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


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 v5.38.0                      2023-07-25    File::Find::Rule::Extending(3)