From: S2 <x@...>
Date: 2008-05-24T03:49:57+09:00
Subject: Ruby observer module

Hi,
I am reading Design Patterns in Ruby, and was looking at the code of the
observer module. On line 184, in notify_observers, there is a loop on all
registered observers:

  for i in @observer_peers.dup
    i.update(*arg)
  end

Why is there a "dup" on the array? Is that really necessary? Isn't this a
waste of memory? I am sure there is a really good explanation, but I don't
grasp it.

I also have another question: why does the subject (the notifying class)
need to call "changed"? Wouldn't it be sufficient to call notify_observers?
I mean, if I call notify_observers in the Subject class, doesn't that imply
has something has changed?


-- 
http://s2.diffuse.it/