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 _component_name => ( is => 'ro' );
70 $args = $_[0] if ref($_[0]) eq 'HASH';
71 } elsif (@_ == 2) { # is it ($app, $args) or foo => 'bar' ?
73 $args = $_[1] if ref($_[1]) eq 'HASH';
74 } elsif (Class::MOP::is_class_loaded($_[0]) &&
75 $_[0]->isa('Catalyst') && ref($_[1]) eq 'HASH') {
77 } elsif ($_[0] == $_[1]) {
82 } elsif (@_ % 2 == 0) {
86 return $class->merge_config_hashes( $class->config, $args );
90 my ( $class, $c ) = @_;
92 # Temporary fix, some components does not pass context to constructor
93 my $arguments = ( ref( $_[-1] ) eq 'HASH' ) ? $_[-1] : {};
94 if ( my $next = $class->next::can ) {
95 my ($next_package) = Class::MOP::get_code_info($next);
96 warn "There is a COMPONENT method resolving after Catalyst::Component in ${next_package}.\n";
97 warn "This behavior can no longer be supported, and so your application is probably broken.\n";
98 warn "Your linearized isa hierarchy is: " . join(', ', @{ mro::get_linear_isa($class) }) . "\n";
99 warn "Please see perldoc Catalyst::Upgrading for more information about this issue.\n";
101 return $class->new($c, $arguments);
106 my $config = $self->_config || {};
108 my $newconfig = { %{@_ > 1 ? {@_} : $_[0]} };
110 $self->merge_config_hashes( $config, $newconfig )
113 # this is a bit of a kludge, required to make
114 # __PACKAGE__->config->{foo} = 'bar';
115 # work in a subclass.
116 # TODO maybe this should be a ClassData option?
117 my $class = blessed($self) || $self;
118 my $meta = Class::MOP::get_metaclass_by_name($class);
119 unless ($meta->has_package_symbol('$_config')) {
120 # Call merge_hashes to ensure we deep copy the parent
121 # config onto the subclass
122 $self->_config( Catalyst::Utils::merge_hashes($config, {}) );
125 return $self->_config;
128 sub merge_config_hashes {
129 my ( $self, $lefthash, $righthash ) = @_;
131 return Catalyst::Utils::merge_hashes( $lefthash, $righthash );
136 Catalyst::Exception->throw( message => ( ref $_[0] || $_[0] )
137 . " did not override Catalyst::Component::process" );
140 __PACKAGE__->meta->make_immutable;
148 =head2 new($c, $arguments)
150 Called by COMPONENT to instantiate the component; should return an object
151 to be stored in the application's component hash.
155 C<< my $component_instance = $component->COMPONENT($app, $arguments); >>
157 If this method is present (as it is on all Catalyst::Component subclasses,
158 it is called by Catalyst during setup_components with the application class
159 as $c and any config entry on the application for this component (for example,
160 in the case of MyApp::Controller::Foo this would be
161 C<< MyApp->config('Controller::Foo' => \%conf >>).
162 The arguments are expected to be a hashref and are merged with the
163 C<< __PACKAGE__->config >> hashref before calling C<< ->new >>
164 to instantiate the component.
166 You can override it in your components to do custom instantiation, using
170 my ($class, $app, $args) = @_;
171 $args = $self->merge_config_hashes($self->config, $args);
172 return $class->new($app, $args);
177 =head2 $c->config($hashref)
179 =head2 $c->config($key, $value, ...)
181 Accessor for this component's config hash. Config values can be set as
182 key value pair, or you can specify a hashref. In either case the keys
183 will be merged with any existing config settings. Each component in
184 a Catalyst application has its own config hash.
188 This is the default method called on a Catalyst component in the dispatcher.
189 For instance, Views implement this action to render the response body
190 when you forward to them. The default is an abstract method.
192 =head2 $c->merge_config_hashes( $hashref, $hashref )
194 Merges two hashes together recursively, giving right-hand precedence.
195 Alias for the method in L<Catalyst::Utils>.
197 =head1 OPTIONAL METHODS
199 =head2 ACCEPT_CONTEXT($c, @args)
201 Catalyst components are normally initialized during server startup, either
202 as a Class or a Instance. However, some components require information about
203 the current request. To do so, they can implement an ACCEPT_CONTEXT method.
205 If this method is present, it is called during $c->comp/controller/model/view
206 with the current $c and any additional args (e.g. $c->model('Foo', qw/bar baz/)
207 would cause your MyApp::Model::Foo instance's ACCEPT_CONTEXT to be called with
208 ($c, 'bar', 'baz')) and the return value of this method is returned to the
209 calling code in the application rather than the component itself.
213 L<Catalyst>, L<Catalyst::Model>, L<Catalyst::View>, L<Catalyst::Controller>.
217 Catalyst Contributors, see Catalyst.pm
221 This library is free software. You can redistribute it and/or modify it under
222 the same terms as Perl itself.