Shlomi Fish > File-Find-Object-Rule-0.0302 > File::Find::Object::Rule::Extending

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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.

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