Re: Broken threading [was: Unbelievable.]

[Tom Hardy <rhardy@mailandnews.com>]

In article <240720022348365027%planb@newsreaders.com>, 
"J.B. Moreno" <planb@newsreaders.com> writes:

> In article <m3fzy99j2f.fsf@defun.localdomain>,
>  Jesper Harder <harder@myrealbox.com> wrote:

>> Thomas Yan <tyan@twcny.rr.com> writes:
>> 
> -snip-
>> > You don't have a problem with some mail programs that see a
>> References > header, but don't know what it is and therefore stick
>> it in the reply?
>> 
>> Ah, I see.  I haven't encountered that problem.
>> 
>> So what you probably want is to check if the message-id in
>> In-Reply-To is equal to the last message-id in References -- and if
>> it isn't then use the one from In-Reply-To instead.

> That might work -- then again it might not.  I once did some local
> gatewaying in order to read a mailing list with a threaded view, and
> the only thing that was reliable was that programs repeated their
> mistakes.  You are describing a "generic" method, which did indeed
> work most of the time, but I had to have a whole bunch of special
> cases (it wouldn't surprise me to learn that some of them were
> developed by throwing darts to see what they should do),

I thought I would look at cases just for fun.  Tell me if I am all
wet or otherwise wasting my time.

   I.  Mailer updates References and In-Reply-To, in which case they
       both work, but references are more versatile.  In this case,
       In-Reply-To will be identical to the last reference.

  II.  Mailer does neither.  Anything goes, but it is likely to look
       like the first case.

 III.  Mailer updates In-Reply-To, ignores References.  In-Reply-To
       will not be found in References.

  IV.  Mailer updates References, ignores In-Reply-To.  In-Reply-To
       will be found in References, but it won't be the *last*
       reference.  (Does this happen?)

   V.  Other cases, such as one or the other header (or both) is
       missing.

In case V, you use what is available, including Subject, if
necessary.  You add/update References if posting, both headers if
mailing.  (Done, presumably)

In cases I-IV, you have both headers.  Check if In-Reply-To is found
anywhere in References.  If so, you can use References.  If
In-Reply-To != last reference, that only means In-Reply-To was not
updated.

Only in the case where In-Reply-To is not found anywhere in References
do you use In-Reply-To.  This is case III.  When posting, you could
slip In-Reply-To into References ahead of the Message-ID.

I suppose there is the case where In-Reply-To is ignored by dozens of
newsreaders and yet References get trimmed to the point where
In-Reply-To is no longer present.  Or a newsreader like AOL gives you
one reference, yet passes along an old In-Reply-To.  (Don't know.)

So I suppose I could modify the rule: If In-Reply-To is not found
anywhere in References and there are at least four (?) References, use
In-Reply-To.

Does that make sense?  Am I wasting my time? (Separate question, as I
may be going over old ground.)

-- 
    Tom Hardy   <*>
rhardy@mailandnews.com
   rhardy@visi.com