Tie::Scalar(3perlPerl Programmers Reference GuiTie::Scalar(r)



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::Std-
       Scalar 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, class-
           name". Associates a new scalar instance with the spec-
           ified class. "LIST" would represent additional argu-
           ments (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 ref-
           erenced by this.  This is rarely needed, as Perl man-
           ages 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.



perl v5.6.1                 2001-02-23         Tie::Scalar(r)