %s" (F) Only scalar, array, and hash variables may be declared as \*(L"my\*(R" or \&\*(L"our\*(R" variables. They must have ordinary identifiers as names. .IP "Can't ignore signal \s-1CHLD\s0, forcing to default" 4 .IX Item "Can't ignore signal CHLD, forcing to default" (W signal) Perl has detected that it is being run with the \s-1SIGCHLD\s0 signal (sometimes known as \s-1SIGCLD\s0) disabled. Since disabling this signal will interfere with proper determination of exit status of child processes, Perl has reset the signal to its default value. This situation typically indicates that the parent program under which Perl may be running (e.g., cron) is being very careless. .IP "Can't modify non-lvalue subroutine call" 4 .IX Item "Can't modify non-lvalue subroutine call" (F) Subroutines meant to be used in lvalue context should be declared as such, see \*(L"Lvalue subroutines\*(R" in perlsub. .IP "Can't read \s-1CRTL\s0 environ" 4 .IX Item "Can't read CRTL environ" (S) A warning peculiar to \s-1VMS\s0. Perl tried to read an element of \f(CW%ENV\fR from the \s-1CRTL\s0's internal environment array and discovered the array was missing. You need to figure out where your \s-1CRTL\s0 misplaced its environ or define \fI\s-1PERL_ENV_TABLES\s0\fR (see perlvms) so that environ is not searched. .ie n .IP "Can't remove %s: %s, skipping file" 4 .el .IP "Can't remove \f(CW%s:\fR \f(CW%s\fR, skipping file" 4 .IX Item "Can't remove %s: %s, skipping file" (S) You requested an inplace edit without creating a backup file. Perl was unable to remove the original file to replace it with the modified file. The file was left unmodified. .ie n .IP "Can't return %s from lvalue subroutine" 4 .el .IP "Can't return \f(CW%s\fR from lvalue subroutine" 4 .IX Item "Can't return %s from lvalue subroutine" (F) Perl detected an attempt to return illegal lvalues (such as temporary or readonly values) from a subroutine used as an lvalue. This is not allowed. .IP "Can't weaken a nonreference" 4 .IX Item "Can't weaken a nonreference" (F) You attempted to weaken something that was not a reference. Only references can be weakened. .IP "Character class [:%s:] unknown" 4 .IX Item "Character class [:%s:] unknown" (F) The class in the character class [: :] syntax is unknown. See perlre. .IP "Character class syntax [%s] belongs inside character classes" 4 .IX Item "Character class syntax [%s] belongs inside character classes" (W unsafe) The character class constructs [: :], [= =], and [. .] go \&\fIinside\fR character classes, the [] are part of the construct, for example: /[012[:alpha:]345]/. Note that [= =] and [. .] are not currently implemented; they are simply placeholders for future extensions. .ie n .IP "Constant is not %s reference" 4 .el .IP "Constant is not \f(CW%s\fR reference" 4 .IX Item "Constant is not %s reference" (F) A constant value (perhaps declared using the \f(CW\*(C`use constant\*(C'\fR pragma) is being dereferenced, but it amounts to the wrong type of reference. The message indicates the type of reference that was expected. This usually indicates a syntax error in dereferencing the constant value. See \*(L"Constant Functions\*(R" in perlsub and constant. .ie n .IP "constant(%s): %s" 4 .el .IP "constant(%s): \f(CW%s\fR" 4 .IX Item "constant(%s): %s" (F) The parser found inconsistencies either while attempting to define an overloaded constant, or when trying to find the character name specified in the \f(CW\*(C`\eN{...}\*(C'\fR escape. Perhaps you forgot to load the corresponding \&\f(CW\*(C`overload\*(C'\fR or \f(CW\*(C`charnames\*(C'\fR pragma? See charnames and overload. .IP "CORE::%s is not a keyword" 4 .IX Item "CORE::%s is not a keyword" (F) The \s-1CORE::\s0 namespace is reserved for Perl keywords. .IP "defined(@array) is deprecated" 4 .IX Item "defined(@array) is deprecated" (D) \fIdefined()\fR is not usually useful on arrays because it checks for an undefined \fIscalar\fR value. If you want to see if the array is empty, just use \f(CW\*(C`if (@array) { # not empty }\*(C'\fR for example. .IP "defined(%hash) is deprecated" 4 .IX Item "defined(%hash) is deprecated" (D) \fIdefined()\fR is not usually useful on hashes because it checks for an undefined \fIscalar\fR value. If you want to see if the hash is empty, just use \f(CW\*(C`if (%hash) { # not empty }\*(C'\fR for example. .IP "Did not produce a valid header" 4 .IX Item "Did not produce a valid header" See Server error. .ie n .IP "(Did you mean ""local"" instead of ""our""?)" 4 .el .IP "(Did you mean ``local'' instead of ``our''?)" 4 .IX Item "(Did you mean local instead of our?)" (W misc) Remember that \*(L"our\*(R" does not localize the declared global variable. You have declared it again in the same lexical scope, which seems superfluous. .IP "Document contains no data" 4 .IX Item "Document contains no data" See Server error. .ie n .IP "entering effective %s failed" 4 .el .IP "entering effective \f(CW%s\fR failed" 4 .IX Item "entering effective %s failed" (F) While under the \f(CW\*(C`use filetest\*(C'\fR pragma, switching the real and effective uids or gids failed. .ie n .IP "false [] range ""%s"" in regexp" 4 .el .IP "false [] range ``%s'' in regexp" 4 .IX Item "false [] range %s in regexp" (W regexp) A character class range must start and end at a literal character, not another character class like \f(CW\*(C`\ed\*(C'\fR or \f(CW\*(C`[:alpha:]\*(C'\fR. The \*(L"\-\*(R" in your false range is interpreted as a literal \*(L"\-\*(R". Consider quoting the \*(L"\-\*(R", \*(L"\e\-\*(R". See perlre. .ie n .IP "Filehandle %s opened only for output" 4 .el .IP "Filehandle \f(CW%s\fR opened only for output" 4 .IX Item "Filehandle %s opened only for output" (W io) You tried to read from a filehandle opened only for writing. If you intended it to be a read/write filehandle, you needed to open it with \&\*(L"+<\*(R" or \*(L"+>\*(R" or \*(L"+>>\*(R" instead of with \*(L"<\*(R" or nothing. If you intended only to read from the file, use \*(L"<\*(R". See \&\*(L"open\*(R" in perlfunc. .ie n .IP "\fIflock()\fR on closed filehandle %s" 4 .el .IP "\fIflock()\fR on closed filehandle \f(CW%s\fR" 4 .IX Item "flock() on closed filehandle %s" (W closed) The filehandle you're attempting to \fIflock()\fR got itself closed some time before now. Check your logic flow. \fIflock()\fR operates on filehandles. Are you attempting to call \fIflock()\fR on a dirhandle by the same name? .ie n .IP "Global symbol ""%s"" requires explicit package name" 4 .el .IP "Global symbol ``%s'' requires explicit package name" 4 .IX Item "Global symbol %s requires explicit package name" (F) You've said \*(L"use strict vars\*(R", which indicates that all variables must either be lexically scoped (using \*(L"my\*(R"), declared beforehand using \&\*(L"our\*(R", or explicitly qualified to say which package the global variable is in (using \*(L"::\*(R"). .IP "Hexadecimal number > 0xffffffff non-portable" 4 .IX Item "Hexadecimal number > 0xffffffff non-portable" (W portable) The hexadecimal number you specified is larger than 2**32\-1 (4294967295) and therefore non-portable between systems. See perlport for more on portability concerns. .ie n .IP "Ill-formed \s-1CRTL\s0 environ value ""%s""" 4 .el .IP "Ill-formed \s-1CRTL\s0 environ value ``%s''" 4 .IX Item "Ill-formed CRTL environ value %s" (W internal) A warning peculiar to \s-1VMS\s0. Perl tried to read the \s-1CRTL\s0's internal environ array, and encountered an element without the \f(CW\*(C`=\*(C'\fR delimiter used to separate keys from values. The element is ignored. .IP "Ill-formed message in prime_env_iter: |%s|" 4 .IX Item "Ill-formed message in prime_env_iter: |%s|" (W internal) A warning peculiar to \s-1VMS\s0. Perl tried to read a logical name or \s-1CLI\s0 symbol definition when preparing to iterate over \f(CW%ENV\fR, and didn't see the expected delimiter between key and value, so the line was ignored. .ie n .IP "Illegal binary digit %s" 4 .el .IP "Illegal binary digit \f(CW%s\fR" 4 .IX Item "Illegal binary digit %s" (F) You used a digit other than 0 or 1 in a binary number. .ie n .IP "Illegal binary digit %s ignored" 4 .el .IP "Illegal binary digit \f(CW%s\fR ignored" 4 .IX Item "Illegal binary digit %s ignored" (W digit) You may have tried to use a digit other than 0 or 1 in a binary number. Interpretation of the binary number stopped before the offending digit. .IP "Illegal number of bits in vec" 4 .IX Item "Illegal number of bits in vec" (F) The number of bits in \fIvec()\fR (the third argument) must be a power of two from 1 to 32 (or 64, if your platform supports that). .ie n .IP "Integer overflow in %s number" 4 .el .IP "Integer overflow in \f(CW%s\fR number" 4 .IX Item "Integer overflow in %s number" (W overflow) The hexadecimal, octal or binary number you have specified either as a literal or as an argument to \fIhex()\fR or \fIoct()\fR is too big for your architecture, and has been converted to a floating point number. On a 32\-bit architecture the largest hexadecimal, octal or binary number representable without overflow is 0xFFFFFFFF, 037777777777, or 0b11111111111111111111111111111111 respectively. Note that Perl transparently promotes all numbers to a floating point representation internally\*(--subject to loss of precision errors in subsequent operations. .ie n .IP "Invalid %s attribute: %s" 4 .el .IP "Invalid \f(CW%s\fR attribute: \f(CW%s\fR" 4 .IX Item "Invalid %s attribute: %s" The indicated attribute for a subroutine or variable was not recognized by Perl or by a user-supplied handler. See attributes. .ie n .IP "Invalid %s attributes: %s" 4 .el .IP "Invalid \f(CW%s\fR attributes: \f(CW%s\fR" 4 .IX Item "Invalid %s attributes: %s" The indicated attributes for a subroutine or variable were not recognized by Perl or by a user-supplied handler. See attributes. .ie n .IP "invalid [] range ""%s"" in regexp" 4 .el .IP "invalid [] range ``%s'' in regexp" 4 .IX Item "invalid [] range %s in regexp" The offending range is now explicitly displayed. .ie n .IP "Invalid separator character %s in attribute list" 4 .el .IP "Invalid separator character \f(CW%s\fR in attribute list" 4 .IX Item "Invalid separator character %s in attribute list" (F) Something other than a colon or whitespace was seen between the elements of an attribute list. If the previous attribute had a parenthesised parameter list, perhaps that list was terminated too soon. See attributes. .ie n .IP "Invalid separator character %s in subroutine attribute list" 4 .el .IP "Invalid separator character \f(CW%s\fR in subroutine attribute list" 4 .IX Item "Invalid separator character %s in subroutine attribute list" (F) Something other than a colon or whitespace was seen between the elements of a subroutine attribute list. If the previous attribute had a parenthesised parameter list, perhaps that list was terminated too soon. .ie n .IP "leaving effective %s failed" 4 .el .IP "leaving effective \f(CW%s\fR failed" 4 .IX Item "leaving effective %s failed" (F) While under the \f(CW\*(C`use filetest\*(C'\fR pragma, switching the real and effective uids or gids failed. .ie n .IP "Lvalue subs returning %s not implemented yet" 4 .el .IP "Lvalue subs returning \f(CW%s\fR not implemented yet" 4 .IX Item "Lvalue subs returning %s not implemented yet" (F) Due to limitations in the current implementation, array and hash values cannot be returned in subroutines used in lvalue context. See \*(L"Lvalue subroutines\*(R" in perlsub. .ie n .IP "Method %s not permitted" 4 .el .IP "Method \f(CW%s\fR not permitted" 4 .IX Item "Method %s not permitted" See Server error. .ie n .IP "Missing %sbrace%s on \eN{}" 4 .el .IP "Missing \f(CW%sbrace\fR%s on \eN{}" 4 .IX Item "Missing %sbrace%s on N{}" (F) Wrong syntax of character name literal \f(CW\*(C`\eN{charname}\*(C'\fR within double-quotish context. .IP "Missing command in piped open" 4 .IX Item "Missing command in piped open" (W pipe) You used the \f(CW\*(C`open(FH, "| command")\*(C'\fR or \f(CW\*(C`open(FH, "command |")\*(C'\fR construction, but the command was missing or blank. .ie n .IP "Missing name in ""my sub""" 4 .el .IP "Missing name in ``my sub''" 4 .IX Item "Missing name in my sub" (F) The reserved syntax for lexically scoped subroutines requires that they have a name with which they can be found. .ie n .IP "No %s specified for \-%c" 4 .el .IP "No \f(CW%s\fR specified for \-%c" 4 .IX Item "No %s specified for -%c" (F) The indicated command line switch needs a mandatory argument, but you haven't specified one. .ie n .IP "No package name allowed for variable %s in ""our""" 4 .el .IP "No package name allowed for variable \f(CW%s\fR in ``our''" 4 .IX Item "No package name allowed for variable %s in our" (F) Fully qualified variable names are not allowed in \*(L"our\*(R" declarations, because that doesn't make much sense under existing semantics. Such syntax is reserved for future extensions. .IP "No space allowed after \-%c" 4 .IX Item "No space allowed after -%c" (F) The argument to the indicated command line switch must follow immediately after the switch, without intervening spaces. .IP "no \s-1UTC\s0 offset information; assuming local time is \s-1UTC\s0" 4 .IX Item "no UTC offset information; assuming local time is UTC" (S) A warning peculiar to \s-1VMS\s0. Perl was unable to find the local timezone offset, so it's assuming that local system time is equivalent to \s-1UTC\s0. If it's not, define the logical name \fI\s-1SYS$TIMEZONE_DIFFERENTIAL\s0\fR to translate to the number of seconds which need to be added to \s-1UTC\s0 to get local time. .IP "Octal number > 037777777777 non-portable" 4 .IX Item "Octal number > 037777777777 non-portable" (W portable) The octal number you specified is larger than 2**32\-1 (4294967295) and therefore non-portable between systems. See perlport for more on portability concerns. .Sp See also perlport for writing portable code. .IP "panic: del_backref" 4 .IX Item "panic: del_backref" (P) Failed an internal consistency check while trying to reset a weak reference. .IP "panic: kid popen errno read" 4 .IX Item "panic: kid popen errno read" (F) forked child returned an incomprehensible message about its errno. .IP "panic: magic_killbackrefs" 4 .IX Item "panic: magic_killbackrefs" (P) Failed an internal consistency check while trying to reset all weak references to an object. .ie n .IP "Parentheses missing around ""%s"" list" 4 .el .IP "Parentheses missing around ``%s'' list" 4 .IX Item "Parentheses missing around %s list" (W parenthesis) You said something like .Sp .Vb 1 \& my $foo, $bar = @_; .Ve .Sp when you meant .Sp .Vb 1 \& my ($foo, $bar) = @_; .Ve .Sp Remember that \*(L"my\*(R", \*(L"our\*(R", and \*(L"local\*(R" bind tighter than comma. .ie n .IP "Possible unintended interpolation of %s in string" 4 .el .IP "Possible unintended interpolation of \f(CW%s\fR in string" 4 .IX Item "Possible unintended interpolation of %s in string" (W ambiguous) It used to be that Perl would try to guess whether you wanted an array interpolated or a literal @. It no longer does this; arrays are now \fIalways\fR interpolated into strings. This means that if you try something like: .Sp .Vb 1 \& print "fred@example.com"; .Ve .Sp and the array \f(CW@example\fR doesn't exist, Perl is going to print \&\f(CW\*(C`fred.com\*(C'\fR, which is probably not what you wanted. To get a literal \&\f(CW\*(C`@\*(C'\fR sign in a string, put a backslash before it, just as you would to get a literal \f(CW\*(C`$\*(C'\fR sign. .ie n .IP "Possible Y2K bug: %s" 4 .el .IP "Possible Y2K bug: \f(CW%s\fR" 4 .IX Item "Possible Y2K bug: %s" (W y2k) You are concatenating the number 19 with another number, which could be a potential Year 2000 problem. .ie n .IP "pragma ""attrs"" is deprecated, use ""sub \s-1NAME\s0 : \s-1ATTRS\s0"" instead" 4 .el .IP "pragma ``attrs'' is deprecated, use ``sub \s-1NAME\s0 : \s-1ATTRS\s0'' instead" 4 .IX Item "pragma attrs is deprecated, use sub NAME : ATTRS instead" (W deprecated) You have written something like this: .Sp .Vb 4 \& sub doit \& { \& use attrs qw(locked); \& } .Ve .Sp You should use the new declaration syntax instead. .Sp .Vb 3 \& sub doit : locked \& { \& ... .Ve .Sp The \f(CW\*(C`use attrs\*(C'\fR pragma is now obsolete, and is only provided for backward-compatibility. See \*(L"Subroutine Attributes\*(R" in perlsub. .IP "Premature end of script headers" 4 .IX Item "Premature end of script headers" See Server error. .IP "Repeat count in pack overflows" 4 .IX Item "Repeat count in pack overflows" (F) You can't specify a repeat count so large that it overflows your signed integers. See \*(L"pack\*(R" in perlfunc. .IP "Repeat count in unpack overflows" 4 .IX Item "Repeat count in unpack overflows" (F) You can't specify a repeat count so large that it overflows your signed integers. See \*(L"unpack\*(R" in perlfunc. .IP "\fIrealloc()\fR of freed memory ignored" 4 .IX Item "realloc() of freed memory ignored" (S) An internal routine called \fIrealloc()\fR on something that had already been freed. .IP "Reference is already weak" 4 .IX Item "Reference is already weak" (W misc) You have attempted to weaken a reference that is already weak. Doing so has no effect. .IP "setpgrp can't take arguments" 4 .IX Item "setpgrp can't take arguments" (F) Your system has the \fIsetpgrp()\fR from \s-1BSD\s0 4.2, which takes no arguments, unlike \s-1POSIX\s0 \fIsetpgid()\fR, which takes a process \s-1ID\s0 and process group \s-1ID\s0. .IP "Strange *+?{} on zero-length expression" 4 .IX Item "Strange *+?{} on zero-length expression" (W regexp) You applied a regular expression quantifier in a place where it makes no sense, such as on a zero-width assertion. Try putting the quantifier inside the assertion instead. For example, the way to match \*(L"abc\*(R" provided that it is followed by three repetitions of \*(L"xyz\*(R" is \f(CW\*(C`/abc(?=(?:xyz){3})/\*(C'\fR, not \f(CW\*(C`/abc(?=xyz){3}/\*(C'\fR. .ie n .IP "switching effective %s is not implemented" 4 .el .IP "switching effective \f(CW%s\fR is not implemented" 4 .IX Item "switching effective %s is not implemented" (F) While under the \f(CW\*(C`use filetest\*(C'\fR pragma, we cannot switch the real and effective uids or gids. .IP "This Perl can't reset \s-1CRTL\s0 environ elements (%s)" 4 .IX Item "This Perl can't reset CRTL environ elements (%s)" .PD 0 .IP "This Perl can't set \s-1CRTL\s0 environ elements (%s=%s)" 4 .IX Item "This Perl can't set CRTL environ elements (%s=%s)" .PD (W internal) Warnings peculiar to \s-1VMS\s0. You tried to change or delete an element of the \s-1CRTL\s0's internal environ array, but your copy of Perl wasn't built with a \s-1CRTL\s0 that contained the \fIsetenv()\fR function. You'll need to rebuild Perl with a \s-1CRTL\s0 that does, or redefine \fI\s-1PERL_ENV_TABLES\s0\fR (see perlvms) so that the environ array isn't the target of the change to \&\f(CW%ENV\fR which produced the warning. .ie n .IP "Too late to run %s block" 4 .el .IP "Too late to run \f(CW%s\fR block" 4 .IX Item "Too late to run %s block" (W void) A \s-1CHECK\s0 or \s-1INIT\s0 block is being defined during run time proper, when the opportunity to run them has already passed. Perhaps you are loading a file with \f(CW\*(C`require\*(C'\fR or \f(CW\*(C`do\*(C'\fR when you should be using \&\f(CW\*(C`use\*(C'\fR instead. Or perhaps you should put the \f(CW\*(C`require\*(C'\fR or \f(CW\*(C`do\*(C'\fR inside a \s-1BEGIN\s0 block. .IP "Unknown \fIopen()\fR mode '%s'" 4 .IX Item "Unknown open() mode '%s'" (F) The second argument of 3\-argument \fIopen()\fR is not among the list of valid modes: \f(CW\*(C`<\*(C'\fR, \f(CW\*(C`>\*(C'\fR, \f(CW\*(C`>>\*(C'\fR, \f(CW\*(C`+<\*(C'\fR, \&\f(CW\*(C`+>\*(C'\fR, \f(CW\*(C`+>>\*(C'\fR, \f(CW\*(C`\-|\*(C'\fR, \f(CW\*(C`|\-\*(C'\fR. .ie n .IP "Unknown process %x sent message to prime_env_iter: %s" 4 .el .IP "Unknown process \f(CW%x\fR sent message to prime_env_iter: \f(CW%s\fR" 4 .IX Item "Unknown process %x sent message to prime_env_iter: %s" (P) An error peculiar to \s-1VMS\s0. Perl was reading values for \f(CW%ENV\fR before iterating over it, and someone else stuck a message in the stream of data Perl expected. Someone's very confused, or perhaps trying to subvert Perl's population of \f(CW%ENV\fR for nefarious purposes. .IP "Unrecognized escape \e\e%c passed through" 4 .IX Item "Unrecognized escape %c passed through" (W misc) You used a backslash-character combination which is not recognized by Perl. The character was understood literally. .IP "Unterminated attribute parameter in attribute list" 4 .IX Item "Unterminated attribute parameter in attribute list" (F) The lexer saw an opening (left) parenthesis character while parsing an attribute list, but the matching closing (right) parenthesis character was not found. You may need to add (or remove) a backslash character to get your parentheses to balance. See attributes. .IP "Unterminated attribute list" 4 .IX Item "Unterminated attribute list" (F) The lexer found something other than a simple identifier at the start of an attribute, and it wasn't a semicolon or the start of a block. Perhaps you terminated the parameter list of the previous attribute too soon. See attributes. .IP "Unterminated attribute parameter in subroutine attribute list" 4 .IX Item "Unterminated attribute parameter in subroutine attribute list" (F) The lexer saw an opening (left) parenthesis character while parsing a subroutine attribute list, but the matching closing (right) parenthesis character was not found. You may need to add (or remove) a backslash character to get your parentheses to balance. .IP "Unterminated subroutine attribute list" 4 .IX Item "Unterminated subroutine attribute list" (F) The lexer found something other than a simple identifier at the start of a subroutine attribute, and it wasn't a semicolon or the start of a block. Perhaps you terminated the parameter list of the previous attribute too soon. .ie n .IP "Value of \s-1CLI\s0 symbol ""%s"" too long" 4 .el .IP "Value of \s-1CLI\s0 symbol ``%s'' too long" 4 .IX Item "Value of CLI symbol %s too long" (W misc) A warning peculiar to \s-1VMS\s0. Perl tried to read the value of an \f(CW%ENV\fR element from a \s-1CLI\s0 symbol table, and found a resultant string longer than 1024 characters. The return value has been truncated to 1024 characters. .IP "Version number must be a constant number" 4 .IX Item "Version number must be a constant number" (P) The attempt to translate a \f(CW\*(C`use Module n.n LIST\*(C'\fR statement into its equivalent \f(CW\*(C`BEGIN\*(C'\fR block found an internal inconsistency with the version number. .SH "New tests" .IX Header "New tests" .IP "lib/attrs" 4 .IX Item "lib/attrs" Compatibility tests for \f(CW\*(C`sub : attrs\*(C'\fR vs the older \f(CW\*(C`use attrs\*(C'\fR. .IP "lib/env" 4 .IX Item "lib/env" Tests for new environment scalar capability (e.g., \f(CW\*(C`use Env qw($BAR);\*(C'\fR). .IP "lib/env\-array" 4 .IX Item "lib/env-array" Tests for new environment array capability (e.g., \f(CW\*(C`use Env qw(@PATH);\*(C'\fR). .IP "lib/io_const" 4 .IX Item "lib/io_const" \&\s-1IO\s0 constants (SEEK_*, _IO*). .IP "lib/io_dir" 4 .IX Item "lib/io_dir" Directory-related \s-1IO\s0 methods (new, read, close, rewind, tied delete). .IP "lib/io_multihomed" 4 .IX Item "lib/io_multihomed" \&\s-1INET\s0 sockets with multi-homed hosts. .IP "lib/io_poll" 4 .IX Item "lib/io_poll" \&\s-1IO\s0 \fIpoll()\fR. .IP "lib/io_unix" 4 .IX Item "lib/io_unix" \&\s-1UNIX\s0 sockets. .IP "op/attrs" 4 .IX Item "op/attrs" Regression tests for \f(CW\*(C`my ($x,@y,%z) : attrs\*(C'\fR and <sub : attrs>. .IP "op/filetest" 4 .IX Item "op/filetest" File test operators. .IP "op/lex_assign" 4 .IX Item "op/lex_assign" Verify operations that access pad objects (lexicals and temporaries). .IP "op/exists_sub" 4 .IX Item "op/exists_sub" Verify \f(CW\*(C`exists &sub\*(C'\fR operations. .SH "Incompatible Changes" .IX Header "Incompatible Changes" .SS "Perl Source Incompatibilities" .IX Subsection "Perl Source Incompatibilities" Beware that any new warnings that have been added or old ones that have been enhanced are \fBnot\fR considered incompatible changes. .PP Since all new warnings must be explicitly requested via the \f(CW\*(C`\-w\*(C'\fR switch or the \f(CW\*(C`warnings\*(C'\fR pragma, it is ultimately the programmer's responsibility to ensure that warnings are enabled judiciously. .IP "\s-1CHECK\s0 is a new keyword" 4 .IX Item "CHECK is a new keyword" All subroutine definitions named \s-1CHECK\s0 are now special. See \&\f(CW\*(C`/"Support for CHECK blocks"\*(C'\fR for more information. .IP "Treatment of list slices of undef has changed" 4 .IX Item "Treatment of list slices of undef has changed" There is a potential incompatibility in the behavior of list slices that are comprised entirely of undefined values. See \*(L"Behavior of list slices is more consistent\*(R". .ie n .IP "Format of $English::PERL_VERSION is different" 4 .el .IP "Format of \f(CW$English::PERL_VERSION\fR is different" 4 .IX Item "Format of $English::PERL_VERSION is different" The English module now sets \f(CW$PERL_VERSION\fR to $^V (a string value) rather than \f(CW$]\fR (a numeric value). This is a potential incompatibility. Send us a report via perlbug if you are affected by this. .Sp See \*(L"Improved Perl version numbering system\*(R" for the reasons for this change. .ie n .IP "Literals of the form 1.2.3 parse differently" 4 .el .IP "Literals of the form \f(CW1.2.3\fR parse differently" 4 .IX Item "Literals of the form 1.2.3 parse differently" Previously, numeric literals with more than one dot in them were interpreted as a floating point number concatenated with one or more numbers. Such \*(L"numbers\*(R" are now parsed as strings composed of the specified ordinals. .Sp For example, \f(CW\*(C`print 97.98.99\*(C'\fR used to output \f(CW97.9899\fR in earlier versions, but now prints \f(CW\*(C`abc\*(C'\fR. .Sp See \*(L"Support for strings represented as a vector of ordinals\*(R". .IP "Possibly changed pseudo-random number generator" 4 .IX Item "Possibly changed pseudo-random number generator" Perl programs that depend on reproducing a specific set of pseudo-random numbers may now produce different output due to improvements made to the \&\fIrand()\fR builtin. You can use \f(CW\*(C`sh Configure \-Drandfunc=rand\*(C'\fR to obtain the old behavior. .Sp See \*(L"Better pseudo-random number generator\*(R". .IP "Hashing function for hash keys has changed" 4 .IX Item "Hashing function for hash keys has changed" Even though Perl hashes are not order preserving, the apparently random order encountered when iterating on the contents of a hash is actually determined by the hashing algorithm used. Improvements in the algorithm may yield a random order that is \fBdifferent\fR from that of previous versions, especially when iterating on hashes. .Sp See \*(L"Better worst-case behavior of hashes\*(R" for additional information. .ie n .IP """undef"" fails on read only values" 4 .el .IP "\f(CWundef\fR fails on read only values" 4 .IX Item "undef fails on read only values" Using the \f(CW\*(C`undef\*(C'\fR operator on a readonly value (such as \f(CW$1\fR) has the same effect as assigning \f(CW\*(C`undef\*(C'\fR to the readonly value\*(--it throws an exception. .IP "Close-on-exec bit may be set on pipe and socket handles" 4 .IX Item "Close-on-exec bit may be set on pipe and socket handles" Pipe and socket handles are also now subject to the close-on-exec behavior determined by the special variable $^F. .Sp See \*(L"More consistent close-on-exec behavior\*(R". .ie n .IP "Writing ""$$1"" to mean ""${$}1"" is unsupported" 4 .el .IP "Writing \f(CW``$$1''\fR to mean \f(CW``${$}1''\fR is unsupported" 4 .IX Item "Writing ""$$1"" to mean ""${$}1"" is unsupported" Perl 5.004 deprecated the interpretation of \f(CW$$1\fR and similar within interpolated strings to mean \f(CW\*(C`$$ . "1"\*(C'\fR, but still allowed it. .Sp In Perl 5.6.0 and later, \f(CW"$$1"\fR always means \f(CW"${$1}"\fR. .ie n .IP "\fIdelete()\fR, \fIeach()\fR, \fIvalues()\fR and ""\e(%h)""" 4 .el .IP "\fIdelete()\fR, \fIeach()\fR, \fIvalues()\fR and \f(CW\e(%h)\fR" 4 .IX Item "delete(), each(), values() and )" operate on aliases to values, not copies .Sp \&\fIdelete()\fR, \fIeach()\fR, \fIvalues()\fR and hashes (e.g. \f(CW\*(C`\e(%h)\*(C'\fR) in a list context return the actual values in the hash, instead of copies (as they used to in earlier versions). Typical idioms for using these constructs copy the returned values, but this can make a significant difference when creating references to the returned values. Keys in the hash are still returned as copies when iterating on a hash. .Sp See also \*(L"\fIdelete()\fR, \fIeach()\fR, \fIvalues()\fR and hash iteration are faster\*(R". .IP "vec(\s-1EXPR\s0,OFFSET,BITS) enforces powers-of-two \s-1BITS\s0" 4 .IX Item "vec(EXPR,OFFSET,BITS) enforces powers-of-two BITS" \&\fIvec()\fR generates a run-time error if the \s-1BITS\s0 argument is not a valid power-of-two integer. .IP "Text of some diagnostic output has changed" 4 .IX Item "Text of some diagnostic output has changed" Most references to internal Perl operations in diagnostics have been changed to be more descriptive. This may be an issue for programs that may incorrectly rely on the exact text of diagnostics for proper functioning. .ie n .IP """%@"" has been removed" 4 .el .IP "\f(CW%@\fR has been removed" 4 .IX Item "%@ has been removed" The undocumented special variable \f(CW\*(C`%@\*(C'\fR that used to accumulate \&\*(L"background\*(R" errors (such as those that happen in \s-1\fIDESTROY\s0()\fR) has been removed, because it could potentially result in memory leaks. .IP "Parenthesized \fInot()\fR behaves like a list operator" 4 .IX Item "Parenthesized not() behaves like a list operator" The \f(CW\*(C`not\*(C'\fR operator now falls under the \*(L"if it looks like a function, it behaves like a function\*(R" rule. .Sp As a result, the parenthesized form can be used with \f(CW\*(C`grep\*(C'\fR and \f(CW\*(C`map\*(C'\fR. The following construct used to be a syntax error before, but it works as expected now: .Sp .Vb 1 \& grep not($_), @things; .Ve .Sp On the other hand, using \f(CW\*(C`not\*(C'\fR with a literal list slice may not work. The following previously allowed construct: .Sp .Vb 1 \& print not (1,2,3)[0]; .Ve .Sp needs to be written with additional parentheses now: .Sp .Vb 1 \& print not((1,2,3)[0]); .Ve .Sp The behavior remains unaffected when \f(CW\*(C`not\*(C'\fR is not followed by parentheses. .ie n .IP "Semantics of bareword prototype ""(*)"" have changed" 4 .el .IP "Semantics of bareword prototype \f(CW(*)\fR have changed" 4 .IX Item "Semantics of bareword prototype (*) have changed" The semantics of the bareword prototype \f(CW\*(C`*\*(C'\fR have changed. Perl 5.005 always coerced simple scalar arguments to a typeglob, which wasn't useful in situations where the subroutine must distinguish between a simple scalar and a typeglob. The new behavior is to not coerce bareword arguments to a typeglob. The value will always be visible as either a simple scalar or as a reference to a typeglob. .Sp See \*(L"More functional bareword prototype (*)\*(R". .IP "Semantics of bit operators may have changed on 64\-bit platforms" 4 .IX Item "Semantics of bit operators may have changed on 64-bit platforms" If your platform is either natively 64\-bit or if Perl has been configured to used 64\-bit integers, i.e., \f(CW$Config\fR{ivsize} is 8, there may be a potential incompatibility in the behavior of bitwise numeric operators (& | ^ ~ << >>). These operators used to strictly operate on the lower 32 bits of integers in previous versions, but now operate over the entire native integral width. In particular, note that unary \f(CW\*(C`~\*(C'\fR will produce different results on platforms that have different \f(CW$Config\fR{ivsize}. For portability, be sure to mask off the excess bits in the result of unary \f(CW\*(C`~\*(C'\fR, e.g., \f(CW\*(C`~$x & 0xffffffff\*(C'\fR. .Sp See \*(L"Bit operators support full native integer width\*(R". .IP "More builtins taint their results" 4 .IX Item "More builtins taint their results" As described in \*(L"Improved security features\*(R", there may be more sources of taint in a Perl program. .Sp To avoid these new tainting behaviors, you can build Perl with the Configure option \f(CW\*(C`\-Accflags=\-DINCOMPLETE_TAINTS\*(C'\fR. Beware that the ensuing perl binary may be insecure. .SS "C Source Incompatibilities" .IX Subsection "C Source Incompatibilities" .ie n .IP """PERL_POLLUTE""" 4 .el .IP "\f(CWPERL_POLLUTE\fR" 4 .IX Item "PERL_POLLUTE" Release 5.005 grandfathered old global symbol names by providing preprocessor macros for extension source compatibility. As of release 5.6.0, these preprocessor definitions are not available by default. You need to explicitly compile perl with \f(CW\*(C`\-DPERL_POLLUTE\*(C'\fR to get these definitions. For extensions still using the old symbols, this option can be specified via MakeMaker: .Sp .Vb 1 \& perl Makefile.PL POLLUTE=1 .Ve .ie n .IP """PERL_IMPLICIT_CONTEXT""" 4 .el .IP "\f(CWPERL_IMPLICIT_CONTEXT\fR" 4 .IX Item "PERL_IMPLICIT_CONTEXT" This new build option provides a set of macros for all \s-1API\s0 functions such that an implicit interpreter/thread context argument is passed to every \s-1API\s0 function. As a result of this, something like \f(CW\*(C`sv_setsv(foo,bar)\*(C'\fR amounts to a macro invocation that actually translates to something like \&\f(CW\*(C`Perl_sv_setsv(my_perl,foo,bar)\*(C'\fR. While this is generally expected to not have any significant source compatibility issues, the difference between a macro and a real function call will need to be considered. .Sp This means that there \fBis\fR a source compatibility issue as a result of this if your extensions attempt to use pointers to any of the Perl \s-1API\s0 functions. .Sp Note that the above issue is not relevant to the default build of Perl, whose interfaces continue to match those of prior versions (but subject to the other options described here). .Sp See \*(L"Background and \s-1PERL_IMPLICIT_CONTEXT\s0\*(R" in perlguts for detailed information on the ramifications of building Perl with this option. .Sp .Vb 3 \& NOTE: PERL_IMPLICIT_CONTEXT is automatically enabled whenever Perl is built \& with one of \-Dusethreads, \-Dusemultiplicity, or both. It is not \& intended to be enabled by users at this time. .Ve .ie n .IP """PERL_POLLUTE_MALLOC""" 4 .el .IP "\f(CWPERL_POLLUTE_MALLOC\fR" 4 .IX Item "PERL_POLLUTE_MALLOC" Enabling Perl's malloc in release 5.005 and earlier caused the namespace of the system's malloc family of functions to be usurped by the Perl versions, since by default they used the same names. Besides causing problems on platforms that do not allow these functions to be cleanly replaced, this also meant that the system versions could not be called in programs that used Perl's malloc. Previous versions of Perl have allowed this behaviour to be suppressed with the \s-1HIDEMYMALLOC\s0 and \s-1EMBEDMYMALLOC\s0 preprocessor definitions. .Sp As of release 5.6.0, Perl's malloc family of functions have default names distinct from the system versions. You need to explicitly compile perl with \&\f(CW\*(C`\-DPERL_POLLUTE_MALLOC\*(C'\fR to get the older behaviour. \s-1HIDEMYMALLOC\s0 and \s-1EMBEDMYMALLOC\s0 have no effect, since the behaviour they enabled is now the default. .Sp Note that these functions do \fBnot\fR constitute Perl's memory allocation \s-1API\s0. See \*(L"Memory Allocation\*(R" in perlguts for further information about that. .SS "Compatible C Source \s-1API\s0 Changes" .IX Subsection "Compatible C Source API Changes" .ie n .IP """PATCHLEVEL"" is now ""PERL_VERSION""" 4 .el .IP "\f(CWPATCHLEVEL\fR is now \f(CWPERL_VERSION\fR" 4 .IX Item "PATCHLEVEL is now PERL_VERSION" The cpp macros \f(CW\*(C`PERL_REVISION\*(C'\fR, \f(CW\*(C`PERL_VERSION\*(C'\fR, and \f(CW\*(C`PERL_SUBVERSION\*(C'\fR are now available by default from perl.h, and reflect the base revision, patchlevel, and subversion respectively. \f(CW\*(C`PERL_REVISION\*(C'\fR had no prior equivalent, while \f(CW\*(C`PERL_VERSION\*(C'\fR and \f(CW\*(C`PERL_SUBVERSION\*(C'\fR were previously available as \f(CW\*(C`PATCHLEVEL\*(C'\fR and \f(CW\*(C`SUBVERSION\*(C'\fR. .Sp The new names cause less pollution of the \fBcpp\fR namespace and reflect what the numbers have come to stand for in common practice. For compatibility, the old names are still supported when \fIpatchlevel.h\fR is explicitly included (as required before), so there is no source incompatibility from the change. .SS "Binary Incompatibilities" .IX Subsection "Binary Incompatibilities" In general, the default build of this release is expected to be binary compatible for extensions built with the 5.005 release or its maintenance versions. However, specific platforms may have broken binary compatibility due to changes in the defaults used in hints files. Therefore, please be sure to always check the platform-specific \s-1README\s0 files for any notes to the contrary. .PP The usethreads or usemultiplicity builds are \fBnot\fR binary compatible with the corresponding builds in 5.005. .PP On platforms that require an explicit list of exports (\s-1AIX\s0, \s-1OS/2\s0 and Windows, among others), purely internal symbols such as parser functions and the run time opcodes are not exported by default. Perl 5.005 used to export all functions irrespective of whether they were considered part of the public \s-1API\s0 or not. .PP For the full list of public \s-1API\s0 functions, see perlapi. .SH "Known Problems" .IX Header "Known Problems" .SS "Localizing a tied hash element may leak memory" .IX Subsection "Localizing a tied hash element may leak memory" As of the 5.6.1 release, there is a known leak when code such as this is executed: .PP .Vb 2 \& use Tie::Hash; \& tie my %tie_hash => \*(AqTie::StdHash\*(Aq; \& \& ... \& \& local($tie_hash{Foo}) = 1; # leaks .Ve .SS "Known test failures" .IX Subsection "Known test failures" .IP "\(bu" 4 64\-bit builds .Sp Subtest #15 of lib/b.t may fail under 64\-bit builds on platforms such as HP-UX \s-1PA64\s0 and Linux \s-1IA64\s0. The issue is still being investigated. .Sp The lib/io_multihomed test may hang in HP-UX if Perl has been configured to be 64\-bit. Because other 64\-bit platforms do not hang in this test, HP-UX is suspect. All other tests pass in 64\-bit HP-UX. The test attempts to create and connect to \&\*(L"multihomed\*(R" sockets (sockets which have multiple \s-1IP\s0 addresses). .Sp Note that 64\-bit support is still experimental. .IP "\(bu" 4 Failure of Thread tests .Sp The subtests 19 and 20 of lib/thr5005.t test are known to fail due to fundamental problems in the 5.005 threading implementation. These are not new failures\*(--Perl 5.005_0x has the same bugs, but didn't have these tests. (Note that support for 5.005\-style threading remains experimental.) .IP "\(bu" 4 \&\s-1NEXTSTEP\s0 3.3 \s-1POSIX\s0 test failure .Sp In \s-1NEXTSTEP\s0 3.3p2 the implementation of the \fIstrftime\fR\|(3) in the operating system libraries is buggy: the \f(CW%j\fR format numbers the days of a month starting from zero, which, while being logical to programmers, will cause the subtests 19 to 27 of the lib/posix test may fail. .IP "\(bu" 4 Tru64 (aka Digital \s-1UNIX\s0, aka \s-1DEC\s0 \s-1OSF/1\s0) lib/sdbm test failure with gcc .Sp If compiled with gcc 2.95 the lib/sdbm test will fail (dump core). The cure is to use the vendor cc, it comes with the operating system and produces good code. .SS "\s-1EBCDIC\s0 platforms not fully supported" .IX Subsection "EBCDIC platforms not fully supported" In earlier releases of Perl, \s-1EBCDIC\s0 environments like \s-1OS390\s0 (also known as Open Edition \s-1MVS\s0) and VM-ESA were supported. Due to changes required by the \s-1UTF\-8\s0 (Unicode) support, the \s-1EBCDIC\s0 platforms are not supported in Perl 5.6.0. .PP The 5.6.1 release improves support for \s-1EBCDIC\s0 platforms, but they are not fully supported yet. .SS "UNICOS/mk \s-1CC\s0 failures during Configure run" .IX Subsection "UNICOS/mk CC failures during Configure run" In UNICOS/mk the following errors may appear during the Configure run: .PP .Vb 6 \& Guessing which symbols your C compiler and preprocessor define... \& CC\-20 cc: ERROR File = try.c, Line = 3 \& ... \& bad switch yylook 79bad switch yylook 79bad switch yylook 79bad switch yylook 79#ifdef A29K \& ... \& 4 errors detected in the compilation of "try.c". .Ve .PP The culprit is the broken awk of UNICOS/mk. The effect is fortunately rather mild: Perl itself is not adversely affected by the error, only the h2ph utility coming with Perl, and that is rather rarely needed these days. .SS "Arrow operator and arrays" .IX Subsection "Arrow operator and arrays" When the left argument to the arrow operator \f(CW\*(C`\->\*(C'\fR is an array, or the \f(CW\*(C`scalar\*(C'\fR operator operating on an array, the result of the operation must be considered erroneous. For example: .PP .Vb 2 \& @x\->[2] \& scalar(@x)\->[2] .Ve .PP These expressions will get run-time errors in some future release of Perl. .SS "Experimental features" .IX Subsection "Experimental features" As discussed above, many features are still experimental. Interfaces and implementation of these features are subject to change, and in extreme cases, even subject to removal in some future release of Perl. These features include the following: .IP "Threads" 4 .IX Item "Threads" .PD 0 .IP "Unicode" 4 .IX Item "Unicode" .IP "64\-bit support" 4 .IX Item "64-bit support" .IP "Lvalue subroutines" 4 .IX Item "Lvalue subroutines" .IP "Weak references" 4 .IX Item "Weak references" .IP "The pseudo-hash data type" 4 .IX Item "The pseudo-hash data type" .IP "The Compiler suite" 4 .IX Item "The Compiler suite" .IP "Internal implementation of file globbing" 4 .IX Item "Internal implementation of file globbing" .IP "The \s-1DB\s0 module" 4 .IX Item "The DB module" .IP "The regular expression code constructs:" 4 .IX Item "The regular expression code constructs:" .PD \&\f(CW\*(C`(?{ code })\*(C'\fR and \f(CW\*(C`(??{ code })\*(C'\fR .SH "Obsolete Diagnostics" .IX Header "Obsolete Diagnostics" .IP "Character class syntax [: :] is reserved for future extensions" 4 .IX Item "Character class syntax [: :] is reserved for future extensions" (W) Within regular expression character classes ([]) the syntax beginning with \*(L"[:\*(R" and ending with \*(L":]\*(R" is reserved for future extensions. If you need to represent those character sequences inside a regular expression character class, just quote the square brackets with the backslash: \*(L"\e[:\*(R" and \*(L":\e]\*(R". .IP "Ill-formed logical name |%s| in prime_env_iter" 4 .IX Item "Ill-formed logical name |%s| in prime_env_iter" (W) A warning peculiar to \s-1VMS\s0. A logical name was encountered when preparing to iterate over \f(CW%ENV\fR which violates the syntactic rules governing logical names. Because it cannot be translated normally, it is skipped, and will not appear in \f(CW%ENV\fR. This may be a benign occurrence, as some software packages might directly modify logical name tables and introduce nonstandard names, or it may indicate that a logical name table has been corrupted. .IP "In string, @%s now must be written as \e@%s" 4 .IX Item "In string, @%s now must be written as @%s" The description of this error used to say: .Sp .Vb 2 \& (Someday it will simply assume that an unbackslashed @ \& interpolates an array.) .Ve .Sp That day has come, and this fatal error has been removed. It has been replaced by a non-fatal warning instead. See \*(L"Arrays now always interpolate into double-quoted strings\*(R" for details. .ie n .IP "Probable precedence problem on %s" 4 .el .IP "Probable precedence problem on \f(CW%s\fR" 4 .IX Item "Probable precedence problem on %s" (W) The compiler found a bareword where it expected a conditional, which often indicates that an || or && was parsed as part of the last argument of the previous construct, for example: .Sp .Vb 1 \& open FOO || die; .Ve .IP "regexp too big" 4 .IX Item "regexp too big" (F) The current implementation of regular expressions uses shorts as address offsets within a string. Unfortunately this means that if the regular expression compiles to longer than 32767, it'll blow up. Usually when you want a regular expression this big, there is a better way to do it with multiple statements. See perlre. .ie n .IP "Use of ""$$<digit>"" to mean ""${$}<digit>"" is deprecated" 4 .el .IP "Use of ``$$<digit>'' to mean ``${$}<digit>'' is deprecated" 4 .IX Item "Use of $$<digit> to mean ${$}<digit> is deprecated" (D) Perl versions before 5.004 misinterpreted any type marker followed by \*(L"$\*(R" and a digit. For example, \*(L"$$0\*(R" was incorrectly taken to mean \&\*(L"${$}0\*(R" instead of \*(L"${$0}\*(R". This bug is (mostly) fixed in Perl 5.004. .Sp However, the developers of Perl 5.004 could not fix this bug completely, because at least two widely-used modules depend on the old meaning of \&\*(L"$$0\*(R" in a string. So Perl 5.004 still interprets \*(L"$$<digit>\*(R" in the old (broken) way inside strings; but it generates this message as a warning. And in Perl 5.005, this special treatment will cease. .SH "Reporting Bugs" .IX Header "Reporting Bugs" If you find what you think is a bug, you might check the articles recently posted to the comp.lang.perl.misc newsgroup. There may also be information at http://www.perl.com/ , the Perl Home Page. .PP If you believe you have an unreported bug, please run the \fBperlbug\fR program included with your release. Be sure to trim your bug down to a tiny but sufficient test case. Your bug report, along with the output of \f(CW\*(C`perl \-V\*(C'\fR, will be sent off to perlbug@perl.org to be analysed by the Perl porting team. .SH "SEE ALSO" .IX Header "SEE ALSO" The \fIChanges\fR file for exhaustive details on what changed. .PP The \fI\s-1INSTALL\s0\fR file for how to build Perl. .PP The \fI\s-1README\s0\fR file for general stuff. .PP The \fIArtistic\fR and \fICopying\fR files for copyright information. .SH "HISTORY" .IX Header "HISTORY" Written by Gurusamy Sarathy <\fIgsar@ActiveState.com\fR>, with many contributions from The Perl Porters. .PP Send omissions or corrections to <\fIperlbug@perl.org\fR>.