The London Perl and Raku Workshop takes place on 26th Oct 2024. If your company depends on Perl, please consider sponsoring and/or attending.


Moose::Util - Utilities for working with Moose classes


version 2.0604


  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_or_obj)

Returns true if $class_or_obj does the given $role_or_obj. The role can be provided as a name or a Moose::Meta::Role object.

The class must already have a metaclass for this to work. If it doesn't, this function simply returns false.

search_class_by_role($class_or_obj, $role_or_obj)

Returns the first class in the class's precedence list that does $role_or_obj, if any. The role can be either a name or a Moose::Meta::Role object.

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 a list of names or Moose::Meta::Role objects, 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.

with_traits($class_name, @role_names)

This function creates a new class from $class_name with each of @role_names applied. It returns the name of the new class.

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.

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.


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.


Here is a list of possible functions to write

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


See "BUGS" in Moose for details on reporting bugs.


Moose is maintained by the Moose Cabal, along with the help of many contributors. See "CABAL" in Moose and "CONTRIBUTORS" in Moose for details.


This software is copyright (c) 2012 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.