File::Find::Rule::Extending

File::Find::Rule::ExtUsernContributed Perl DocuFile::Find::Rule::Extending(3)



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 every-
       one 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 inheri-
       tance 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 v5.8.8			  2006-06-01   File::Find::Rule::Extending(3)