thanks for the replies. I spent few hours to study the source code of catalyst, catalyst::component and i think i grasped the basic idea of exposing one class into another. here is how i see it work in my case:

every adaptor class is loaded as a component of the frontend base class. at application startup, every component is required and instantiated via new(). The instances are then stored as a class data of the frontend base class, making them some sort of singleton objects. 

package MyApp::Component;
use base qw/Class::Accessor::Fast Class::Data::Inheritable/;

1;

package Frontend::Base;
use base 'MyApp::Component';
__PACKAGE__->mk_classdata(components);

sub load_components {
    # use module::pluggable
    # for each adaptor that module::pluggable found
    # load the adaptor($comp)
    $class->load_component($comp);
}

sub load_component {
    my ($class, $comp) = @_;
    $class->components->{ $component_name } = $comp->new();
}

sub adaptor { 
    my ($class, $model) = @_;
    return $class->components->{ $component_name };
}

1;

package Frontend::Report;
use base 'Frontend::Base';

sub do_report {
    $class->adaptor('Adaptor::Report')->method;
}

1;

[download]
also looked at DBIx::Class and it uses Class::C3 and Class::C3::Componentised. i suspect that's another way to accomplish my goal.

In reply to Re: MVC question: way to expose API by Qiang
in thread MVC question: way to expose API by Qiang

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