1 package Catalyst::Component;
5 use Class::MOP::Object;
7 use Class::C3::Adopt::NEXT;
10 use Scalar::Util 'blessed';
11 use namespace::clean -except => 'meta';
13 with 'MooseX::Emulate::Class::Accessor::Fast';
14 with 'Catalyst::ClassData';
19 Catalyst::Component - Catalyst Component Base Class
23 # lib/MyApp/Model/Something.pm
24 package MyApp::Model::Something;
26 use base 'Catalyst::Component';
28 __PACKAGE__->config( foo => 'bar' );
36 my ( $self, $c ) = @_;
37 $c->response->output( $self->{foo} );
42 # Methods can be a request step
43 $c->forward(qw/MyApp::Model::Something forward_to_me/);
46 print $c->comp('MyApp::Model::Something')->test;
48 print $c->comp('MyApp::Model::Something')->{foo};
52 This is the universal base class for Catalyst components
53 (Model/View/Controller).
55 It provides you with a generic new() for instantiation through Catalyst's
56 component loader with config() support and a process() method placeholder.
60 __PACKAGE__->mk_classdata('_plugins');
61 __PACKAGE__->mk_classdata('_config');
63 has catalyst_component_name => ( is => 'ro' ); # Cannot be required => 1 as context
64 # class @ISA component - HATE
65 # Make accessor callable as a class method, as we need to call setup_actions
66 # on the application class, which we don't have an instance of, ewwwww
67 # Also, naughty modules like Catalyst::View::JSON try to write to _everything_,
68 # so spit a warning, ignore that (and try to do the right thing anyway) here..
69 around catalyst_component_name => sub {
70 my ($orig, $self) = (shift, shift);
71 Carp::cluck("Tried to write to the catalyst_component_name accessor - is your component broken or just mad? (Write ignored - using default value.)") if scalar @_;
72 blessed($self) ? $self->$orig() || blessed($self) : $self;
80 $args = $_[0] if ref($_[0]) eq 'HASH';
81 } elsif (@_ == 2) { # is it ($app, $args) or foo => 'bar' ?
83 $args = $_[1] if ref($_[1]) eq 'HASH';
84 } elsif (Class::MOP::is_class_loaded($_[0]) &&
85 $_[0]->isa('Catalyst') && ref($_[1]) eq 'HASH') {
87 } elsif ($_[0] == $_[1]) {
92 } elsif (@_ % 2 == 0) {
96 return $class->merge_config_hashes( $class->config, $args );
100 my ( $class, $c ) = @_;
102 # Temporary fix, some components does not pass context to constructor
103 my $arguments = ( ref( $_[-1] ) eq 'HASH' ) ? $_[-1] : {};
104 if ( my $next = $class->next::can ) {
105 my ($next_package) = Class::MOP::get_code_info($next);
106 warn "There is a COMPONENT method resolving after Catalyst::Component in ${next_package}.\n";
107 warn "This behavior can no longer be supported, and so your application is probably broken.\n";
108 warn "Your linearized isa hierarchy is: " . join(', ', @{ mro::get_linear_isa($class) }) . "\n";
109 warn "Please see perldoc Catalyst::Upgrading for more information about this issue.\n";
111 return $class->new($c, $arguments);
116 my $config = $self->_config || {};
118 my $newconfig = { %{@_ > 1 ? {@_} : $_[0]} };
120 $self->merge_config_hashes( $config, $newconfig )
123 # this is a bit of a kludge, required to make
124 # __PACKAGE__->config->{foo} = 'bar';
125 # work in a subclass.
126 # TODO maybe this should be a ClassData option?
127 my $class = blessed($self) || $self;
128 my $meta = Class::MOP::get_metaclass_by_name($class);
129 unless ($meta->has_package_symbol('$_config')) {
130 # Call merge_hashes to ensure we deep copy the parent
131 # config onto the subclass
132 $self->_config( Catalyst::Utils::merge_hashes($config, {}) );
135 return $self->_config;
138 sub merge_config_hashes {
139 my ( $self, $lefthash, $righthash ) = @_;
141 return Catalyst::Utils::merge_hashes( $lefthash, $righthash );
146 Catalyst::Exception->throw( message => ( ref $_[0] || $_[0] )
147 . " did not override Catalyst::Component::process" );
150 __PACKAGE__->meta->make_immutable;
158 =head2 new($c, $arguments)
160 Called by COMPONENT to instantiate the component; should return an object
161 to be stored in the application's component hash.
165 C<< my $component_instance = $component->COMPONENT($app, $arguments); >>
167 If this method is present (as it is on all Catalyst::Component subclasses,
168 it is called by Catalyst during setup_components with the application class
169 as $c and any config entry on the application for this component (for example,
170 in the case of MyApp::Controller::Foo this would be
171 C<< MyApp->config('Controller::Foo' => \%conf >>).
172 The arguments are expected to be a hashref and are merged with the
173 C<< __PACKAGE__->config >> hashref before calling C<< ->new >>
174 to instantiate the component.
176 You can override it in your components to do custom instantiation, using
180 my ($class, $app, $args) = @_;
181 $args = $self->merge_config_hashes($self->config, $args);
182 return $class->new($app, $args);
187 =head2 $c->config($hashref)
189 =head2 $c->config($key, $value, ...)
191 Accessor for this component's config hash. Config values can be set as
192 key value pair, or you can specify a hashref. In either case the keys
193 will be merged with any existing config settings. Each component in
194 a Catalyst application has its own config hash.
198 This is the default method called on a Catalyst component in the dispatcher.
199 For instance, Views implement this action to render the response body
200 when you forward to them. The default is an abstract method.
202 =head2 $c->merge_config_hashes( $hashref, $hashref )
204 Merges two hashes together recursively, giving right-hand precedence.
205 Alias for the method in L<Catalyst::Utils>.
207 =head1 OPTIONAL METHODS
209 =head2 ACCEPT_CONTEXT($c, @args)
211 Catalyst components are normally initialized during server startup, either
212 as a Class or a Instance. However, some components require information about
213 the current request. To do so, they can implement an ACCEPT_CONTEXT method.
215 If this method is present, it is called during $c->comp/controller/model/view
216 with the current $c and any additional args (e.g. $c->model('Foo', qw/bar baz/)
217 would cause your MyApp::Model::Foo instance's ACCEPT_CONTEXT to be called with
218 ($c, 'bar', 'baz')) and the return value of this method is returned to the
219 calling code in the application rather than the component itself.
223 L<Catalyst>, L<Catalyst::Model>, L<Catalyst::View>, L<Catalyst::Controller>.
227 Catalyst Contributors, see Catalyst.pm
231 This library is free software. You can redistribute it and/or modify it under
232 the same terms as Perl itself.