package Catalyst::Component;

use Moose;
use Class::MOP;
use Class::MOP::Object;
use Catalyst::Utils;
use Class::C3::Adopt::NEXT;
use Devel::InnerPackage ();
use MRO::Compat;
use mro 'c3';
use Scalar::Util 'blessed';
use Class::Load 'is_class_loaded';
use Moose::Util 'find_meta';
use namespace::clean -except => 'meta';

with 'MooseX::Emulate::Class::Accessor::Fast';
with 'Catalyst::ClassData';

=head1 NAME

Catalyst::Component - Catalyst Component Base Class


    # lib/MyApp/Model/
    package MyApp::Model::Something;

    use base 'Catalyst::Component';

    __PACKAGE__->config( foo => 'bar' );

    has foo => (
        is => 'ro',

    sub test {
        my $self = shift;
        return $self->foo;

    sub forward_to_me {
        my ( $self, $c ) = @_;
        $c->response->output( $self->foo );


    # Methods can be a request step
    $c->forward(qw/MyApp::Model::Something forward_to_me/);

    # Or just methods
    print $c->comp('MyApp::Model::Something')->test;

    print $c->comp('MyApp::Model::Something')->foo;


This is the universal base class for Catalyst components

It provides you with a generic new() for component construction through Catalyst's
component loader with config() support and a process() method placeholder.

B<Note> that calling C<< $self->config >> inside a component is strongly
not recommended - the correctly merged config should have already been
passed to the constructor and stored in attributes - accessing
the config accessor directly from an instance is likely to get the
wrong values (as it only holds the class wide config, not things loaded
from the config file!)



has catalyst_component_name => ( is => 'ro' ); # Cannot be required => 1 as context
                                       # class @ISA component - HATE
# Make accessor callable as a class method, as we need to call setup_actions
# on the application class, which we don't have an instance of, ewwwww
# Also, naughty modules like Catalyst::View::JSON try to write to _everything_,
# so spit a warning, ignore that (and try to do the right thing anyway) here..
around catalyst_component_name => sub {
    my ($orig, $self) = (shift, shift);
    Carp::cluck("Tried to write to the catalyst_component_name accessor - is your component broken or just mad? (Write ignored - using default value.)") if scalar @_;
    blessed($self) ? $self->$orig() || blessed($self) : $self;

    my $class = shift;
    my $args = {};

    if (@_ == 1) {
        $args = $_[0] if ref($_[0]) eq 'HASH';
    } elsif (@_ == 2) { # is it ($app, $args) or foo => 'bar' ?
        if (blessed($_[0])) {
            $args = $_[1] if ref($_[1]) eq 'HASH';
        } elsif (is_class_loaded($_[0]) &&
                $_[0]->isa('Catalyst') && ref($_[1]) eq 'HASH') {
            $args = $_[1];
        } else {
            $args = +{ @_ };
    } elsif (@_ % 2 == 0) {
        $args = +{ @_ };

    return $class->merge_config_hashes( $class->config, $args );

    my ( $class, $c ) = @_;

    # Temporary fix, some components does not pass context to constructor
    my $arguments = ( ref( $_[-1] ) eq 'HASH' ) ? $_[-1] : {};
    if ( my $next = $class->next::can ) {
      my ($next_package) = Class::MOP::get_code_info($next);
      warn "There is a COMPONENT method resolving after Catalyst::Component in ${next_package}.\n";
      warn "This behavior can no longer be supported, and so your application is probably broken.\n";
      warn "Your linearized isa hierarchy is: " . join(', ', @{ mro::get_linear_isa($class) }) . "\n";
      warn "Please see perldoc Catalyst::Upgrading for more information about this issue.\n";
    return $class->new($c, $arguments);

sub config {
    my $self = shift;
    # Uncomment once sane to do so
    #Carp::cluck("config method called on instance") if ref $self;
    my $config = $self->_config || {};
    if (@_) {
        my $newconfig = { %{@_ > 1 ? {@_} : $_[0]} };
            $self->merge_config_hashes( $config, $newconfig )
    } else {
        # this is a bit of a kludge, required to make
        # __PACKAGE__->config->{foo} = 'bar';
        # work in a subclass.
        # TODO maybe this should be a ClassData option?
        my $class = blessed($self) || $self;
        my $meta = find_meta($class);
        unless (${ $meta->get_or_add_package_symbol('$_config') }) {
            # Call merge_hashes to ensure we deep copy the parent
            # config onto the subclass
            $self->_config( Catalyst::Utils::merge_hashes($config, {}) );
    return $self->_config;

sub merge_config_hashes {
    my ( $self, $lefthash, $righthash ) = @_;

    return Catalyst::Utils::merge_hashes( $lefthash, $righthash );

sub process {

    Catalyst::Exception->throw( message => ( ref $_[0] || $_[0] )
          . " did not override Catalyst::Component::process" );

sub expand_modules {
    my ($class, $component) = @_;
    return Devel::InnerPackage::list_packages( $component );




=head1 METHODS

=head2 new($app, $arguments)

Called by COMPONENT to instantiate the component; should return an object
to be stored in the application's component hash.


C<< my $component_instance = $component->COMPONENT($app, $arguments); >>

If this method is present (as it is on all Catalyst::Component subclasses),
it is called by Catalyst during setup_components with the application class
as $app and any config entry on the application for this component (for example,
in the case of MyApp::Controller::Foo this would be
C<< MyApp->config('Controller::Foo' => \%conf >>).

The arguments are expected to be a hashref and are merged with the
C<< __PACKAGE__->config >> hashref before calling C<< ->new >>
to instantiate the component.

You can override it in your components to do custom construction, using
something like this:

      my ($class, $app, $args) = @_;
      $args = $class->merge_config_hashes($class->config, $args);
      return $class->new($app, $args);

B<NOTE:> Generally when L<Catalyst> starts, it initializes all the components
and passes the hashref present in any configuration information to the
COMPONENT method.  For example

      'Model::Foo' => {
        bar => 'baz',

You would expect COMPONENT to be called like this ->COMPONENT( 'MyApp', +{ bar=>'baz'});

This would happen ONCE during setup.

=head2 $c->config

=head2 $c->config($hashref)

=head2 $c->config($key, $value, ...)

Accessor for this component's config hash. Config values can be set as
key value pair, or you can specify a hashref. In either case the keys
will be merged with any existing config settings. Each component in
a Catalyst application has its own config hash.

The component's config hash is merged with any config entry on the
application for this component and passed to C<new()> (as mentioned
above at L</COMPONENT>). The recommended practice to access the merged
config is to use a Moose attribute for each config entry on the
receiving component.

=head2 $c->process()

This is the default method called on a Catalyst component in the dispatcher.
For instance, Views implement this action to render the response body
when you forward to them. The default is an abstract method.

=head2 $c->merge_config_hashes( $hashref, $hashref )

Merges two hashes together recursively, giving right-hand precedence.
Alias for the method in L<Catalyst::Utils>.

=head2 $c->expand_modules( $setup_component_config )

Return a list of extra components that this component has created. By default,
it just looks for a list of inner packages of this component



=head2 ACCEPT_CONTEXT($c, @args)

Catalyst components are normally initialized during server startup, either
as a Class or a Instance. However, some components require information about
the current request. To do so, they can implement an ACCEPT_CONTEXT method.

If this method is present, it is called during $c->comp/controller/model/view
with the current $c and any additional args (e.g. $c->model('Foo', qw/bar baz/)
would cause your MyApp::Model::Foo instance's ACCEPT_CONTEXT to be called with
($c, 'bar', 'baz')) and the return value of this method is returned to the
calling code in the application rather than the component itself.

B<NOTE:> All classes that are L<Catalyst::Component>s will have a COMPONENT
method, but classes that are intended to be factories or generators will
have ACCEPT_CONTEXT.  If you have initialization arguments (such as from
configuration) that you wish to expose to the ACCEPT_CONTEXT you should
proxy them in the factory instance.  For example:


    use Moose;
    extends 'Catalyst::Model';

    has type => (is=>'ro', required=>1);

      my ($self, $c, @args) = @_;
      return bless { args=>\@args }, $self->type;

    MyApp::Model::Foo->config( type => 'Type1' );

And in a controller:

    my $type = $c->model('FooFactory', 1,2,3,4): # $type->isa('Type1')

B<NOTE:> If you define a ACCEPT_CONTEXT method it MUST check to see if the
second argument is blessed (is a context) or not (is an application class name) and
it MUST return something valid for the case when the scope is application.  This is
required because a component maybe be called from the application scope even if it
requires a context and you must prevent errors from being issued if this happens.
Remember not all components that ACCEPT_CONTEXT actually need or use context information
(and there is a school of thought that suggestions doing so is a design error anyway...)

=head1 SEE ALSO

L<Catalyst>, L<Catalyst::Model>, L<Catalyst::View>, L<Catalyst::Controller>.

=head1 AUTHORS

Catalyst Contributors, see


This library is free software. You can redistribute it and/or modify it under
the same terms as Perl itself.