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

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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 Tie::Scalar package provides a new method, as well as methods TIESCALAR, FETCH and STORE. The Tie::StdScalar package provides all the methods specified in perltie. It inherits from Tie::Scalar and causes scalars tied to it to behave exactly like the built-in scalars, allowing for selective overloading of methods. The new method is provided as a means of grandfathering, for classes that forget to provide their own TIESCALAR method.

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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:

TIESCALAR classname, LIST: perldoc2tree.cgi: /usr/lib/perl5/5.8.8/Tie/Scalar.pm: cannot resolve L in paragraph 19.
The method invoked by the command tie $scalar, classname. Associates a new scalar instance with the specified class. LIST would represent additional arguments (along the lines of AnyDBM_File and compatriots) needed to complete 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 the option exists, should a class wish to perform specific actions upon the destruction of an instance.

MORE INFORMATION

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The perltie section uses a good example of tying scalars by associating process IDs with priority.