From: Mark Hubbart <discordantus@...>
Date: 2004-11-12T04:11:40+09:00
Subject: Re: #scan with or'd (`|`) subexpressions.

On Fri, 12 Nov 2004 01:52:00 +0900, Yukihiro Matsumoto
<matz@ruby-lang.org> wrote:
> Hi,
> 
> In message "Re: #scan with or'd (`|`) subexpressions."
>     on Thu, 11 Nov 2004 23:29:58 +0900, "trans.  (T. Onoma)" <transami@runbox.com> writes:
> 
> |Does the new Ruby regexp engine do this?
> 
> 
> |
> |  irb(main):001:0> '1234'.scan(/(1)(2)|(3)(4)/)
> |  => [["1", "2", nil, nil], [nil, nil, "3", "4"]]
> |  irb(main):002:0>
> |
> |Why would all the subexpressions be listed when there is an `|` (or) used? I
> |expected:
> |
> |  => [["1", "2"], ["3", "4"]]
> 
> You will never know which subexpression is matched, if you get your
> expected result.  Is there any reason /(1|3)(2|4)/ is not sufficient?

This reminds me... when will Ruby support named subexpressions?
Oniguruma fully supports them now; but there doesn't appear to be a
way to access this in the ruby code.

thanks,
Mark