Tie_Scalar
Tie::Scalar, Tie::StdScalar - base class definitions for tied scalars
<![CDATA[
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;
]]>
This module provides some skeletal methods for scalar-tying classes. See
the perltie manpage
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
the perltie manpage
. 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
the perltie manpage
section 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
arguments (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 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.
The
the perltie manpage
section uses a good example of tying scalars by associating
process IDs with priority.