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 # Uncomment once sane to do so
117 #Carp::cluck("config method called on instance") if ref $self;
118 my $config = $self->_config || {};
120 my $newconfig = { %{@_ > 1 ? {@_} : $_[0]} };
122 $self->merge_config_hashes( $config, $newconfig )
125 # this is a bit of a kludge, required to make
126 # __PACKAGE__->config->{foo} = 'bar';
127 # work in a subclass.
128 # TODO maybe this should be a ClassData option?
129 my $class = blessed($self) || $self;
130 my $meta = Class::MOP::get_metaclass_by_name($class);
131 unless ($meta->has_package_symbol('$_config')) {
132 # Call merge_hashes to ensure we deep copy the parent
133 # config onto the subclass
134 $self->_config( Catalyst::Utils::merge_hashes($config, {}) );
137 return $self->_config;
140 sub merge_config_hashes {
141 my ( $self, $lefthash, $righthash ) = @_;
143 return Catalyst::Utils::merge_hashes( $lefthash, $righthash );
148 Catalyst::Exception->throw( message => ( ref $_[0] || $_[0] )
149 . " did not override Catalyst::Component::process" );
152 __PACKAGE__->meta->make_immutable;
160 =head2 new($c, $arguments)
162 Called by COMPONENT to instantiate the component; should return an object
163 to be stored in the application's component hash.
167 C<< my $component_instance = $component->COMPONENT($app, $arguments); >>
169 If this method is present (as it is on all Catalyst::Component subclasses,
170 it is called by Catalyst during setup_components with the application class
171 as $c and any config entry on the application for this component (for example,
172 in the case of MyApp::Controller::Foo this would be
173 C<< MyApp->config('Controller::Foo' => \%conf >>).
174 The arguments are expected to be a hashref and are merged with the
175 C<< __PACKAGE__->config >> hashref before calling C<< ->new >>
176 to instantiate the component.
178 You can override it in your components to do custom instantiation, using
182 my ($class, $app, $args) = @_;
183 $args = $self->merge_config_hashes($self->config, $args);
184 return $class->new($app, $args);
189 =head2 $c->config($hashref)
191 =head2 $c->config($key, $value, ...)
193 Accessor for this component's config hash. Config values can be set as
194 key value pair, or you can specify a hashref. In either case the keys
195 will be merged with any existing config settings. Each component in
196 a Catalyst application has its own config hash.
200 This is the default method called on a Catalyst component in the dispatcher.
201 For instance, Views implement this action to render the response body
202 when you forward to them. The default is an abstract method.
204 =head2 $c->merge_config_hashes( $hashref, $hashref )
206 Merges two hashes together recursively, giving right-hand precedence.
207 Alias for the method in L<Catalyst::Utils>.
209 =head1 OPTIONAL METHODS
211 =head2 ACCEPT_CONTEXT($c, @args)
213 Catalyst components are normally initialized during server startup, either
214 as a Class or a Instance. However, some components require information about
215 the current request. To do so, they can implement an ACCEPT_CONTEXT method.
217 If this method is present, it is called during $c->comp/controller/model/view
218 with the current $c and any additional args (e.g. $c->model('Foo', qw/bar baz/)
219 would cause your MyApp::Model::Foo instance's ACCEPT_CONTEXT to be called with
220 ($c, 'bar', 'baz')) and the return value of this method is returned to the
221 calling code in the application rather than the component itself.
225 L<Catalyst>, L<Catalyst::Model>, L<Catalyst::View>, L<Catalyst::Controller>.
229 Catalyst Contributors, see Catalyst.pm
233 This library is free software. You can redistribute it and/or modify it under
234 the same terms as Perl itself.