From: Matthew Kerwin <matthew@...>
Date: 2012-07-20T13:17:15+09:00
Subject: Re: unless if not == unless post_on_ruby_forum

It's most useful for perl-esque one-liners:

  die unless it_worked

On 20 July 2012 14:05, roob noob <lists@ruby-forum.com> wrote:
> So everything I have thus far read and heard about the Ruby unless
> keyword lead me to believe that it is just another word for if not. This
> is not true.
>
>  unless 1 + 1 == 2
>    puts "a"
>  elsif 1 + 1 == 5
>    puts "b"
>  else
>    puts "c"
>  end
>
> this code fails and complains that it expects an end to be where elsif
> is
> however
>
>  if not 1 + 1 == 2
>    puts "a"
>  elsif 1 + 1 == 5
>    puts "b"
>  else
>    puts "c"
>  end
>
> works as expected. This took me quite a while to figure out as everyone
> had always lead me to believe that unless is just the cool kids way of
> saying if not in ruby.
>
> So I guess my question is, are there any other unexpected behaviors of
> unless that I should know about? I think I might just start using if not
> and ignoring unless, I actually end up having to translate it to if not
> in my head anyway to read things clearly, and it doesn't work with
> elsif. Why does everyone rave about how unless is exactly like if not
> but with clearer language, if this is not the case ?
>
> --
> Posted via http://www.ruby-forum.com/.
>



-- 
  Matthew Kerwin, B.Sc (CompSci) (Hons)
  http://matthew.kerwin.net.au/
  ABN: 59-013-727-651

  "You'll never find a programming language that frees
  you from the burden of clarifying your ideas." - xkcd