From: Ben Giddings <ben@...>
Date: 2003-07-15T07:17:41+09:00
Subject: Re: Booleans

On Mon July 14 2003 5:17 pm, Austin Ziegler wrote:
> On Tue, 15 Jul 2003 05:34:02 +0900, Mark J. Reed wrote:
> > I would also be happy if the test for falseness was less simplistic 
> > than "false is false, nil is false, everything else is true".  I am 
> > constantly being bitten by the fact that 0 is true.
> 
> If you *know* that you will be getting a Fixnum in response, you can use
> Fixnum#nonzero? and Fixnum#zero? to get the tests that you're after.

I don't think the issue is that it is difficult to come up with a test to 
determine whether or not a number is zero or nonzero, it's just whether 
Ruby's treatment of "false" and "nil" as false and 0 and the empty string as 
true makes sense, or if it should maybe be more flexible.

I happen to like 0 and "" being logically "true".  It sometimes requires extra 
typing but that's fine.  It's very lisp-ey in that only nil is false, 
everything else is true, only Ruby does have boolean classes, and in that 
case the literal "false" should of course be false.

While I also kind-of like the idea of a "to_b" method that can determine if a 
class is logically false, I see it causing lots of problems.  If that were 
possible, someone might take advantage of Ruby's flexibility to make 0.to_b 
be false for their program.  This could lead to some real difficulty in 
understanding or running other people's code.

I prefer to be overly anal about the whole thing and always just say:
if 0 != retval ...

Ben