From: Robert Dober <robert.dober@...>
Date: 2007-07-12T04:50:05+09:00
Subject: Re: Why no next! method in integer class ?

On 7/11/07, dblack@wobblini.net <dblack@wobblini.net> wrote:
> Hi --
>
> On Thu, 12 Jul 2007, bradjpeek wrote:
>
> > Just curious...
> >
> > The string class contains a next! method.   Is there a technical
> > reason for not having a next! method in the integer class, or was it
> > just a language designer preference?
>
> Probably both :-)  The technical reason is that integers are immediate
> values, so you can't increment them.  In other words:
>
>    a = 1
>    a.next!
>
> That would mean that 1 is now 2, which would not be good.  In theory
> you could change the binding of a, so that it was now bound to 2
> instead of 1; but that's out of keeping with how these things
> generally work (e.g., with strings), which is that the object is
> mutated while the variable bindings are not affected.  Doing it this
> way reinforces how objects and variables relate to each other in Ruby,
> and avoids having assignments that are masquerading as method calls.
>
> For more on this, search the archives for discussions on ++, which is
> absent from the language for very similar reasons.
Too kind of you David to omit my stupid RCR suggestion of
Integer#succ! and Integer#pred!, but it is worth searching for it as
things were explained very well in that thread.

BTW I am much smarter now ;)

Robert
-- 
I always knew that one day Smalltalk would replace Java.
I just didn't know it would be called Ruby
-- Kent Beck