MooseX::Traits(3) Automatically apply roles at object creation time


version 0.13


Given some roles:

package Role;
use Moose::Role;
has foo => ( is => 'ro', isa => 'Int' required => 1 );

And a class:

  package Class;
  use Moose;
  with 'MooseX::Traits';

Apply the roles to the class at "new" time:

  my $class = Class->with_traits('Role')->new( foo => 42 );

Then use your customized class:

  $class->isa('Class'); # true
  $class->does('Role'); # true
  $class->foo; # 42


Often you want to create components that can be added to a class arbitrarily. This module makes it easy for the end user to use these components. Instead of requiring the user to create a named class with the desired roles applied, or apply roles to the instance one-by-one, he can just create a new class from yours with "with_traits", and then instantiate that.

There is also "new_with_traits", which exists for compatibility reasons. It accepts a "traits" parameter, creates a new class with those traits, and then instantiates it.

   Class->new_with_traits( traits => [qw/Foo Bar/], foo => 42, bar => 1 )

returns exactly the same object as

   Class->with_traits(qw/Foo Bar/)->new( foo => 42, bar => 1 )

would. But you can also store the result of "with_traits", and call other methods:

   my $c = Class->with_traits(qw/Foo Bar/);
   $c->new( foo => 42 );
   $c->whatever( foo => 1234 );

And so on.


$class->with_traits( @traits )
Return a new class with the traits applied. Use like:
$class->new_with_traits(%args, traits => \@traits)
"new_with_traits" can also take a hashref, e.g.:

  my $instance = $class->new_with_traits({ traits => \@traits, foo => 'bar' });


This role will add the following attributes to the consuming class.


You can override the value of this attribute with "default" to automatically prepend a namespace to the supplied traits. (This can be overridden by prefixing the trait name with "+".)


  package Another::Trait;
  use Moose::Role;
  has 'bar' => (
      is       => 'ro',
      isa      => 'Str',
      required => 1,
  package Another::Class;
  use Moose;
  with 'MooseX::Traits';
  has '+_trait_namespace' => ( default => 'Another' );
  my $instance = Another::Class->new_with_traits(
      traits => ['Trait'], # "Another::Trait", not "Trait"
      bar    => 'bar',
  $instance->does('Trait')          # false
  $instance->does('Another::Trait') # true
  my $instance2 = Another::Class->new_with_traits(
      traits => ['+Trait'], # "Trait", not "Another::Trait"
  $instance2->does('Trait')          # true
  $instance2->does('Another::Trait') # false


Jonathan Rockway <[email protected]>



This software is copyright (c) 2008 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.