From: Charles Comstock <cc1@...>
Date: 2004-07-08T05:52:34+09:00
Subject: Re: Class#=== has interesting results

On Thu, 8 Jul 2004, David A. Black wrote:

> Hi --
>
> On Thu, 8 Jul 2004, Charles Comstock wrote:
>
> > Mauricio Fern�ndez wrote:
> >
> > > On Wed, Jul 07, 2004 at 04:22:36PM +0900, Charles Comstock wrote:
> > >
> > >>Why does this happen?
> > >>
> > >>class A
> > >>end
> > >>
> > >>A == A		#1 => true
> > >>A === A		#2 => false
> > >>
> > >>But 2 doesn't make any sense to me, why doesn't an A match another A?
> > >>Is this just something that slipped through or is there a specific
> > >>reason for this?
> > >
> > >
> > > A is not an instance of A; see the ri info for Module#===.
> > >
> >
> > At what point does it cause trouble for it to also return true if the
> > class matches?
>
> At the point where you call it :-) It can't do both; there would be no
> way to interpret the result:
>
>   case s
>     when String ...  # what do you do here? print it? instantiate it?
>

Sorry perhaps I didn't word my question well.  I meant when does it cause a
problem for a class x to match itself?  What code fails if A === A results in
true?  Why would you ever want to match the descendents and instances of A but
not match A itself.

Charles Comstock