Tie::Scalar

Tie::Scalar(3)         Perl Programmers Reference Guide         Tie::Scalar(3)



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 "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.

       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 "tie $scalar, classname". Asso-
           ciates 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 spe-
           cific 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.



perl v5.8.6                       2001-09-21                    Tie::Scalar(3)