CONTENTS

• NAME
• SYNOPSIS
• DESCRIPTION
  • Tie::Scalar vs Tie::StdScalar
• MORE INFORMATION

#NAME

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

#SYNOPSIS

package NewScalar;require Tie::Scalar;@ISA = qw(Tie::Scalar);sub FETCH { ... }# Provide a needed methodsub TIESCALAR { ... }# Overrides inherited methodpackage NewStdScalar;require Tie::Scalar;@ISA = qw(Tie::StdScalar);# All methods provided by default, so define only what needs be overriddensub FETCH { ... }package main;tie $new_scalar, 'NewScalar';tie $new_std_scalar, 'NewStdScalar';

#DESCRIPTION

This module provides some skeletal methods for scalar-tying classes. Seeperltie for a list of the functions required in tying a scalar to a package. The basicTie::Scalar package provides anew method, as well as methodsTIESCALAR,FETCH andSTORE. TheTie::StdScalar package provides all the methods specified inperltie. It inherits fromTie::Scalar and causes scalars tied to it to behave exactly like the built-in scalars, allowing for selective overloading of methods. Thenew method is provided as a means of grandfathering, for classes that forget to provide their ownTIESCALAR method.

For developers wishing to write their own tied-scalar classes, the methods are summarized below. Theperltie section not only documents these, but has sample code as well:

#TIESCALAR classname, LIST

The method invoked by the commandtie $scalar, classname. Associates a new scalar instance with the specified class.LIST would represent additional arguments (along the lines ofAnyDBM_File and compatriots) needed to complete the association.

#FETCH this

Retrieve the value of the tied scalar referenced bythis.

#STORE this, value

Store datavalue in the tied scalar referenced bythis.

#DESTROY this

Free the storage associated with the tied scalar referenced bythis. 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.

#Tie::Scalar vs Tie::StdScalar

Tie::Scalar provides all the necessary methods, but one should realize they do not do anything useful. CallingTie::Scalar::FETCH orTie::Scalar::STORE results in a (trappable) croak. And if you inherit fromTie::Scalar, youmust provide either anew or aTIESCALAR method.

If you are looking for a class that does everything for you you don't define yourself, use theTie::StdScalar class, not theTie::Scalar one.

#MORE INFORMATION

Theperltie section uses a good example of tying scalars by associating process IDs with priority.

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