3 Catalyst::Manual::CatalystAndMoose - How Catalyst 5.8+ and Moose relate
8 Since version 5.8 the core of Catalyst is based on L<Moose>. Although
9 the developers went through great lengths to allow for a seamless
10 transition, there are still a few things to keep in mind when trying
11 to exploit the power of L<Moose> in your Catalyst application.
13 This document provides you with a short overview of common caveats and
14 best practices to use L<Moose>-based classes within Catalyst.
17 =head1 THE CONTEXT CLASS
19 A Moose-ified version of the context class should look like this:
24 use namespace::autoclean;
26 # your roles and plugins
29 $app->config( name => 'MyApp' );
32 # method modifiers must be created after setup because otherwise they will
33 # conflict with plugin overrides
35 after 'finalize' => sub{
37 $c->log->info( 'done!' );
40 You should also be aware, that roles in C<< $c->setup >> are applied
41 after the last plugin with all the benefits of using a single C<<
42 with() >> statement in an ordinary L<Moose> class.
44 Your class is automatically made immutable at the end of the current file.
46 CAVEAT: Using roles in C<< $c->setup >> was implemented in Catalyst
47 version 5.80004. In prior versions you might get away with
49 after 'setup_plugins' => sub{ with(
57 but this is discouraged and you should upgrade to 5.80004 anyway,
58 because it fixes a few important regression against 5.71
60 CAVEAT: Using roles in C<< $c->setup >> will not currently allow
61 you to pass parameters to roles, or perform conflict resolution.
62 Conflict detection still works as expected.
66 Most of the request-specific attributes like C<$c->stash>,
67 C<$c->request> and C<$c->response> have been converted to
68 L<Moose> attributes but without type constraints, attribute helpers or
69 builder methods. This ensures that Catalyst 5.8 is fully backwards
70 compatible to applications using the published API of Catalyst 5.7 but
71 slightly limits the gains that could be had by wielding the full power
72 of L<Moose> attributes.
74 Most of the accessors to information gathered during compile time is
75 managed by C<Catalyst::ClassData>, which is a L<Moose>-aware version
76 of L<Class::Data::Inheritable> but not compatible with
77 L<MooseX::ClassAttribute>.
80 =head2 ROLES AND METHOD MODIFIERS
82 Since the release of Catalyst version 5.8 the only reason for creating
83 a Catalyst extension as a plugin is to provide backward compatibility
84 to applications still using version 5.7.
86 If backward compatibility is of no concern to you, you could as easily
87 rewrite your plugins as roles and enjoy all the benefits of automatic
88 method re-dispatching of C<< before >> and C<< after >> method
89 modifiers, naming conflict detecting and generally cleaner code.
91 Plugins and roles should never use
93 after 'setup' => sub { ... } # wrong
97 after 'setup_finalize' => sub { ... } # this will work
99 to run their own setup code if needed. If they need to influence the
100 setup process itself, they can modify C<< setup_dispatcher() >>,
101 C<< setup_engine()>>, C<< setup_stats() >>, C<< setup_components() >>
102 and C<< setup_actions() >>, but this should be done with due
103 consideration and as late as possible.
107 To activate Catalyst's action attributes, Moose-ified controller
108 classes need to extend L<Catalyst::Controller> at compile time before
109 the actions themselves are declared:
111 package Catalyst::Controller::Root;
113 use namespace::autoclean;
115 BEGIN { extends 'Catalyst::Controller'; }
117 # your controller roles
120 =head2 Controller Roles
122 It is possible to use roles to apply method modifiers on controller actions
123 from 5.80003 onwards, or use modifiers in actions in your controller classes
126 It is possible to have action methods with attributes inside Moose roles, using
127 the trait introduced in L<MooseX::MethodAttributes> version 0.12, example:
129 package MyApp::ControllerRole;
130 use Moose::Role -traits => 'MethodAttributes';
131 use namespace::autoclean;