Observational and cache sweepers

[liveh2o]

I ran into a weird issue when I tried to add a cache sweeper while using the observational gem (which I really like by the way).

Whenever the sweeper is called, it is raising a 'method undefined' exception in lib/observational/observable.rb:21 when calling 'observes_action' on the sweeper's observer (since the sweeper's observer is a regular Observer, not an Observational::Observer).

Here's the relevant stacktrace:

NoMethodError (undefined method observes_action?' for #<Admin::RegionsController:0x1033480b0>): observational (0.2.5) lib/observational/observable.rb:21:inobservers_for'
observational (0.2.5) lib/observational/observable.rb:21:in select' observational (0.2.5) lib/observational/observable.rb:21:inobservers_for'
observational (0.2.5) lib/observational/observable.rb:31:in notify_observers' observational (0.2.5) lib/observational/active_record_observers.rb:4:insend'
observational (0.2.5) lib/observational/active_record_observers.rb:4:in `run_callbacks'

I was able to fix the issue by adding a check for the :observes_action? method to observers_for:

  def observers_for(action)
    observers.select { |o| o.observes_action?(action) if o.respond_to?(:observes_action?) }
  end

I'm not really sure if this is best solution, but its working for me right now. Anyway, I thought you should know. Oh, and I'm using Ruby 1.8.7, Rails 2.3.5, RubyGems 1.3.6, and Observational 0.2.5.

Let me know if you need anymore info.

[liveh2o]

I've forked this repo here and committed my fix to it.