Blame lib/File/Find/Object/Rule/Extending.pod

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=head1 NAME
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File::Find::Object::Rule::Extending - the mini-guide to extending File::Find::Object::Rule
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=head1 SYNOPSIS
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    package File::Find::Object::Rule::Random;
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    use strict;
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    use warnings;
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    # take useful things from File::Find::Object::Rule
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    use base 'File::Find::Object::Rule';
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    # and force our crack into the main namespace
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    sub File::Find::Object::Rule::random () {
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        my $self = shift()->_force_object;
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        $self->exec( sub { rand > 0.5 } );
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    }
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    1;
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=head1 DESCRIPTION
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L<File::Find::Object::Rule> inherits L<File::Find::Rule>'s extensibility. It
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is now possibile to extend it, using the following conventions.
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=head2 Declare your package
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    package File::Find::Object::Rule::Random;
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    use strict;
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    use warnings;
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=head2 Inherit methods from File::Find::Object::Rule
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    # take useful things from File::Find::Object::Rule
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    use base 'File::Find::Object::Rule';
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=head3 Force your madness into the main package
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    # and force our crack into the main namespace
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    sub File::Find::Object::Rule::random () {
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        my $self = shift()->_force_object;
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        $self->exec( sub { rand > 0.5 } );
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    }
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Yes, we're being very cavalier here and defining things into the main
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File::Find::Object::Rule namespace.  This is due to lack of imaginiation on my
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part - I simply can't find a way for the functional and oo interface
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to work without doing this or some kind of inheritance, and
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inheritance stops you using two File::Find::Object::Rule::Foo modules
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together.
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For this reason try and pick distinct names for your extensions.  If
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this becomes a problem then I may institute a semi-official registry
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of taken names.
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=head2 Taking no arguments.
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Note the null prototype on random.  This is a cheat for the procedural
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interface to know that your sub takes no arguments, and so allows this
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to happen:
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 find( random => in => '.' );
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If you hadn't declared C<random> with a null prototype it would have
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consumed C<in> as a parameter to it, then got all confused as it
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doesn't know about a C<'.'> rule.
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=head1 NOTES ABOUT THE CALLBACK
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The callback can access the L<File::Find::Object::Result> using
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C<<< $self->finder->item_obj() >>>.
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=head1 AUTHOR
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Richard Clamp <richardc@unixbeard.net>
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=head1 COPYRIGHT
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Copyright (C) 2002 Richard Clamp.  All Rights Reserved.
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This module is free software; you can redistribute it and/or modify it
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under the same terms as Perl itself.
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=head1 SEE ALSO
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L<File::Find::Object::Rule>
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L<File::Find::::Rule::MMagic> was the first extension module for
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L<File::Find::Rule>, so maybe check that out.
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=cut