base(3pm) Perl Programmers Reference Guide base(3pm)NAME
base - Establish IS-A relationship with base class at compile time
SYNOPSIS
package Baz;
use base qw(Foo Bar);
DESCRIPTION
Roughly similar in effect to
BEGIN {
require Foo;
require Bar;
push @ISA, qw(Foo Bar);
}
Will also initialize the %FIELDS hash if one of the base classes has it. Multiple inheritance of %FIELDS is not supported. The 'base'
pragma will croak if multiple base classes have a %FIELDS hash. See fields for a description of this feature.
When strict 'vars' is in scope base also let you assign to @ISA without having to declare @ISA with the 'vars' pragma first.
If any of the base classes are not loaded yet, base silently "require"s them. Whether to "require" a base class package is determined by
the absence of a global $VERSION in the base package. If $VERSION is not detected even after loading it, <base> will define $VERSION in
the base package, setting it to the string "-1, set by base.pm".
HISTORY
This module was introduced with Perl 5.004_04.
SEE ALSO
fields
perl v5.8.0 2002-06-01 base(3pm)
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parent(3pm) Perl Programmers Reference Guide parent(3pm)NAME
parent - Establish an ISA relationship with base classes at compile time
SYNOPSIS
package Baz;
use parent qw(Foo Bar);
DESCRIPTION
Allows you to both load one or more modules, while setting up inheritance from those modules at the same time. Mostly similar in effect to
package Baz;
BEGIN {
require Foo;
require Bar;
push @ISA, qw(Foo Bar);
}
By default, every base class needs to live in a file of its own. If you want to have a subclass and its parent class in the same file, you
can tell "parent" not to load any modules by using the "-norequire" switch:
package Foo;
sub exclaim { "I CAN HAS PERL" }
package DoesNotLoadFooBar;
use parent -norequire, 'Foo', 'Bar';
# will not go looking for Foo.pm or Bar.pm
This is equivalent to the following code:
package Foo;
sub exclaim { "I CAN HAS PERL" }
package DoesNotLoadFooBar;
push @DoesNotLoadFooBar::ISA, 'Foo', 'Bar';
This is also helpful for the case where a package lives within a differently named file:
package MyHash;
use Tie::Hash;
use parent -norequire, 'Tie::StdHash';
This is equivalent to the following code:
package MyHash;
require Tie::Hash;
push @ISA, 'Tie::StdHash';
If you want to load a subclass from a file that "require" would not consider an eligible filename (that is, it does not end in either ".pm"
or ".pmc"), use the following code:
package MySecondPlugin;
require './plugins/custom.plugin'; # contains Plugin::Custom
use parent -norequire, 'Plugin::Custom';
DIAGNOSTICS
Class 'Foo' tried to inherit from itself
Attempting to inherit from yourself generates a warning.
package Foo;
use parent 'Foo';
HISTORY
This module was forked from base to remove the cruft that had accumulated in it.
CAVEATS SEE ALSO
base
AUTHORS AND CONTRIBUTORS
Rafaeel Garcia-Suarez, Bart Lateur, Max Maischein, Anno Siegel, Michael Schwern
MAINTAINER
Max Maischein " corion@cpan.org "
Copyright (c) 2007-10 Max Maischein "<corion@cpan.org>" Based on the idea of "base.pm", which was introduced with Perl 5.004_04.
LICENSE
This module is released under the same terms as Perl itself.
perl v5.18.2 2014-01-06 parent(3pm)