From: Robert Klemme <bob.news@...>
Date: 2004-12-09T22:52:28+09:00
Subject: Re: [rcr] String#split behaves odd


"Brian Schr�der" <ruby@brian-schroeder.de> schrieb im Newsbeitrag
news:20041209143808.412a5f7e@black.wg...
> On Thu, 9 Dec 2004 22:19:55 +0900
> Glenn Parker <glenn.parker@comcast.net> wrote:
>
> > trans. (T. Onoma) wrote:
> > > On Wednesday 08 December 2004 10:00 am, Florian Frank wrote:
> > > |
> > > | "abc\n\ndef\nghi".split(/\n+/)
> > >
> > > Sorry, what are you pointing out here?
> >
> > It is impossible to have perfect forwards-backwards symmetry with
split
> > and join.  When the split pattern matches more than one possible
string
> > of characters, there is no way to join the results of the split and
> > recover the original input.
> >
>
> That is obvious, but no argument against wanting split and join to be
symmetric
> for fixed split patterns. (On the other hand one could even argue, that
we
> "need" variable join patterns to make it symmetric again. ;)

Just one note: you can use regexp grouping to get the delimiters as well
as the content.  That way you can join with "" and get the original back:

>> "abababab".split(/b/)
=> ["a", "a", "a", "a"]
>> "abababab".split(/(b)/)
=> ["a", "b", "a", "b", "a", "b", "a", "b"]

There might be certain border cases though.

Kind regards

    robert