Tie::Scalar, Tie::StdScalar - base class definitions for tied scalars
package NewScalar; require Tie::Scalar; @ISA = qw(Tie::Scalar); sub FETCH { ... } # Provide a needed method sub TIESCALAR { ... } # Overrides inherited method package NewStdScalar; require Tie::Scalar; @ISA = qw(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 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.
new
TIESCALAR
FETCH
STORE
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:
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 AnyDBM_File and compatriots) needed to complete the association.
tie $scalar, classname
LIST
Retrieve the value of the tied scalar referenced by this.
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.
Tie::Scalar provides all the necessary methods, but one should realize they do not do anything useful. Calling Tie::Scalar::FETCH or Tie::Scalar::STORE results in a (trappable) croak. And if you inherit from Tie::Scalar, you must provide either a new or a TIESCALAR method.
Tie::Scalar
Tie::Scalar::FETCH
Tie::Scalar::STORE
If you are looking for a class that does everything for you you don't define yourself, use the Tie::StdScalar class, not the Tie::Scalar one.
Tie::StdScalar
The perltie section uses a good example of tying scalars by associating process IDs with priority.
To install vars, copy and paste the appropriate command in to your terminal.
cpanm
cpanm vars
CPAN shell
perl -MCPAN -e shell install vars
For more information on module installation, please visit the detailed CPAN module installation guide.