| Moose::Cookbook::Meta::WhyMeta(3pm) - phpMan
Moose::Cookbook::Meta::WhyMeta(User Contributed Perl DocumentaMoose::Cookbook::Meta::WhyMeta(3pm)
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 AT iinteractive.com>
· Dave Rolsky <autarch AT urth.org>
· Jesse Luehrs <doy AT tozt.net>
· Shawn M Moore <code AT sartak.org>
· XXXX XXX'XX (Yuval Kogman) <nothingmuch AT woobling.org>
· Karen Etheridge <ether AT cpan.org>
· Florian Ragwitz <rafl AT debian.org>
· Hans Dieter Pearcey <hdp AT weftsoar.net>
· Chris Prather <chris AT prather.org>
· Matt S Trout <mst AT shadowcat.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.
perl v5.20.1 2014-09-25 Moose::Cookbook::Meta::WhyMeta(3pm)
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