parent - Establish an ISA relationship with base classes at compile time
    package Baz;
    use parent qw(Foo Bar);
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';
This module was forked from base to remove the cruft that had accumulated in it.
Rafaël Garcia-Suarez, Bart Lateur, Max Maischein, Anno Siegel, Michael Schwern
Max Maischein  corion@cpan.org 
Copyright (c) 2007-2017 Max Maischein <corion@cpan.org> Based on the idea of base.pm, which was introduced with Perl 5.004_04.
This module is released under the same terms as Perl itself.