Re: leafnode 2 not creating "all_links" in gmane hierarchy.

On 2011-05-11, Matthias Andree wrote:

> Am 10.05.2011 14:45, schrieb Adam Funk:
>> On 2011-05-09, clemens fischer wrote:
>>> On Mon-2011/05/09-19:01 Christian Ebert wrote:

>>>> only_groups_pcre = PCRE
>>>>    This  parameter  lists  the  Perl-compatible regular
>>>>    expression of groups that are fetched or posted to this
>>>>    server. The PCRE is automatically anchored at the left hand
>>>>    side,  so  you  can omit the  leading  ^.  Remember  to
>>>>    escape dots, as in: de\.comp\.|de\.comm\. Another example
>>>>    might be only_groups_pcre=de\.(?!alt) that fetches all  de.*
>>>>    groups  that  are  not  de.alt.* groups. Consult the PCRE
>>>>    documentation for details.
>>>
>>> Oopsie.  I forgot about this.
>> 
>> Well, I put the caret in yesterday anyway.  It looks nice & my other
>> only_groups_pcre rules have it.
>
> It doesn't hurt if you do that.  But you need to pay some attention when
> using alternatives with the pipe ("|") character, since
>
> ^alt1|alt2
>
> would normally match alt2 anywhere in the word, not just at the beginning.
>
> ^(alt1|alt2) is what many people new to REs mean -- and to avoid such
> surprises, I'm anchoring the regexp.  De-anchoring can be specified by
> .*?, a non-greedy version of .*.

Interesting, thanks.

I'm not new to regexps, but I occasionally run into trouble because
(adapting a famous quote) the great thing about regexp languages is
that there are so many different ones on your computer as the same
time (grep, PCRE, s-lang, etc.).