From: "Hal E. Fulton" <hal9000@...>
Date: 2003-06-14T03:31:08+09:00
Subject: Re: does each work on a copy?

----- Original Message ----- 
From: "Robert Klemme" <bob.news@gmx.net>
Newsgroups: comp.lang.ruby
To: "ruby-talk ML" <ruby-talk@ruby-lang.org>
Sent: Friday, June 13, 2003 5:31 AM
Subject: Re: does each work on a copy?


> > > It seems to hold a copy of the reference...
> >
> > No, it doesn't. When you do a:
> 
> Sorry, but in fact you're wrong.  The reference is copied indeed.
> 
> > a = "Hello world, nice to meet you!".split(' ')
> > a.each { |word| word = "lala" }
> > p a
> > ["Hello", "world,", "nice", "to", "meet", "you!"]
> >
> > You're binding word to a different object, not changing the objects
> themselves.
> 
> Binding "word" to another object is indeed done by copying the reference
> to the other object.  Or in other terms, after this assignment there is
> one more reference to the object.

I think part of the confusion is the way other 
languages do things.

In C++, for example, assignment is a method, 
and a reference is an lvalue. So if you pass
in a reference and assign to it, you do indeed
change the object referred to.

In Ruby, assignment is not a method, and an
object reference is not an lvalue.

Hal