From: Phrogz <phrogz@...>
Date: 2007-12-14T04:05:01+09:00
Subject: Re: Regexp Matching Not Blank And Not A Specific Word?

On Dec 13, 11:47 am, Sebastian Hungerecker <sep...@googlemail.com>
wrote:
> Andrew Stewart wrote:
> > In fact I'm beginning to doubt
> > that (?!re) works at all on my system (Ruby 1.8.6)...but on balance
> > it's probably me rather than my Ruby installation!
>
> It's not you. The ruby 1.8 regexen don't support negative lookahead. You'll
> get that in ruby 1.9 or by installing and using the oniguruma regexp-engine
> instead of the default ruby 1.8 one.

Not true:
C:\>ruby -v
ruby 1.8.6 (2007-03-13 patchlevel 0) [i386-mswin32]

C:\>irb
irb(main):001:0> s = "hello world"
=> "hello world"
irb(main):002:0> s.scan /[eo]./
=> ["el", "o ", "or"]
irb(main):003:0> s.scan /[eo](?!r)./
=> ["el", "o "]

It just doesn't support negative or positive *lookbehinds*.