Moose::Cookbook::Snack::Keywords - Restricted "keywords" in Moose

version 2.0010

Moose exports a number of sugar functions in order to emulate Perl built-in keywords. These can cause clashes with other user-defined functions. This document provides a list of those keywords for easy reference.

use Moose adds a method called meta to your class. If this conflicts with a method or function you are using, you can rename it, or prevent it from being installed entirely. To do this, pass the -meta_name option when you use Moose. For instance:

  # install it under a different name
  use Moose -meta_name => 'moose_meta';

  # don't install it at all
  use Moose -meta_name => undef;

If you are using Moose or Moose::Role its best to avoid these keywords:

extends

with

has

before

after

around

super

override

inner

augment

confess

blessed

If you are using Moose::Util::TypeConstraints its best to avoid these keywords

type

subtype

class_type

role_type

maybe_type

duck_type

as

where

message

optimize_as

inline_as

coerce

from

via

enum

find_type_constraint

register_type_constraint

To remove the sugar functions Moose exports just add no Moose at the bottom of your code:

  package Thing;
  use Moose;

  # code here

  no Moose;

This will unexport the sugar functions that Moose originally exported. The same will also work for Moose::Role and Moose::Util::TypeConstraints.

Moose, Moose::Role and Moose::Util::TypeConstraints all use Sub::Exporter to handle all their exporting needs. This means that all the features that Sub::Exporter provides are also available to them.

For instance, with Sub::Exporter you can rename keywords, like so:

  package LOL::Cat;
  use Moose 'has' => { -as => 'i_can_haz' };

  i_can_haz 'cheeseburger' => (
      is      => 'rw',
      trigger => sub { print "NOM NOM" }
  );

  LOL::Cat->new->cheeseburger('KTHNXBYE');

See the Sub::Exporter docs for more information.

You can also use namespace::autoclean to clean up your namespace. This will remove all imported functions from your namespace. Note that if you are importing functions that are intended to be used as methods (this includes overload, due to internal implementation details), it will remove these as well.

Another option is to use namespace::clean directly, but you must be careful not to remove meta when doing so:

  package Foo;
  use Moose;
  use namespace::clean -except => 'meta';
  # ...

Moose

Moose::Role

Moose::Utils::TypeConstraints

Sub::Exporter

namespace::autoclean

namespace::clean

Stevan Little <stevan@iinteractive.com>

This software is copyright (c) 2011 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.