From: Austin Ziegler <austin@...>
Date: 2004-02-05T03:43:12+09:00
Subject: Re: RCR draft for enhanced "case..when..else..end" syntax

On Wed, 4 Feb 2004 12:55:42 -0500, Guoliang Cao wrote:
>> better yet with a lookup table. This sort of problem is handled easily
>> by intelligent data-driven design.
> Don't mix system design with language capabilities please.

I'm not. This proposal does. What you're wanting to do is effectively make
it so that case operates in parallel on multiple conditions. I can count on
zero hands the number of times that I've needed this capability. I have
found it more useful to worry about my data design and make sure that I
have a proper lookup table. Robert's design does exactly that with multiple
custom objects instead of a lookup table.

> I think it's not a bad thing to let "case" to take more than one
> expressions. Just like a function can take any number of arguments. Why
> does "case" have to be limited to zero or one? Because all our languages
> are designed this way? (AFAIK only Ruby "case" can take 0 expressions.
> That's some good stuff introduced by Ruby, right? So why not go one step
> further?) Or because it's impossible?

Nothing is impossible. It's a question as to whether it's a good idea.
Frankly, your proposal is a bad idea. I said as much to your initial posting
on RubyGarden.

>> There is no need for a new or modified language construct here.
> Since 2.0 is a major update to 1.x, why can't we introduce new language
> constructs if they really makes sense?

Except that your construct doesn't make sense.

1. It introduces unnecessary complexity.
2. It adds a lot of "magic" that isn't clear (_ or ~ -- both are really
   ugly). Ruby2 seems to be getting rid of a lot of that silly magic.
3. It adds a language "feature" that is better handled by proper program
   design.

-austin
--
austin ziegler    * austin@halostatue.ca * Toronto, ON, Canada
software designer * pragmatic programmer * 2004.02.04
* 13.31.26