Catalyst + Exception::Class + detach

LTjake on 2007-04-09T22:06:29

After re-reading my last post, I realized that I neglected to mention one special exception: $Catalyst::DETACH.

When you call $c->detach( ... ), underneath it calls $c->forward( ... ) then dies with a special detach message. Unfortunately, all of our exception handling will catch this too. It's pretty easy to clean this up in our end action:

sub end : Private {
    my( $self, $c ) = @_;

    if( my( $error ) = @{ $c->error } ) {
        if( $error->message eq $Catalyst::DETACH ) {
            $c->clear_errors;
        }
        else {
            return;
        }
    }

    # continue on as normal...
}

Without that cleanup, you'd get the error screen every time you would call detach().

++ to all this

phaylon on 2007-04-10T13:58:11

I've used custom exceptions for ResourceNotFound, InvalidIdentifier and such regularly in applications in the past and it worked quite well. I also experimented with an un-auto like catching mechanism. For example, the chain segment Foo::Bar::load would throw an ResourceNotFound::Bar exception if it can't find a bar with the passed ID. It would then search in Foo::Bar, and then in Foo for exception handling actions that fit the criteria (catching ResourceNotFound::Bar, ResourceNotFound or FlowException).

I haven't yet come up with a final, clean syntax yet, but I imagine something like:

Re:++ to all this

LTjake on 2007-04-10T17:57:29

Great idea! It seems like we're inching towards a more robust idea of exception handling.

Right now I'm pretty happy encapsulating some logic inside each exception class -- though something more closely tied to the application would likely be better in some instances.