Hello Tim!
Wow, yesterday's drugs haven't worn off yet <wink>. The details of this explanation were partly full of beans. Let's consider a different regexp: [...]
Thanks for explaining again, in a way I could understand. :-)
^(a)?b\1$
Should that match
b
or not? Python and Perl say "no" today, because \1 refers to a group that didn't match. Ir remains unclear to me whether Gustavo is saying it should, but, if he is, that's too big a change, and
^(a?)b\1$
[...] I still think it should, because otherwise the "^(a)?b\1$" can never be used, and this expression will become "^((a)?)b\1$" if more than one character is needed. But since nobody agrees with me, and both languages are doing it that way, I give up. :-) Could you please reject the patch at SF? Thank you! -- Gustavo Niemeyer [ 2AAC 7928 0FBF 0299 5EB5 60E2 2253 B29A 6664 3A0C ]