NAME¶
Moose::Cookbook::Meta::WhyMeta - Welcome to the meta world (Why Go Meta?)
VERSION¶
version 2.1213
SUMMARY¶
You might want to read Moose::Manual::MOP if you haven't done so yet.
If you've ever thought "Moose is great, but I wish it did X
differently", then you've gone meta. The meta recipes demonstrate how to
change and extend the way Moose works by extending and overriding how the meta
classes (Moose::Meta::Class, Moose::Meta::Attribute, etc) work.
The metaclass API is a set of classes that describe classes, roles, attributes,
etc. The metaclass API lets you ask questions about a class, like "what
attributes does it have?", or "what roles does the class do?"
The metaclass system also lets you make changes to a class, for example by
adding new methods or attributes.
The interface presented by Moose.pm ("has", "with",
"extends") is just a thin layer of syntactic sugar over the
underlying metaclass system.
By extending and changing how this metaclass system works, you can create your
own Moose variant.
Examples¶
Let's say that you want to add additional properties to attributes.
Specifically, we want to add a "label" property to each attribute,
so we can write
"My::Class->meta()->get_attribute('size')->label()". The
first recipe shows how to do this using an attribute trait.
You might also want to add additional properties to your metaclass. For example,
if you were writing an ORM based on Moose, you could associate a table name
with each class via the class's metaclass object, letting you write
"My::Class->meta()->table_name()".
SEE ALSO¶
Many of the MooseX modules on CPAN implement metaclass extensions. A couple good
examples include MooseX::Aliases and MooseX::UndefTolerant. For a more complex
example see Fey::ORM or Bread::Board::Declare.
AUTHORS¶
- •
- Stevan Little <stevan.little@iinteractive.com>
- •
- Dave Rolsky <autarch@urth.org>
- •
- Jesse Luehrs <doy@tozt.net>
- •
- Shawn M Moore <code@sartak.org>
- •
- XXXX XXX'XX (Yuval Kogman) <nothingmuch@woobling.org>
- •
- Karen Etheridge <ether@cpan.org>
- •
- Florian Ragwitz <rafl@debian.org>
- •
- Hans Dieter Pearcey <hdp@weftsoar.net>
- •
- Chris Prather <chris@prather.org>
- •
- Matt S Trout <mst@shadowcat.co.uk>
COPYRIGHT AND LICENSE¶
This software is copyright (c) 2006 by Infinity Interactive, Inc..
This is free software; you can redistribute it and/or modify it under the same
terms as the Perl 5 programming language system itself.