[Catalyst] Programmatic way to determine the needed number of captures for an action?

[Ash Berlin]

John Napiorkowski wrote:
> Hi,
> 
> I have a question about $c->uri_for and chained
> actions.
> 
> I've really enjoyed having this feature to
> programmatically create urls for me in the code.  It's
> one of the greatest things about Catalyst I think. 
> However one thing that is a bit tricky is that when
> using $c->uri_for with chained actions you have to be
> careful to supply the correct number of captures.  If
> you give too few or too many then $c->uri_for will
> return an undef.
> 
> So something I am trying to figure out is how to
> determine in code (without knowing in advance) how
> many captures a given chained action will expect so
> that I can supply it correctly.
> 
> You can look at the Args and CaptureArgs attribute for
> a single action, but if that action is an endpoint in
> a chain, and actions earlier in the chain require
> Args, I can't find a straightforward way to get the
> total number of required Args for a given Chain
> endpoint.
> 
> Here's an example of my issue:
> 
> Let's say I have a controller with two actions 'base'
> and 'item'.  item is chained to base, with base as the
> root and item requires an argument:
> 
> Controller One;
> 
> sub base Chained('/') CaptureArgs(0) {}
> 
> sub item (Chained('base') Args(1) {}
> 
> Now in my second controller I have:
> 
> Controller Two
> 
> sub base Chained('/') CaptureArgs(1) {}
> 
> sub item (Chained('base') Args(1) {}
> 
> For controller one I can get the URL with:
> 
> $c->uri_for($->controller(..)->action_for('base'));
> 
> But for the second controller I'd need:
> 
> $c->uri_for($->controller(..)->action_for('base'),
> [$capture]);
> 
> What I am trying to do is to write some code that
> looks at the number of arguments a given action needs
> and automatically supplies that number off the current
> captures list.
> 
> I can see that I could do this by adding some
> additional metadata fields to my custom Action
> Classes, but I was trying to see if there was a
> canonically correct way to do this in Catalyst.
> 
> Anyone know?
> 
> Thanks!
> 
> John
> 

This has been discussed before, tho a fully satisfactory solution never 
appeared. Something that we touched upon that could work was to have a 
stack of actions which been used/hit in the chain - though this wouldn't 
help when going cross controller.

But yes, its something that has been niggling me as well.

Ash