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


    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';


This module provides some skeletal methods for scalar-tying classes. See the perltie manpage 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 the perltie manpage. 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, the methods are summarized below. The the perltie manpage section not only documents these, but has sample code as well:

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 the AnyDBM_File manpage 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.

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.


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