From: Eliah Hecht <eliahhecht@...>
Date: 2005-03-01T09:04:37+09:00
Subject: Re: aliasing variables

I know why it doesn't work, I just want to know how to make it work
(if it's doable without making a wrapper object).


On Tue, 1 Mar 2005 08:57:41 +0900, Hal Fulton <hal9000@hypermetrics.com> wrote:
> Eliah Hecht wrote:
> > Is there a way to do something like
> > a = 1
> > alias(b,a)
> > a += 1
> > where the desired effect is that now b == 2?
> >
> 
> It's impossible in the general case, because
> a+=1 literally means a=a+1 (in other words,
> it creates a new object and assigns that to
> a).
> 
> Fixnums are not mutable at all. But if an
> object is mutable, and an operator modifies
> the object rather than creating a new one,
> the behavior you want will happen:
> 
>     a = "cat"
>     b = a
>     a << "hode"
>     puts b        # cathode
> 
> However, assignment never keeps the same
> object:
> 
>     a = "cat"
>     b = a
>     a += "hode"
>     puts b        # cat
> 
> In short: Assignment works on variables, not
> objects; but methods are called on objects,
> not variables.
> 
> Make sense?
> 
> 
> Hal
> 
>