debian man page for file::find::object::rule::extending

File::Find::Object::Rule::Extending(3pm)		User Contributed Perl Documentation		  File::Find::Object::Rule::Extending(3pm)

NAME
       File::Find::Object::Rule::Extending - the mini-guide to extending File::Find::Object::Rule

SYNOPSIS
	   package File::Find::Object::Rule::Random;

	   use strict;
	   use warnings;

	   # take useful things from File::Find::Object::Rule
	   use base 'File::Find::Object::Rule';

	   # and force our crack into the main namespace
	   sub File::Find::Object::Rule::random () {
	       my $self = shift()->_force_object;
	       $self->exec( sub { rand > 0.5 } );
	   }

	   1;

DESCRIPTION
       File::Find::Object::Rule inherits File::Find::Rule's extensibility. It is now possibile to extend it, using the following conventions.

   Declare your package
	   package File::Find::Object::Rule::Random;

	   use strict;
	   use warnings;

   Inherit methods from File::Find::Object::Rule
	   # take useful things from File::Find::Object::Rule
	   use base 'File::Find::Object::Rule';

       Force your madness into the main package

	   # and force our crack into the main namespace
	   sub File::Find::Object::Rule::random () {
	       my $self = shift()->_force_object;
	       $self->exec( sub { rand > 0.5 } );
	   }

       Yes, we're being very cavalier here and defining things into the main File::Find::Object::Rule namespace.  This is due to lack of
       imaginiation on my part - I simply can't find a way for the functional and oo interface to work without doing this or some kind of
       inheritance, and inheritance stops you using two File::Find::Object::Rule::Foo modules together.

       For this reason try and pick distinct names for your extensions.  If this becomes a problem then I may institute a semi-official registry
       of taken names.

   Taking no arguments.
       Note the null prototype on random.  This is a cheat for the procedural interface to know that your sub takes no arguments, and so allows
       this to happen:

	find( random => in => '.' );

       If you hadn't declared "random" with a null prototype it would have consumed "in" as a parameter to it, then got all confused as it doesn't
       know about a '.' rule.

NOTES ABOUT THE CALLBACK
       The callback can access the File::Find::Object::Result using "$self->finder->item_obj()".

AUTHOR
       Richard Clamp <richardc@unixbeard.net>

COPYRIGHT
       Copyright (C) 2002 Richard Clamp.  All Rights Reserved.

       This module is free software; you can redistribute it and/or modify it under the same terms as Perl itself.

SEE ALSO
       File::Find::Object::Rule

       File::Find::::Rule::MMagic was the first extension module for File::Find::Rule, so maybe check that out.

perl v5.14.2							    2012-05-05				  File::Find::Object::Rule::Extending(3pm)