# phpman > perldoc > Moose::Cookbook::Meta::WhyMeta

## NAME
    [Moose::Cookbook::Meta::WhyMeta](https://www.chedong.com/phpMan.php/perldoc/Moose%3A%3ACookbook%3A%3AMeta%3A%3AWhyMeta/markdown) - Welcome to the meta world (Why Go Meta?)

## VERSION
    version 2.2200

## SUMMARY
    You might want to read [Moose::Manual::MOP](https://www.chedong.com/phpMan.php/perldoc/Moose%3A%3AManual%3A%3AMOP/markdown) 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](https://www.chedong.com/phpMan.php/perldoc/Moose%3A%3AMeta%3A%3AClass/markdown), [Moose::Meta::Attribute](https://www.chedong.com/phpMan.php/perldoc/Moose%3A%3AMeta%3A%3AAttribute/markdown), 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](https://www.chedong.com/phpMan.php/perldoc/My%3A%3AClass/markdown)->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](https://www.chedong.com/phpMan.php/perldoc/My%3A%3AClass/markdown)->meta()->table_name()".

## SEE ALSO
    Many of the MooseX modules on CPAN implement metaclass extensions. A couple good examples
    include [MooseX::Aliases](https://www.chedong.com/phpMan.php/perldoc/MooseX%3A%3AAliases/markdown) and [MooseX::UndefTolerant](https://www.chedong.com/phpMan.php/perldoc/MooseX%3A%3AUndefTolerant/markdown). For a more complex example see [Fey::ORM](https://www.chedong.com/phpMan.php/perldoc/Fey%3A%3AORM/markdown) or
    [Bread::Board::Declare](https://www.chedong.com/phpMan.php/perldoc/Bread%3A%3ABoard%3A%3ADeclare/markdown).

## AUTHORS
    *   Stevan Little <<stevan@cpan.org>>

    *   Dave Rolsky <<autarch@urth.org>>

    *   Jesse Luehrs <<doy@cpan.org>>

    *   Shawn M Moore <<sartak@cpan.org>>

    *   יובל קוג'מן (Yuval Kogman) <<nothingmuch@woobling.org>>

    *   Karen Etheridge <<ether@cpan.org>>

    *   Florian Ragwitz <<rafl@debian.org>>

    *   Hans Dieter Pearcey <<hdp@cpan.org>>

    *   Chris Prather <<chris@prather.org>>

    *   Matt S Trout <<mstrout@cpan.org>>

## 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.