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File::Find::Rule::Extending(3)       User Contributed Perl Documentation      File::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 everyone 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 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.

   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 v5.16.2                                     2011-09-19                   File::Find::Rule::Extending(3)