From: Morton Goldberg <m_goldberg@...>
Date: 2007-09-30T10:48:32+09:00
Subject: Re: a = Dog.new # a is not a pointer and not a reference?

On Sep 29, 2007, at 8:18 PM, SpringFlowers AutumnMoon wrote:

> Come to think about it, a pointer is very clear cut... an alias is  
> very
> clear cut.  but when it is "reference", then you have to think whether
> it is the pointer behavior or the alias behavior.

No, you do not. Ruby has it own semantics, which do not correspond  
with the semantics of C or C++. Trying to impose the semantics of  
other languages onto Ruby isn't going to work. It's best to drop such  
baggage and start fresh.

Try this. Without going into implementation details, of which I am  
ignorant, a Ruby variable establishes an association between an  
identifier and an object [*]. The association is specific to a  
particular lexical scope and to a particular execution extent.  
Therefore the same identifier can be associated (refer to) different  
objects in different scopes and different objects at different points  
of the execution. Such an association should perhaps more strictly be  
called a binding rather than a reference, but 'reference' is often  
used in informal discourse.

This the way I think of it. It's an old Lisp programmer's point of  
view, but I think it's a reasonably good model for Ruby. It has  
worked well for me -- kept me out of trouble. And if I'm guilty of  
wrongly imposing Lisp semantics on Ruby, I'm sure I'll be corrected :)

Regards, Morton

[*] Yes, I know this is not the whole story. I'm trying to keep  
things simple.