From: Rick DeNatale <rick.denatale@...>
Date: 2006-08-13T04:59:54+09:00
Subject: Re: String#split(/\s+/) vs. String#split(/(\s+)/)

On 8/12/06, Jan Svitok <jan.svitok@gmail.com> wrote:
> On 8/12/06, Eero Saynatkari <eero.saynatkari@kolumbus.fi> wrote:
> > Sam Kong wrote:
> > > Hello Rubyists,
> > >
> > > I'm reading Ruby Cookbook.
> > > The first chapter is about String.
> > > One of the examples shows the differenct between String#split(/\s+/) and
> > > String#split(/(\s+)/) without much explanation.
> > > I understand what sub-grouping is in regex.
> > > Bug I don't understand what role that plays in String#split.
> > >
> > > s = "one two  three"
> > >
> > > p s.split(/\s+/) #=> ["one", "two", "three"]
> > > p s.split(/(\s+)/) #=> ["one", " ", "two", "  ", "three"]
> >
> >  # Try this one
> >  p s.split /((((\s+))))/
> >
> > >
> > > Could anybody explain it, please?
> > >
> > > Thanks,
> > > Sam
>
> Seems like all groups in the separator regex are output to the result array.
>
> I wonder where is it documented, except for the source itself?
> (string.c, rb_str_split_m())

Well the pickaxe (2nd ed.) says so:

"If pattern is a Regexp, str is divided where the pattern matches.
Whenever the pattern matches a zero-length string, str is split into
individual characters. If pattern includes groups, these groups will
be included in the returned values."

Ruby-doc.org doesn't have that last sentence, in either the 1.8 nor
the 1.9 documentation.

-- 
Rick DeNatale
http://talklikeaduck.denhaven2.com