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

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

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

SYNOPSIS
	package File::Find::Rule::Random;
	use strict;

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

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

	1;

DESCRIPTION
       File::Find::Rule went down so well with the buying public that everyone wanted to add extra features.  With the 0.07 release this became a
       possibility, using the following conventions.

   Declare your package
	package File::Find::Rule::Random;
	use strict;

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

       Force your madness into the main package

	# and force our crack into the main namespace
	sub File::Find::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::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::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.

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::Rule

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

perl v5.12.4							    2011-09-19					  File::Find::Rule::Extending(3pm)