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

- NAME
- SYNOPSIS
- DESCRIPTION
  - Declare your package
  - Inherit methods from File::Find::Object::Rule
    - Force your madness into the main package
  - Taking no arguments.
- NOTES ABOUT THE CALLBACK
- AUTHOR
- COPYRIGHT
- SEE ALSO

# 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.

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