From: Hal Fulton <hal9000@...>
Date: 2005-03-01T08:57:41+09:00
Subject: Re: aliasing variables

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