From: Gary Wright <gwtmp01@...>
Date: 2007-04-14T03:30:47+09:00
Subject: Re: Question about Fixnum


On Apr 13, 2007, at 1:36 PM, Tim Pease wrote:
> Fixnum objects are immediate objects in the Ruy source code (other
> immediate objects are nil, true, false, and symbols). These immediate
> objects occupy 4 bytes of storage (unsigned long) on most machines.
> They are accessed by casting and bit shifting in the Ruby source code.

As long as you think of this description ('immediate objects') as
entirely an implementation issue, I think it is useful.  When you
switch to talking about Ruby language semantics, I think it is
better to simply think of Fixnum objects and references as the same
as all other Ruby objects and references. Same for NilClass,
FalseClass, and TrueClass. The differences are that the language
provides literal representations of these references
(-1,0,1,nil,false,true) and also ensures that object identity and
object equivalence are the same for their respective classes (for
example, #dup has no meaning for these objects and you can't create
new instances of NilClass, FalseClass, and TrueClass).

Gary Wright