> Lett E S <eero.saynatkari / kolumbus.fi>
> Aihe: Re: regex questions
> 
> > Lett Jeff Davis <jdavis-list / empires.org>
> > Aihe: regex questions
> > 
> > In python the regexes allow you to call a function instead of just 
> > substitute the values (see <http://docs.python.org/lib/node111.html> for 
> > more details). That seems quite useful, is there something similar in ruby?
> > 
> > Also, let's say I want match anything between "a" and "b" unless it 
> > contains the word "foo". I could write two regexes like so:
> > 
> > if str =~ /a(.*)b/ and str !~ /a(.*foo.*)b/
> > 
> > Is there a good way to make that kind of logic into one regex? Is there 
> > some kind of "intersect" operator or a "not" operator?
> 
> There's /(?!foo)/x, but I can't think of any proper way to get it to 
> accept all other strings but the one specified. You could just 
> invert your problem and reject any strings that *do* have a 'foo' 
> between.
> 
> unless str =~ /a.*?foo.*?b/
> 
> If you need to, you can group to extract the non-foo part there.

That didn't come out right. What I meant to write is that if the above
match is not enough and you need to know that 'foo' is present, you
can simply do this:

str =~ /a.*?(foo).*?b/
fail if $1

> > Regards,
> >     Jeff Davis
> 
> E
> 
> 
>