man Tie::Scalar () - base class definitions for tied scalars

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. See perltie for a list of the functions required in tying a scalar to a package. The basic Tie::Scalar package provides a CWnew method, as well as methods CWTIESCALAR, CWFETCH and CWSTORE. 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 CWnew method is provided as a means of grandfathering, for classes that forget to provide their own CWTIESCALAR method.

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
The method invoked by the command CWtie $scalar, classname. Associates a new scalar instance with the specified class. CWLIST 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

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