1 package Catalyst::Component;
5 use Class::MOP::Object;
7 use Class::C3::Adopt::NEXT;
8 use Devel::InnerPackage ();
11 use Scalar::Util 'blessed';
12 use namespace::clean -except => 'meta';
14 with 'MooseX::Emulate::Class::Accessor::Fast';
15 with 'Catalyst::ClassData';
20 Catalyst::Component - Catalyst Component Base Class
24 # lib/MyApp/Model/Something.pm
25 package MyApp::Model::Something;
27 use base 'Catalyst::Component';
29 __PACKAGE__->config( foo => 'bar' );
41 my ( $self, $c ) = @_;
42 $c->response->output( $self->foo );
47 # Methods can be a request step
48 $c->forward(qw/MyApp::Model::Something forward_to_me/);
51 print $c->comp('MyApp::Model::Something')->test;
53 print $c->comp('MyApp::Model::Something')->foo;
57 This is the universal base class for Catalyst components
58 (Model/View/Controller).
60 It provides you with a generic new() for component construction through Catalyst's
61 component loader with config() support and a process() method placeholder.
63 B<Note> that calling C<< $self->config >> inside a component is strongly
64 not recommended - the correctly merged config should have already been
65 passed to the constructor and stored in attributes - accessing
66 the config accessor directly from an instance is likely to get the
67 wrong values (as it only holds the class wide config, not things loaded
68 from the config file!)
72 __PACKAGE__->mk_classdata('_plugins');
73 __PACKAGE__->mk_classdata('_config');
75 has catalyst_component_name => ( is => 'ro' ); # Cannot be required => 1 as context
76 # class @ISA component - HATE
77 # Make accessor callable as a class method, as we need to call setup_actions
78 # on the application class, which we don't have an instance of, ewwwww
79 # Also, naughty modules like Catalyst::View::JSON try to write to _everything_,
80 # so spit a warning, ignore that (and try to do the right thing anyway) here..
81 around catalyst_component_name => sub {
82 my ($orig, $self) = (shift, shift);
83 Carp::cluck("Tried to write to the catalyst_component_name accessor - is your component broken or just mad? (Write ignored - using default value.)") if scalar @_;
84 blessed($self) ? $self->$orig() || blessed($self) : $self;
92 $args = $_[0] if ref($_[0]) eq 'HASH';
93 } elsif (@_ == 2) { # is it ($app, $args) or foo => 'bar' ?
95 $args = $_[1] if ref($_[1]) eq 'HASH';
96 } elsif (Class::MOP::is_class_loaded($_[0]) &&
97 $_[0]->isa('Catalyst') && ref($_[1]) eq 'HASH') {
102 } elsif (@_ % 2 == 0) {
106 return $class->merge_config_hashes( $class->config, $args );
110 my ( $class, $c ) = @_;
112 # Temporary fix, some components does not pass context to constructor
113 my $arguments = ( ref( $_[-1] ) eq 'HASH' ) ? $_[-1] : {};
114 if ( my $next = $class->next::can ) {
115 my ($next_package) = Class::MOP::get_code_info($next);
116 warn "There is a COMPONENT method resolving after Catalyst::Component in ${next_package}.\n";
117 warn "This behavior can no longer be supported, and so your application is probably broken.\n";
118 warn "Your linearized isa hierarchy is: " . join(', ', @{ mro::get_linear_isa($class) }) . "\n";
119 warn "Please see perldoc Catalyst::Upgrading for more information about this issue.\n";
121 return $class->new($c, $arguments);
126 # Uncomment once sane to do so
127 #Carp::cluck("config method called on instance") if ref $self;
128 my $config = $self->_config || {};
130 my $newconfig = { %{@_ > 1 ? {@_} : $_[0]} };
132 $self->merge_config_hashes( $config, $newconfig )
135 # this is a bit of a kludge, required to make
136 # __PACKAGE__->config->{foo} = 'bar';
137 # work in a subclass.
138 # TODO maybe this should be a ClassData option?
139 my $class = blessed($self) || $self;
140 my $meta = Class::MOP::get_metaclass_by_name($class);
141 unless (${ $meta->get_or_add_package_symbol('$_config') }) {
142 # Call merge_hashes to ensure we deep copy the parent
143 # config onto the subclass
144 $self->_config( Catalyst::Utils::merge_hashes($config, {}) );
147 return $self->_config;
150 sub merge_config_hashes {
151 my ( $self, $lefthash, $righthash ) = @_;
153 return Catalyst::Utils::merge_hashes( $lefthash, $righthash );
158 Catalyst::Exception->throw( message => ( ref $_[0] || $_[0] )
159 . " did not override Catalyst::Component::process" );
163 my ($class, $component) = @_;
164 return Devel::InnerPackage::list_packages( $component );
167 __PACKAGE__->meta->make_immutable;
175 =head2 new($app, $arguments)
177 Called by COMPONENT to instantiate the component; should return an object
178 to be stored in the application's component hash.
182 C<< my $component_instance = $component->COMPONENT($app, $arguments); >>
184 If this method is present (as it is on all Catalyst::Component subclasses),
185 it is called by Catalyst during setup_components with the application class
186 as $app and any config entry on the application for this component (for example,
187 in the case of MyApp::Controller::Foo this would be
188 C<< MyApp->config('Controller::Foo' => \%conf >>).
190 The arguments are expected to be a hashref and are merged with the
191 C<< __PACKAGE__->config >> hashref before calling C<< ->new >>
192 to instantiate the component.
194 You can override it in your components to do custom construction, using
198 my ($class, $app, $args) = @_;
199 $args = $class->merge_config_hashes($class->config, $args);
200 return $class->new($app, $args);
205 =head2 $c->config($hashref)
207 =head2 $c->config($key, $value, ...)
209 Accessor for this component's config hash. Config values can be set as
210 key value pair, or you can specify a hashref. In either case the keys
211 will be merged with any existing config settings. Each component in
212 a Catalyst application has its own config hash.
214 The component's config hash is merged with any config entry on the
215 application for this component and passed to C<new()> (as mentioned
216 above at L</COMPONENT>). The recommended practice to access the merged
217 config is to use a Moose attribute for each config entry on the
222 This is the default method called on a Catalyst component in the dispatcher.
223 For instance, Views implement this action to render the response body
224 when you forward to them. The default is an abstract method.
226 =head2 $c->merge_config_hashes( $hashref, $hashref )
228 Merges two hashes together recursively, giving right-hand precedence.
229 Alias for the method in L<Catalyst::Utils>.
231 =head2 $c->expand_modules( $setup_component_config )
233 Return a list of extra components that this component has created. By default,
234 it just looks for a list of inner packages of this component
238 =head1 OPTIONAL METHODS
240 =head2 ACCEPT_CONTEXT($c, @args)
242 Catalyst components are normally initialized during server startup, either
243 as a Class or a Instance. However, some components require information about
244 the current request. To do so, they can implement an ACCEPT_CONTEXT method.
246 If this method is present, it is called during $c->comp/controller/model/view
247 with the current $c and any additional args (e.g. $c->model('Foo', qw/bar baz/)
248 would cause your MyApp::Model::Foo instance's ACCEPT_CONTEXT to be called with
249 ($c, 'bar', 'baz')) and the return value of this method is returned to the
250 calling code in the application rather than the component itself.
254 L<Catalyst>, L<Catalyst::Model>, L<Catalyst::View>, L<Catalyst::Controller>.
258 Catalyst Contributors, see Catalyst.pm
262 This library is free software. You can redistribute it and/or modify it under
263 the same terms as Perl itself.