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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++. 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Always turn off hyphenation; it makes .\" way too many mistakes in technical documents. .if n .ad l .nh .SH "NAME" autodie \- Replace functions with ones that succeed or die with lexical scope .SH "SYNOPSIS" .IX Header "SYNOPSIS" .Vb 1 \& use autodie; # Recommended: implies \*(Aquse autodie qw(:default)\*(Aq \& \& use autodie qw(:all); # Recommended more: defaults and system/exec. \& \& use autodie qw(open close); # open/close succeed or die \& \& open(my $fh, "<", $filename); # No need to check! \& \& { \& no autodie qw(open); # open failures won\*(Aqt die \& open(my $fh, "<", $filename); # Could fail silently! \& no autodie; # disable all autodies \& } .Ve .SH "DESCRIPTION" .IX Header "DESCRIPTION" .Vb 1 \& bIlujDI\*(Aq yIchegh()Qo\*(Aq; yIHegh()! \& \& It is better to die() than to return() in failure. \& \& \-\- Klingon programming proverb. .Ve .PP The \f(CW\*(C`autodie\*(C'\fR pragma provides a convenient way to replace functions that normally return false on failure with equivalents that throw an exception on failure. .PP The \f(CW\*(C`autodie\*(C'\fR pragma has \fIlexical scope\fR, meaning that functions and subroutines altered with \f(CW\*(C`autodie\*(C'\fR will only change their behaviour until the end of the enclosing block, file, or \f(CW\*(C`eval\*(C'\fR. .PP If \f(CW\*(C`system\*(C'\fR is specified as an argument to \f(CW\*(C`autodie\*(C'\fR, then it uses IPC::System::Simple to do the heavy lifting. See the description of that module for more information. .SH "EXCEPTIONS" .IX Header "EXCEPTIONS" Exceptions produced by the \f(CW\*(C`autodie\*(C'\fR pragma are members of the autodie::exception class. The preferred way to work with these exceptions under Perl 5.10 is as follows: .PP .Vb 1 \& use feature qw(switch); \& \& eval { \& use autodie; \& \& open(my $fh, \*(Aq<\*(Aq, $some_file); \& \& my @records = <$fh>; \& \& # Do things with @records... \& \& close($fh); \& \& }; \& \& given ($@) { \& when (undef) { say "No error"; } \& when (\*(Aqopen\*(Aq) { say "Error from open"; } \& when (\*(Aq:io\*(Aq) { say "Non\-open, IO error."; } \& when (\*(Aq:all\*(Aq) { say "All other autodie errors." } \& default { say "Not an autodie error at all." } \& } .Ve .PP Under Perl 5.8, the \f(CW\*(C`given/when\*(C'\fR structure is not available, so the following structure may be used: .PP .Vb 2 \& eval { \& use autodie; \& \& open(my $fh, \*(Aq<\*(Aq, $some_file); \& \& my @records = <$fh>; \& \& # Do things with @records... \& \& close($fh); \& }; \& \& if ($@ and $@\->isa(\*(Aqautodie::exception\*(Aq)) { \& if ($@\->matches(\*(Aqopen\*(Aq)) { print "Error from open\en"; } \& if ($@\->matches(\*(Aq:io\*(Aq )) { print "Non\-open, IO error."; } \& } elsif ($@) { \& # A non\-autodie exception. \& } .Ve .PP See autodie::exception for further information on interrogating exceptions. .SH "CATEGORIES" .IX Header "CATEGORIES" Autodie uses a simple set of categories to group together similar built-ins. Requesting a category type (starting with a colon) will enable autodie for all built-ins beneath that category. For example, requesting \f(CW\*(C`:file\*(C'\fR will enable autodie for \f(CW\*(C`close\*(C'\fR, \f(CW\*(C`fcntl\*(C'\fR, \&\f(CW\*(C`fileno\*(C'\fR, \f(CW\*(C`open\*(C'\fR and \f(CW\*(C`sysopen\*(C'\fR. .PP The categories are currently: .PP .Vb 10 \& :all \& :default \& :io \& read \& seek \& sysread \& sysseek \& syswrite \& :dbm \& dbmclose \& dbmopen \& :file \& binmode \& close \& fcntl \& fileno \& flock \& ioctl \& open \& sysopen \& truncate \& :filesys \& chdir \& closedir \& opendir \& link \& mkdir \& readlink \& rename \& rmdir \& symlink \& unlink \& :ipc \& pipe \& :msg \& msgctl \& msgget \& msgrcv \& msgsnd \& :semaphore \& semctl \& semget \& semop \& :shm \& shmctl \& shmget \& shmread \& :socket \& accept \& bind \& connect \& getsockopt \& listen \& recv \& send \& setsockopt \& shutdown \& socketpair \& :threads \& fork \& :system \& system \& exec .Ve .PP Note that while the above category system is presently a strict hierarchy, this should not be assumed. .PP A plain \f(CW\*(C`use autodie\*(C'\fR implies \f(CW\*(C`use autodie qw(:default)\*(C'\fR. Note that \&\f(CW\*(C`system\*(C'\fR and \f(CW\*(C`exec\*(C'\fR are not enabled by default. \f(CW\*(C`system\*(C'\fR requires the optional IPC::System::Simple module to be installed, and enabling \&\f(CW\*(C`system\*(C'\fR or \f(CW\*(C`exec\*(C'\fR will invalidate their exotic forms. See \*(L"\s-1BUGS\s0\*(R" below for more details. .PP The syntax: .PP .Vb 1 \& use autodie qw(:1.994); .Ve .PP allows the \f(CW\*(C`:default\*(C'\fR list from a particular version to be used. This provides the convenience of using the default methods, but the surety that no behavorial changes will occur if the \f(CW\*(C`autodie\*(C'\fR module is upgraded. .PP \&\f(CW\*(C`autodie\*(C'\fR can be enabled for all of Perl's built-ins, including \&\f(CW\*(C`system\*(C'\fR and \f(CW\*(C`exec\*(C'\fR with: .PP .Vb 1 \& use autodie qw(:all); .Ve .SH "FUNCTION SPECIFIC NOTES" .IX Header "FUNCTION SPECIFIC NOTES" .SS "flock" .IX Subsection "flock" It is not considered an error for \f(CW\*(C`flock\*(C'\fR to return false if it fails due to an \f(CW\*(C`EWOULDBLOCK\*(C'\fR (or equivalent) condition. This means one can still use the common convention of testing the return value of \&\f(CW\*(C`flock\*(C'\fR when called with the \f(CW\*(C`LOCK_NB\*(C'\fR option: .PP .Vb 1 \& use autodie; \& \& if ( flock($fh, LOCK_EX | LOCK_NB) ) { \& # We have a lock \& } .Ve .PP Autodying \f(CW\*(C`flock\*(C'\fR will generate an exception if \f(CW\*(C`flock\*(C'\fR returns false with any other error. .SS "system/exec" .IX Subsection "system/exec" The \f(CW\*(C`system\*(C'\fR built-in is considered to have failed in the following circumstances: .IP "\(bu" 4 The command does not start. .IP "\(bu" 4 The command is killed by a signal. .IP "\(bu" 4 The command returns a non-zero exit value (but see below). .PP On success, the autodying form of \f(CW\*(C`system\*(C'\fR returns the \fIexit value\fR rather than the contents of \f(CW$?\fR. .PP Additional allowable exit values can be supplied as an optional first argument to autodying \f(CW\*(C`system\*(C'\fR: .PP .Vb 1 \& system( [ 0, 1, 2 ], $cmd, @args); # 0,1,2 are good exit values .Ve .PP \&\f(CW\*(C`autodie\*(C'\fR uses the IPC::System::Simple module to change \f(CW\*(C`system\*(C'\fR. See its documentation for further information. .PP Applying \f(CW\*(C`autodie\*(C'\fR to \f(CW\*(C`system\*(C'\fR or \f(CW\*(C`exec\*(C'\fR causes the exotic forms \f(CW\*(C`system { $cmd } @args \*(C'\fR or \f(CW\*(C`exec { $cmd } @args\*(C'\fR to be considered a syntax error until the end of the lexical scope. If you really need to use the exotic form, you can call \f(CW\*(C`CORE::system\*(C'\fR or \f(CW\*(C`CORE::exec\*(C'\fR instead, or use \f(CW\*(C`no autodie qw(system exec)\*(C'\fR before calling the exotic form. .SH "GOTCHAS" .IX Header "GOTCHAS" Functions called in list context are assumed to have failed if they return an empty list, or a list consisting only of a single undef element. .SH "DIAGNOSTICS" .IX Header "DIAGNOSTICS" .IP ":void cannot be used with lexical scope" 4 .IX Item ":void cannot be used with lexical scope" The \f(CW\*(C`:void\*(C'\fR option is supported in Fatal, but not \&\f(CW\*(C`autodie\*(C'\fR. To workaround this, \f(CW\*(C`autodie\*(C'\fR may be explicitly disabled until the end of the current block with \f(CW\*(C`no autodie\*(C'\fR. To disable autodie for only a single function (eg, open) use \f(CW\*(C`no autodie qw(open)\*(C'\fR. .ie n .IP "No user hints defined for %s" 4 .el .IP "No user hints defined for \f(CW%s\fR" 4 .IX Item "No user hints defined for %s" You've insisted on hints for user-subroutines, either by pre-pending a \f(CW\*(C`!\*(C'\fR to the subroutine name itself, or earlier in the list of arguments to \f(CW\*(C`autodie\*(C'\fR. However the subroutine in question does not have any hints available. .PP See also \*(L"\s-1DIAGNOSTICS\s0\*(R" in Fatal. .SH "BUGS" .IX Header "BUGS" \&\*(L"Used only once\*(R" warnings can be generated when \f(CW\*(C`autodie\*(C'\fR or \f(CW\*(C`Fatal\*(C'\fR is used with package filehandles (eg, \f(CW\*(C`FILE\*(C'\fR). Scalar filehandles are strongly recommended instead. .PP When using \f(CW\*(C`autodie\*(C'\fR or \f(CW\*(C`Fatal\*(C'\fR with user subroutines, the declaration of those subroutines must appear before the first use of \&\f(CW\*(C`Fatal\*(C'\fR or \f(CW\*(C`autodie\*(C'\fR, or have been exported from a module. Attempting to use \f(CW\*(C`Fatal\*(C'\fR or \f(CW\*(C`autodie\*(C'\fR on other user subroutines will result in a compile-time error. .PP Due to a bug in Perl, \f(CW\*(C`autodie\*(C'\fR may \*(L"lose\*(R" any format which has the same name as an autodying built-in or function. .PP \&\f(CW\*(C`autodie\*(C'\fR may not work correctly if used inside a file with a name that looks like a string eval, such as \fIeval (3)\fR. .SS "autodie and string eval" .IX Subsection "autodie and string eval" Due to the current implementation of \f(CW\*(C`autodie\*(C'\fR, unexpected results may be seen when used near or with the string version of eval. \&\fINone of these bugs exist when using block eval\fR. .PP Under Perl 5.8 only, \f(CW\*(C`autodie\*(C'\fR \fIdoes not\fR propagate into string \f(CW\*(C`eval\*(C'\fR statements, although it can be explicitly enabled inside a string \&\f(CW\*(C`eval\*(C'\fR. .PP Under Perl 5.10 only, using a string eval when \f(CW\*(C`autodie\*(C'\fR is in effect can cause the autodie behaviour to leak into the surrounding scope. This can be worked around by using a \f(CW\*(C`no autodie\*(C'\fR at the end of the scope to explicitly remove autodie's effects, or by avoiding the use of string eval. .PP \&\fINone of these bugs exist when using block eval\fR. The use of \&\f(CW\*(C`autodie\*(C'\fR with block eval is considered good practice. .SS "\s-1REPORTING\s0 \s-1BUGS\s0" .IX Subsection "REPORTING BUGS" Please report bugs via the \s-1CPAN\s0 Request Tracker at <http://rt.cpan.org/NoAuth/Bugs.html?Dist=autodie>. .SH "FEEDBACK" .IX Header "FEEDBACK" If you find this module useful, please consider rating it on the \&\s-1CPAN\s0 Ratings service at <http://cpanratings.perl.org/rate?distribution=autodie> . .PP The module author loves to hear how \f(CW\*(C`autodie\*(C'\fR has made your life better (or worse). Feedback can be sent to <pjf@perltraining.com.au>. .SH "AUTHOR" .IX Header "AUTHOR" Copyright 2008\-2009, Paul Fenwick <pjf@perltraining.com.au> .SH "LICENSE" .IX Header "LICENSE" This module is free software. You may distribute it under the same terms as Perl itself. .SH "SEE ALSO" .IX Header "SEE ALSO" Fatal, autodie::exception, autodie::hints, IPC::System::Simple .PP \&\fIPerl tips, autodie\fR at http://perltraining.com.au/tips/2008\-08\-20.html <http://perltraining.com.au/tips/2008-08-20.html> .SH "ACKNOWLEDGEMENTS" .IX Header "ACKNOWLEDGEMENTS" Mark Reed and Roland Giersig \*(-- Klingon translators. .PP See the \fI\s-1AUTHORS\s0\fR file for full credits. The latest version of this file can be found at <http://github.com/pfenwick/autodie/tree/master/AUTHORS> .