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=head1 NAME
File::Find::Rule::Extending - the mini-guide to extending File::Find::Rule
=head1 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;
=head1 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.
=head2 Declare your package
package File::Find::Rule::Random;
use strict;
=head2 Inherit methods from File::Find::Rule
# take useful things from File::Find::Rule
use base 'File::Find::Rule';
=head3 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.
=head2 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 C<random> with a null prototype it would have
consumed C<in> as a parameter to it, then got all confused as it
doesn't know about a C<'.'> rule.
=head1 AUTHOR
Richard Clamp <richardc@unixbeard.net>
=head1 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.
=head1 SEE ALSO
L<File::Find::Rule>
L<File::Find::Rule::MMagic> was the first extension module, so maybe
check that out.
=cut
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