From: James Edward Gray II <james@...>
Date: 2005-06-18T08:58:34+09:00
Subject: Re: Why do arrays work this way?

On Jun 17, 2005, at 6:51 PM, Nigel Wilkinson wrote:

> Hi folks
>
> I'm using ruby 1.8.2 as comes with Mandriva 2005LE and get the  
> following behaviour with arrays which doesn't seem logical to me.

[snip examples]

> so what's the logic behind 'a' & 'c' changing when I change 'b'.
>
> Is this a bug? and if not what's the reasoning behind this  
> behaviour please.

In Ruby, everything is an object, but variables are just references  
to those objects.  Your `b=a` sets b to reference the same object as  
a.  Thus, when you make a change to one, they all change.  Now, if  
you used `b=a.dup` b would be set to reference a copy of a, and the  
changes would not filter over.

Try playing around in irb as you have been doing, but calling  
object_id() on the arrays to seem which objects are the same.

Hope that helps.

James Edward Gray II