[Catalyst] My experience porting to CataMoose

[Matt S Trout]

On Wed, May 13, 2009 at 04:13:06AM +0200, Sebastian Willert wrote:
> On Wed, 2009-05-13 at 07:21 +0900, Daisuke Maki wrote:
> > >> 2. Hooking to methods that Plugins use via method modifiers breaks
> > >> method dispatch
> > >>
> > >> I got bit by this while depending on Catalyst::Plugin::Unicode, and
> > >> trying to hook a custom error handling mechanism at finalize().
> > > 
> > > <snip explanation>
> > > 
> > > Hmm, that certainally looks like a bug to me..
> > > 
> > > Any chance that I could get you to write a test case or two for this issue?
> > 
> > I get it now, it has to do with when setup() and method modifiers run:
> > 
> > <snip example code>
> >
> >   If you intend to use Moose's method modifiers in your app, do so
> >   /AFTER/ Catalyst->setup has been called.
> > 
> > or some such
> 
> First of all: thanks for the pointer, you have ended a lot of hair
> pulling for me. But IMO this is not just a common gotcha but a serious
> bug.

Wrong, sorry. It's an inevitable caveat. The point is that plugin setup
changes the app's @ISA, so it simply isn't safe to run modifiers before
->setup, or more specifically until after ->setup_plugins.

> I have a few plugins I am trying to convert to Moose::Role's that
> desperately need both
>   before 'setup_components'
> and
>   after 'finalize'
> 
> This just isn't going to work one way or the other :(

Fortunately, setup_plugins happens -before- setup_components so you can
apply a role any time after that and it'll all work fine.

> Maybe I can whip up some testcases tomorrow ..

Maybe you can whip up some documentation tomorrow?

Though it would be nice if modifier application before ->setup_plugins
produced a warning explaining why that's bad, wrong, and not going to work.

-- 
        Matt S Trout         Catalyst and DBIx::Class consultancy with a clue
     Technical Director      and a commit bit: http://shadowcat.co.uk/catalyst/
 Shadowcat Systems Limited
  mst (@) shadowcat.co.uk        http://shadowcat.co.uk/blog/matt-s-trout/