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::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 overload-
ing 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 sec-
tion not only documents these, but has sample code as well:
TIESCALAR classname, LIST
The method invoked by the command "tie $scalar,
classname". Associates a new scalar instance with the
specified 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
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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 refer-
enced 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 destruc-
tion of an instance.
MORE INFORMATION
The perltie section uses a good example of tying scalars by
associating process IDs with priority.
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