[PATCH] ActiveSupport::Callbacks

In the current patch, AR tests aren't passing. Something to do with the SetupAndTeardown code not working. Still in the works and kind of experimental.

Good start. I'd like to move away from inheritable_attribute though in favor of piggybacking on existing Ruby method calling semantics. I was thinking of extracting the pattern I used here: simple instance variables with delegation to superclass, so changing the superclass attribute after subclassing still affects the subclasses. With inheritable_attribute, the value is copied when subclassed so changes don't propagate. See superclass_delegating_attribute in Class core_ext and attr_accessor_with_default in Module core_ext for similar ideas.

Yep, and AR tests pass again (as well as everything else).

I didn't tackle AR::Validations yet. It follows a similar pattern as callbacks but has a few exceptions.

Maybe this is a different ticket, well should be posted in the mailing list first but, I'd like to see the method callback technique deprecated. eg.

def after_save
  "stuff"
end

def validate
  "stuff"
end

and use this instead

after_save do |r|
  "stuff"
end

validate do |r|
  "stuff"
end

jeremy, ready to commit unless anyone else has any objections.

I like it. I was initially concerned that a single implementation wouldn't work for all these cases, but it appears it does. We'll have to expose the run_callbacks termination condition eventually since false return values doesn't apply to controller filters.

I'm not sure if I'm going be able to monkey filters around ActiveSupport::Callbacks. Its a really different code base. I'll give it a try later today.

By "termination condition" do you mean something like this, "run_callbacks(callbacks, :halt_on => false)"?

O, found another. Refactored dispatcher with ActiveSupport::Callbacks and added a termination condition option to run_callbacks.

(In [8664]) Extract ActiveSupport::Callbacks from Active Record, test case setup and teardown, and ActionController::Dispatcher. Closes #10727.