From: James Gray <james@...>
Date: 2008-05-24T03:56:44+09:00
Subject: Re: Ruby observer module

On May 23, 2008, at 1:49 PM, S2 wrote:

> 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'm totally guessing here, but could it be to keep the list from  
changing while it iterates?

James Edward Gray II