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


NAME

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

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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;

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DESCRIPTION

the File::Find::Object::Rule manpage inherits the File::Find::Rule manpage'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';
 
=head3 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.

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NOTES ABOUT THE CALLBACK

The callback can access the the File::Find::Object::Result manpage using $self->finder->item_obj().

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AUTHOR

Richard Clamp <richardc@unixbeard.net>

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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.

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SEE ALSO

the File::Find::Object::Rule manpage

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

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