From: "William (Bill) Froelich" <wfroelich@...>
Date: 2006-05-06T01:46:11+09:00
Subject: Re: Constant in Ruby.

> Assignment changes the reference for a particular variable.
> 
>   x = "foo"
>   a = x
>   x.gsub(/foo/, "bar")
>   a # -> "bar"
> 
>   x = "foo"
>   a = x
>   x = "bar"
>   a # -> "foo"
> 
> This is true whether you're dealing with variables or constants.

I think I'm might be missing something here.  

In the examples above by just reading the code I would have originally
expected a to return "foo" in both examples (which it does for me
running it through irb).

But after thinking about it a little more, if you use gsub! the first
example does return a #=> "bar" (just a typo I think)

x = "foo"
a = x
x.gsub!(/foo/,"bar")
a #=> "bar"

Please correct me if I am off base here but what I think is happening is
that when we set a = x what we are really doing is creating a reference
a to the same object that x points to (which happens to be "foo").  Then
when we modify the object that x is referencing (changing foo to bar) a
also changes since it points to the same object.

In the second example when we do x = "bar" we are changing x to point to
a new object leaving a pointing to the original object "foo".

I will have to give this some more thought as it has some interesting
implications.  I was originally expecting a to point to a _copy_ of what
x pointed to not the same object.

--Bill