From: Claus Spitzer <DocBoobenstein@...>
Date: 2004-05-19T13:40:16+09:00
Subject: Re: Zero is true ... whoda thunk?

Well, we're deving into semantics here, and I don't want to start a
flamewar but I certainly have to concur that milk.volume == 0 is not
the same as milk == 0. In other words, because _I_ don't have any milk
doesn't mean that the world has run out of milk. The milk in my fridge
is just an instance of the Milk class. Unlike the Matrix, we can't say
that "there is no Milk".
But let's take another example for zero -let f(x) = x^2 - 4. Now, when
x is 2 then f(x) is zero. Does that mean that f(x) is false too? No.
Before anyone starts to cry foul let me state the following: zero has
instances where it is not false, as shown above. It also has instances
where it could be considered false (albeit with warnings). Compare
that to "false" and "nil", which are false in every situation. The
latter are more consistent, don't you think?
 Cheers, 
    Claus


On Wed, 19 May 2004 12:53:56 +0900, David Naseby
<david.naseby@eonesolutions.com.au> wrote:
> 
> >-----Original Message-----
> >From: Hal Fulton [mailto:hal9000@hypermetrics.com]
> >>> if got_milk?  ... end
> >>>
> >>>where
> >>>
> >>> def got_milk?
> >>>   @milk_volume.zero?
> >>
> >>
> >> Bugger. I mean !@milk_volume.zero? of course.  So this whole
> >problem could
> >> be avoided by making 0==false, thus proving your point. THIS
> >is why I don't
> >> post normally....
> >
> >Haha... well, the got-milk logic would mean that negative numbers
> >would also be false, right? "I've got -5 gallons of milk. Give me
> >5 gallons, and I still won't have any!"
> >
> >Now you've got me thinking about the Mad Hatter's tea party...
> 
> You are just making the foolish mistake of assuming that just because my
> @milk_volume attribute responds to #zero? its a number, which, of course, in
> this mythical example, it isn't. It's a volume type (quart, in this case, as
> I'm speaking to old-fashioned types...), quite well defined, so when Rover
> checks if his milk volume, he finds out the answer in only ONE unit of
> measurement....
> 
> David.
> 
>