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Dave Rolsky
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Moose::Util - Utilities for working with Moose classes


  use Moose::Util qw/find_meta does_role search_class_by_role/;

  my $meta = find_meta($object) || die "No metaclass found";

  if (does_role($object, $role)) {
    print "The object can do $role!\n";

  my $class = search_class_by_role($object, 'FooRole');
  print "Nearest class with 'FooRole' is $class\n";


This module provides a set of utility functions. Many of these functions are intended for use in Moose itself or MooseX modules, but some of them may be useful for use in your own code.



This method takes a class name or object and attempts to find a metaclass for the class, if one exists. It will not create one if it does not yet exist.

does_role($class_or_obj, $role_name)

Returns true if $class_or_obj does the given $role_name.

The class must already have a metaclass for this to work.

search_class_by_role($class_or_obj, $role_name)

Returns the first class in the class's precedence list that does $role_name, if any.

The class must already have a metaclass for this to work.

apply_all_roles($applicant, @roles)

This function applies one or more roles to the given $applicant The applicant can be a role name, class name, or object.

The $applicant must already have a metaclass object.

The list of @roles should be a list of names, each of which can be followed by an optional hash reference of options (-excludes and -alias).

ensure_all_roles($applicant, @roles)

This function is similar to "apply_all_roles", but only applies roles that $applicant does not already consume.

get_all_attribute_values($meta, $instance)

Returns a hash reference containing all of the $instance's attributes. The keys are attribute names.

get_all_init_args($meta, $instance)

Returns a hash reference containing all of the init_arg values for the instance's attributes. The values are the associated attribute values. If an attribute does not have a defined init_arg, it is skipped.

This could be useful in cloning an object.

resolve_metaclass_alias($category, $name, %options)
resolve_metatrait_alias($category, $name, %options)

Resolves a short name to a full class name. Short names are often used when specifying the metaclass or traits option for an attribute:

    has foo => (
        metaclass => "Bar",

The name resolution mechanism is covered in "Metaclass and Trait Name Resolution" in Moose.


Given a list of scalars, turns them into a proper list in English ("one and two", "one, two, three, and four"). This is used to help us make nicer error messages.

meta_class_alias($to[, $from])
meta_attribute_alias($to[, $from])

Create an alias from the class $from (or the current package, if $from is unspecified), so that "Metaclass and Trait Name Resolution" in Moose works properly.


Here is a list of possible functions to write

discovering original method from modified method
search for origin class of a method or attribute


All complex software has bugs lurking in it, and this module is no exception. If you find a bug please either email me, or add the bug to cpan-RT.


Anders Nor Berle <debolaz@gmail.com>

with contributions from:

Robert (phaylon) Sedlacek

Stevan Little


Copyright 2007-2009 by Infinity Interactive, Inc.


This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself.