From: Austin Ziegler <austin@...>
Date: 2004-02-05T03:30:56+09:00
Subject: Re: RCR draft for enhanced "case..when..else..end" syntax

On Thu, 5 Feb 2004 03:00:04 +0900, Guoliang Cao wrote:
>>> What you've written here will do alternatives checks. Thus, if you
>>> have:
>>>
>>> a = "aaa"
>>> b = "BBB"
>>>
>>> then "Lowercase detected" will be printed. With "AAA" and "bbb",
>>> "Lowercase detected" will still be printed.
> I think this is very tricky. ',' equals to '||' here. This should be made
> very clear otherwise people should avoid use this form.

It's not tricky at all; it's consistent with the way that case..when..end 
works at all.

The form

  case
  when expr[, expr]+
  when expr[, expr]+
  else
  end

Is roughly equivalent to

  case true
  when expr[, expr]+
  when expr[, expr]+
  else
  end

In all cases, it's going to be cond === expr || cond === epxr2 (etc.), so 
that ',' is effectively an "or" condition in all case..when..end 
expressions. This is not a special case, so to speak.

-austin
--
austin ziegler    * austin@halostatue.ca * Toronto, ON, Canada
software designer * pragmatic programmer * 2004.02.04
                                         * 13.26.16