Catalyst::Plugin::PickComponents - Pick up the components for Catalyst.

    use Catalyst qw/
        PickComponents
    /;

    # configure which dir and modules to be loaded
    __PACKAGE__->config->{pick_components} = {
        paths => [ '::Controller', '::Model' ],
        modules => [ 'MyApp::View::TT' ],
        expect_paths => [ '::Controller::Admin', '::Controller::Search' ],
        expect_modules => [ 'MyApp::Controller::Admin', 'MyApp::Controller::Search' ],
    }

    # after ConfigLoader or something else, in YAML myapp.yml or myapp_local.yml
    pick_components:
      paths:
        - ::Controller
        - ::Model
      modules:
        - MyApp::View::TT
      expect_paths:
        - ::Controller::Admin
        - ::Controller::Search
      expect_modules:
        - MyApp::Controller::Admin
        - MyApp::Controller::Search

    # http://www.myapp.com/, myapp_local.yml
    pick_components:
      paths:
        - ::Controller
        - ::Model
      modules:
        - MyApp::View::TT
      expect_paths:
        - ::Controller::Admin
        - ::Controller::Search
      expect_modules:
        - MyApp::Controller::Admin
        - MyApp::Controller::Search

    # http://search.myapp.com/, myapp_local.yml
    pick_components:
      paths:
        - ::Controller::Search
        - ::Model
      modules:
        - MyApp::View::TT
        - MyApp::Controller::Search
        - MyApp::Controller::Root
      expect_paths:
        - ::Controller::Admin
      expect_modules:
        - MyApp::Controller::Admin

    # http://admin.myapp.com/, myapp_local.yml
    pick_components:
      paths:
        - ::Controller::Admin
        - ::Model
      modules:
        - MyApp::View::TT
        - MyApp::Controller::Admin
        - MyApp::Controller::Root
      expect_paths:
        - ::Controller::Search
      expect_modules:
        - MyApp::Controller::Search

package Catalyst::Plugin::PickComponents;

use strict;
use warnings;
use vars qw/$VERSION/;
$VERSION = '0.02';
use Module::Pluggable::Object;
use Catalyst::Utils ();
use MRO::Compat;

sub setup_components {
    my $class = shift;
    
    my $config  = $class->config->{ pick_components };

    unless ($config) {
        return $class->maybe::next::method(@_);
    }
    
    my @paths   = exists $config->{paths}   ? @{ delete $config->{paths} }   : ();
    my @modules = exists $config->{modules} ? @{ delete $config->{modules} } : ();
    my @expect_paths   = exists $config->{expect_paths}   ? @{ delete $config->{expect_paths} }   : ();
    my @expect_modules = exists $config->{expect_modules} ? @{ delete $config->{expect_modules} } : ();
    
    my (@plugins, @expect_plugins);
    if (scalar @paths) {
        my $locator = Module::Pluggable::Object->new(
            search_path => [ map { s/^(?=::)/$class/; $_; } @paths ],
            %$config
        );
        @plugins = $locator->plugins;
    }
    if (scalar @modules) {
        push @plugins, @modules;
    }
    if (scalar @expect_paths) {
        my $locator = Module::Pluggable::Object->new(
            search_path => [ map { s/^(?=::)/$class/; $_; } @expect_paths ],
        );
        @expect_plugins = $locator->plugins;
    }
    if (scalar @expect_modules) {
        push @expect_plugins, @expect_modules;
    }
    my %has = map { $_ => 1 } @plugins;
    $has{$_} = 0 foreach @expect_plugins;
    @plugins = grep { $has{$_} == 1 } keys %has;
    
    # below code is copied from Catalyst.pm sub setup_components
    
    my @comps = sort { length $a <=> length $b } @plugins;
    my %comps = map { $_ => 1 } @comps;
    
    for my $component ( @comps ) {

        # We pass ignore_loaded here so that overlay files for (e.g.)
        # Model::DBI::Schema sub-classes are loaded - if it's in @comps
        # we know M::P::O found a file on disk so this is safe

        Catalyst::Utils::ensure_class_loaded( $component, { ignore_loaded => 1 } );

        my $module  = $class->setup_component( $component );
        my %modules = (
            $component => $module,
            map {
                $_ => $class->setup_component( $_ )
            } grep { 
              not exists $comps{$_}
            } Devel::InnerPackage::list_packages( $component )
        );
        
        for my $key ( keys %modules ) {
            $class->components->{ $key } = $modules{ $key };
        }
    }
}

1;
__END__