MAN page from Old RedHat 5.X perl-5.004-4.i386.rpm

Tie::Scalar

Section: Perl Programmers Reference Guide (3)
Updated: perl 5.004, patch 04
Index

NAME

Tie::Scalar, Tie::StdScalar - base class definitions for tied scalars

SYNOPSIS

    package NewScalar;    require Tie::Scalar;         @ISA = (Tie::Scalar);         sub FETCH { ... }           # Provide a needed method    sub TIESCALAR { ... }       # Overrides inherited method                  package NewStdScalar;    require Tie::Scalar;        @ISA = (Tie::StdScalar);        # All methods provided by default, so define only what needs be overridden    sub FETCH { ... }            package main;        tie $new_scalar, 'NewScalar';    tie $new_std_scalar, 'NewStdScalar';

DESCRIPTION

This module provides some skeletal methods for scalar-tying classes. Seethe perltie manpage for a list of the functions required in tying a scalar to apackage. The basic Tie::Scalar package provides a new method, as wellas methods TIESCALAR, FETCH and STORE. The Tie::StdScalarpackage provides all the methods specified in the perltie manpage. It inherits fromTie::Scalar and causes scalars tied to it to behave exactly like thebuilt-in scalars, allowing for selective overloading of methods. The newmethod is provided as a means of grandfathering, for classes that forget toprovide their own TIESCALAR method.

For developers wishing to write their own tied-scalar classes, the methodsare summarized below. The the perltie manpage section not only documents these, buthas sample code as well:

TIESCALAR classname, LIST: The method invoked by the command tie $scalar, classname. Associates a newscalar instance with the specified class. LIST would represent additionalarguments (along the lines of the AnyDBM_File manpage and compatriots) needed tocomplete the association.
FETCH this: Retrieve the value of the tied scalar referenced by this.
STORE this, value: Store data value in the tied scalar referenced by this.
DESTROY this: Free the storage associated with the tied scalar referenced by this.This is rarely needed, as Perl manages its memory quite well. But theoption exists, should a class wish to perform specific actions upon thedestruction of an instance.

MORE INFORMATION

The the perltie manpage section uses a good example of tying scalars by associatingprocess IDs with priority.

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