File::Find::Object::Rule::Extending - the mini-guide to extending File::Find::Object::Rule
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;
File::Find::Object::Rule inherits File::Find::Rule's extensibility. It is now possibile to extend it, using the following conventions.
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 } ); }
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.
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.
random
in
'.'
The callback can access the File::Find::Object::Result using $self->finder->item_obj().
$self->finder->item_obj()
Richard Clamp <richardc@unixbeard.net>
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.
File::Find::Object::Rule
File::Find::::Rule::MMagic was the first extension module for File::Find::Rule, so maybe check that out.
To install File::Find::Object::Rule, copy and paste the appropriate command in to your terminal.
cpanm
cpanm File::Find::Object::Rule
CPAN shell
perl -MCPAN -e shell install File::Find::Object::Rule
For more information on module installation, please visit the detailed CPAN module installation guide.