7.2.73 Tie::Scalar, Tie::StdScalar - Base Class Definitions for Tied Scalars

package NewScalar; require Tie::Scalar;  @ISA = (Tie::Scalar);  sub FETCH { ... }           # Provides additional method sub TIESCALAR { ... }       # Overrides inherited method  package NewStdScalar; require Tie::Scalar;  @ISA = (Tie::StdScalar);  sub FETCH { ... }  package main;  tie $new_scalar, "NewScalar"; tie $new_std_scalar, "NewStdScalar";

This module provides some skeletal methods for scalar-tying classes. (See Chapter 5 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 methods specified in Chapter 5 . 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.

For developers wishing to write their own tied-scalar classes, methods are summarized below. ( Chapter 5 not only documents these, but also has sample code.)

TIESCALAR ClassName , LIST

The method invoked by the command:

tie $scalar, ClassName, 

LIST

Associates a new scalar instance with the specified class. LIST would represent additional arguments (along the lines of the AnyDBM_File library module and associated modules) needed to complete the association.

FETCH this

Retrieve the value of the tied scalar referenced by this .

STORE this, value

Store 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, since Perl manages its memory well. But the option exists, should a class wish to perform specific actions upon the destruction of an instance.