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


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



perl v5.8.5                 2002-11-06                          1





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


           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 v5.8.5                 2002-11-06                          2