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File::Find::Rule::Extending - the mini-guide to extending File::Find::Rule
Contents
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.
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.
Declareyourpackage
package File::Find::Rule::Random;
use strict;
InheritmethodsfromFile::Find::Rule
# take useful things from File::Find::Rule
use base 'File::Find::Rule';
Forceyourmadnessintothemainpackage
# 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.
Takingnoarguments.
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.
Name
File::Find::Rule::Extending - the mini-guide to extending File::Find::Rule
See Also
File::Find::Rule
File::Find::Rule::MMagic was the first extension module, so maybe check that out.
perl v5.40.1 2025-06-05 File::Find::Rule::Extending(3pm)
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;
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