From: Robert Klemme <shortcutter@...>
Date: 2007-07-13T17:21:50+09:00
Subject: Re: Regexp Question - Merb::Router

2007/7/13, Daniel N <has.sox@gmail.com>:
> On 7/13/07, Robert Klemme <shortcutter@googlemail.com> wrote:
> >
> > 2007/7/13, Daniel N <has.sox@gmail.com>:
> > > Hi,
> > >
> > > I'm looking through the Merb::Routing code and I've found a regexp that
> > I
> > > can't figure out how it works.
> > >
> > > Merb::Router::SECTION_REGEXP  #=> /(?::([a-z*_]+))/
> > >
> > > It takes a route definition string, like "/products/:model/:id"  and
> > > extracts the "model" string on the first pass, and later  the "id"
> > string.
> > >
> > > Can anyone shed some light on what the
> > > ?::
> > > part does?  I haven't found it in any of the documentation for Ruby
> > Regexps
> > > that I've found.
> >
> > It's actually *two* parts: (?:) is a non capturing regexp group.  The
> > second ":" literally matches a single colon.
> >
> > Kind regards
> >
> > robert
> >
> > Thanx Robert,
>
> I've not heard of that before.  Makes searching on google much easier :)
>
> /(?::([a-z*_]+))/
>
> I guess this means that a nested group within this non capturing group (this
> case) is captured though since the $1 variable is refered to later.

Exactly.  Btw, in your case I'd probably use another regexp. Some samples:

irb(main):001:0> "/products/:model/:id".scan %r{/:([^/]+)}
=> [["model"], ["id"]]
irb(main):002:0> "/products/:model/:id".scan %r{:([^/]+)}
=> [["model"], ["id"]]
irb(main):004:0> "/products/:model/:id".scan %r{:[^/:]+}
=> [":model", ":id"]

But of course I do not know the full spec of your input data.

Kind regards

robert