ruby-2.1-instrumentation-decorator.rb

# Method instrumentation decorator with Ruby 2.1's new "method definition returns method name" feature

class Module
  def instrument(notification_name, mid)
    meth = instance_method(mid)
    define_method(mid) { |*args, &bk|
      ActiveSupport::Notifications.instrument(notification_name) do
        meth.bind(self).call(*args, &bk)
      end
    }
    mid
  end
end

class MyClass
  instrument "my_class.some_expensive_method",
  def some_expensive_method
    # do things
  end
end