From: Robert Dober <robert.dober@...>
Date: 2008-08-29T22:40:57+09:00
Subject: Re: Please don't flame me...why is there no "++" in Ruby again ?

On Fri, Aug 29, 2008 at 10:10 AM, Lars Christensen <larsch@belunktum.dk> wrote:

> I think the OP deserves the fuller explanation;
You are right, but I did after realising my error ;).
 AAMOF it has *nothing* to do with the immutability of integers.
OP asked for syntactic sugar.
> Why are integers
> immutable? Consider this:
>
> a = 2
> b = a
> a++
>
> Since everything is an object, 'a' references the object '2' and b
> should reference it too after the assignment. Then 'a++' should
> increment the object referenced by both a and b? This would of course
> be possible, but it would be a rather huge performance penalty to keep
> something as simple as integers as references to objects everywhere.
>
> Ruby keeps 'small-enough' integers in the object reference (pointer)
> to improve performance. Hence 'b = a' results in an actual copy being
> taken of the value '2'. If you increment 'b', 'a' would retain its old
> value, breaking the concept that a variable is always just a
> reference. Ruby opts for immutable Integers instead.
>

Nevertheless all you said makes perfect sense of course.
R.