parent(3) - Linux man page

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';

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.

use Foo;
use parent 'Foo';

History

This module was forked from base to remove the cruft that had accumulated in it.

Caveats

Authors And Contributors

Rafaeel Garcia-Suarez, Bart Lateur, Max Maischein, Anno Siegel, Michael Schwern

Maintainer

Max Maischein " corion@cpan.org "

License

This module is released under the same terms as Perl itself.