Re: String#upto edge case - empty string causes infinite loop

On 1/11/07, Berger, Daniel <[e-mail]> wrote:
> > -----Original Message-----
> > From: Arnaud Bergeron [mailto:[e-mail]]
> > Sent: Wednesday, January 10, 2007 9:20 PM
> > To: [e-mail]
> > Subject: Re: String#upto edge case - empty string causes infinite loop
>
> <snip>
>
> > > I understand your point, but I could just as well argue
> > that there is
> > > no logical successor to an empty string, and therefore it's
> > a special
> > > case. Another point to consider is that, if we have "".succ return
> > > "0", we get this result from String#upto:
> >
> > I think you missunderstood something.  I don't propose it
> > returns "0" but "\000" which the character with ASCII value 0
> > (i.e. NUL).  I agree it could be some other value, but why I
> > chose this one is because that is the string with the
> > "smallest" (as determined by <) value which is bigger than "".
>
> Hm, I guess if I think about it as null rather than 0 it makes more
> sense.
>
> > > "".upto(2) => ["", "0", "1", "2"]
> > >
> > > Either approach feels more or less arbitrary. I vote to err on the
> > > side of caution and stick with my original patch. :)
> >
> > I think this issue might not be as important as I let it show
> > because this is not common code.  I still feel that ("" <
> > "".succ) == false is wrong though.
> >
> > However, if succ is not going to change, then it's better to
> > have your patch than nothing.
> >
> > Last but not the least.  I realize I have not provided a
> > patch for my solution.  Well here it is:
> >
> > --- string.c.orig     Wed Jan 10 22:52:14 2007
> > +++ string.c  Wed Jan 10 23:18:12 2007
> > @@ -1392,7 +1392,6 @@
> >
> >      str = rb_str_new5(orig, RSTRING(orig)->ptr, RSTRING(orig)->len);
> >      OBJ_INFECT(str, orig);
> > -    if (RSTRING(str)->len == 0) return str;
> >
> >      sbeg = RSTRING(str)->ptr; s = sbeg + RSTRING(str)->len - 1;
>
> I guess either one works for me. I leave it to Matz to decide which he
> prefers.

I'm fine with that.

> Regards,
>
> Dan
>
>
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