From: Matthew Moss <matthew.moss.coder@...>
Date: 2006-02-09T01:16:26+09:00
Subject: Re: boolean annoyance

> there is one thing in ruby that annoys me most (at least for now).
>
> if 0
>         puts "true"
> end
>
> Yes, I know everything expect nil and false are true but that's probably
> the most illogic part of ruby.

It's actually the most illogic part of languages like C that treat 0
as false.  Believe me, having spent most of my programming life using
C/C++ and being used to that, I make mistakes regularly whilst writing
Ruby code.

0 is an integer and quite often a valid value. C's treatment of 0 as
false is convenient in some situations but horribly inconvenient in
others.  Because if I'm expecting an integer and zero is a legal
value, then you have to start playing around in your conditionals... 
"Okay, today any -1 is false"...  or even at different levels than
that.  Part of the problem is that C doesn't have an actual NULL... 
NULL is just defined as zero.  Overlap, explosions, crash and burn...


> Because of this stuff like
>
> if flags & 0x01
>         # do some stuff if flag is set
> end

There are alternatives....  In C/C++, this is what I would do because
it is convenient.  In Ruby, I might do:

if (flags & 0x01).nonzero?

Course, I probably wouldn't hardcode 0x01 in any language, so:

if (flags & kSomethingEnabled).nonzero?

But I'd even go a bit further (and often do this in C++ for clarity):

def something_enabled?
  (flags & kSomethingEnabled).nonzero?
end

if something_enabled?
  # do something
end

Or even (in Ruby w/ symbols):

mask = { :something => 0x01 }
def enabled? feature
  (flags & mask[feature]).nonzero?
end

if enabled?(:something)
  # do something
end


You could even go so far to package this into a bitfield class (if
there isn't one already).
Point is, there are lots of better ways to get what you need done
without sacrificing the value 0 to the old-skool gods. (Who I get
along with just fine usually, but not with Ruby's zero.)