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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" Tie::Scalar, Tie::StdScalar \- base class definitions for tied scalars .SH "SYNOPSIS" .IX Header "SYNOPSIS" .Vb 2 \& package NewScalar; \& require Tie::Scalar; \& \& @ISA = qw(Tie::Scalar); \& \& sub FETCH { ... } # Provide a needed method \& sub TIESCALAR { ... } # Overrides inherited method \& \& \& package NewStdScalar; \& require Tie::Scalar; \& \& @ISA = qw(Tie::StdScalar); \& \& # All methods provided by default, so define only what needs be overridden \& sub FETCH { ... } \& \& \& package main; \& \& tie $new_scalar, \*(AqNewScalar\*(Aq; \& tie $new_std_scalar, \*(AqNewStdScalar\*(Aq; .Ve .SH "DESCRIPTION" .IX Header "DESCRIPTION" This module provides some skeletal methods for scalar-tying classes. See perltie for a list of the functions required in tying a scalar to a package. The basic \fBTie::Scalar\fR package provides a \f(CW\*(C`new\*(C'\fR method, as well as methods \f(CW\*(C`TIESCALAR\*(C'\fR, \f(CW\*(C`FETCH\*(C'\fR and \f(CW\*(C`STORE\*(C'\fR. The \fBTie::StdScalar\fR package provides all the methods specified in perltie. It inherits from \&\fBTie::Scalar\fR and causes scalars tied to it to behave exactly like the built-in scalars, allowing for selective overloading of methods. The \f(CW\*(C`new\*(C'\fR method is provided as a means of grandfathering, for classes that forget to provide their own \f(CW\*(C`TIESCALAR\*(C'\fR method. .PP For developers wishing to write their own tied-scalar classes, the methods are summarized below. The perltie section not only documents these, but has sample code as well: .IP "\s-1TIESCALAR\s0 classname, \s-1LIST\s0" 4 .IX Item "TIESCALAR classname, LIST" The method invoked by the command \f(CW\*(C`tie $scalar, classname\*(C'\fR. Associates a new scalar instance with the specified class. \f(CW\*(C`LIST\*(C'\fR would represent additional arguments (along the lines of AnyDBM_File and compatriots) needed to complete the association. .IP "\s-1FETCH\s0 this" 4 .IX Item "FETCH this" Retrieve the value of the tied scalar referenced by \fIthis\fR. .IP "\s-1STORE\s0 this, value" 4 .IX Item "STORE this, value" Store data \fIvalue\fR in the tied scalar referenced by \fIthis\fR. .IP "\s-1DESTROY\s0 this" 4 .IX Item "DESTROY this" Free the storage associated with the tied scalar referenced by \fIthis\fR. This is rarely needed, as Perl manages its memory quite well. But the option exists, should a class wish to perform specific actions upon the destruction of an instance. .SS "Tie::Scalar vs Tie::StdScalar" .IX Subsection "Tie::Scalar vs Tie::StdScalar" \&\f(CW\*(C`Tie::Scalar\*(C'\fR provides all the necessary methods, but one should realize they do not do anything useful. Calling \f(CW\*(C`Tie::Scalar::FETCH\*(C'\fR or \&\f(CW\*(C`Tie::Scalar::STORE\*(C'\fR results in a (trappable) croak. And if you inherit from \f(CW\*(C`Tie::Scalar\*(C'\fR, you \fImust\fR provide either a \f(CW\*(C`new\*(C'\fR or a \&\f(CW\*(C`TIESCALAR\*(C'\fR method. .PP If you are looking for a class that does everything for you you don't define yourself, use the \f(CW\*(C`Tie::StdScalar\*(C'\fR class, not the \&\f(CW\*(C`Tie::Scalar\*(C'\fR one. .SH "MORE INFORMATION" .IX Header "MORE INFORMATION" The perltie section uses a good example of tying scalars by associating process IDs with priority.