adding docs

[catagits/Catalyst-Runtime.git] / lib / Catalyst / Component.pm

diff --git a/lib/Catalyst/Component.pm b/lib/Catalyst/Component.pm
index 101f29c..01e38f5 100644 (file)
--- a/lib/Catalyst/Component.pm
+++ b/lib/Catalyst/Component.pm
@@ -9,6 +9,8 @@ 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';
@@ -28,14 +30,18 @@ Catalyst::Component - Catalyst Component Base Class
 
     __PACKAGE__->config( foo => 'bar' );
 
+    has foo => (
+        is => 'ro',
+    );
+
     sub test {
         my $self = shift;
-        return $self->{foo};
+        return $self->foo;
     }
 
     sub forward_to_me {
         my ( $self, $c ) = @_;
-        $c->response->output( $self->{foo} );
+        $c->response->output( $self->foo );
     }
 
     1;
@@ -46,7 +52,7 @@ Catalyst::Component - Catalyst Component Base Class
     # Or just methods
     print $c->comp('MyApp::Model::Something')->test;
 
-    print $c->comp('MyApp::Model::Something')->{foo};
+    print $c->comp('MyApp::Model::Something')->foo;
 
 =head1 DESCRIPTION
 
@@ -56,6 +62,13 @@ 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!)
+
 =cut
 
 __PACKAGE__->mk_classdata('_plugins');
@@ -82,7 +95,7 @@ sub BUILDARGS {
     } elsif (@_ == 2) { # is it ($app, $args) or foo => 'bar' ?
         if (blessed($_[0])) {
             $args = $_[1] if ref($_[1]) eq 'HASH';
-        } elsif (Class::MOP::is_class_loaded($_[0]) &&
+        } elsif (is_class_loaded($_[0]) &&
                 $_[0]->isa('Catalyst') && ref($_[1]) eq 'HASH') {
             $args = $_[1];
         } else {
@@ -126,7 +139,7 @@ sub config {
         # work in a subclass.
         # TODO maybe this should be a ClassData option?
         my $class = blessed($self) || $self;
-        my $meta = Class::MOP::get_metaclass_by_name($class);
+        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
@@ -189,6 +202,19 @@ something like this:
       return $class->new($app, $args);
   }
 
+B<NOTE:> Generally when L<Catalyst> starts, it initializes all the components
+and passes the hashref present in any configutation information to the
+COMPONET method.  For example
+
+    MyApp->config(
+      '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)
@@ -202,7 +228,7 @@ 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 common practice to access the merged
+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.
 
@@ -238,6 +264,39 @@ 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:
+
+    MyApp::Model::FooFactory;
+
+    use Moose;
+    extends 'Catalyst::Model';
+
+    has type => (is=>'ro', required=>1);
+
+    sub ACCEPT_CONTEXT {
+      my ($self, $c, @args) = @_;
+      return bless { args=>\@args }, $self->type;
+    }
+
+    MyApp::Model::Foo->meta->make_immutable;
+    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.
+Remeber 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>.