From Decorator Pattern to Before Filter 1

Looking at my previous post on the Decorator Pattern in ruby, I thought: 'here's an elegant solution to inject behaviour in an object method while respecting encapsulation... but what could be the use of it, a part from unmixing creme out of my coffee'.

- Hummm well in this rails plugin i started writing it could fit in....

- yes but as a more general solution...

- mmmm...Filtering of course !!! Just like the 'before_filter' in rails controller.

- you mean like that :




- as a rough start it gives you the idea. But we would need something more dsl-ish, like our reference in rails controller: 'before_filter :login_required'

- so i guess the next step is to give it a method to call on like spoon_required:



- ok, that was easy but the module is still tied to the class it's decorating. We need to abstract away the method we're filtering ('cost') in the module so it could be any method in the class. So this requires a little bit of ruby's magic :



- I think we've done the hardest part. The rest in episode 2.