[Python-Dev] Behavior of matching backreferences
Gustavo Niemeyer
niemeyer@conectiva.com
Sun, 23 Jun 2002 20:30:06 -0300
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
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