From an API perspective, maybe what you want is something event-based,
like Redmine or Chiliproject's plugins system.
Take a look at Apotomo (http://apotomo.de/) for an example of what I'm
talking about. Maybe that approach makes more sense than trying to
emulate some OO inheritance overriding methods in Modules through class
reopening and wanting to use "super" that way. Ruby doesn't support
that and I would recommend you to try another approach if your desired
results are something like Redmine's plugin system.
Cheers, Rodrigo.
Em 17-06-2011 18:00, Jonathan Rochkind escreveu:
This one is driving me crazy, appreciate it VERY much if someone can
even give me some hints at where to look in Rails source code to
understand/debug what's going on, I'm getting lost trying to look
through it.
Rails 3.0.8. I have an engine(gem).
It provides a controller at app/controllers/advanced_controller.rb,
and a corresonding helper at app/helpers/advanced_helper.rb. (And some
views of course).
So far so good, the controller/helper/views are just automatically
available in the application using the gem, great.
But I want to let the local application selective over-ride helper
methods from AdvancedHelper in the engine (and ideally be able to call
'super'). That's a pretty reasonable thing to want to allow, right, a
perfectly reasonable (and I'd think common) design?
Problem is I can't get it to work. Let's say there's a method
#do_something in the engine's app/helpers/advanced_helper.rb.
* If the local app provides an app/helpers/advanced_helper.rb,
then it completely replaces the one from the engine, the one from the
engine isn't loaded at all. (So it has none of it's methods, even
though we just wanted to over-ride one of em). Okay, this isn't
actually TOO unexpected.
* So I provide a helper called, say
local_advanced_helper.rb(LocalAdvancedHelper) in my local app/helpers.
It DOES load. If it implements a #new_method_name, that helper is of
course available in views (including the engine's views, as it
happens). However, if it tries to over-ride the engine's
#do_something ... the local do_something is never called.
The engine's helper seems to be 'included' in the module providing
helper methods to views earlier in the call chain (later in the
'include' order) then my local helpers. So there's no way for local
helpers to over-ride helpers from the engine. (The engine could
theoretically call 'super' to call 'up' to the local view helper with
the same name, but of course that makes little sense, that kind of
dependency is probably seldom appropriate). The ones from the engine
are always first in the call chain, before any view helper modules in
local app.
Can anyone shed any light on what's going on? Including pointing me to
the relevant parts of Rails code? Or suggesting any way I can get
this kind of design (local app can over-ride view helpers provided by
Engine) to work? Or tell me if this is a bug, or by design, or
neither (just didn't consider use case), or what?
Any feedback much appreciated. I've been going crazy trying to figure
this out for hours now. Also posted (in slightly different words) at
http://stackoverflow.com/questions/6380064/rails3-engine-helper-over-ride
Jonathan
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