Path: utzoo!attcan!uunet!snorkelwacker!ira.uka.de!smurf!urlichs
From: urlichs@smurf.sub.org (Matthias Urlichs)
Newsgroups: comp.lang.perl
Subject: Re: This looks like a job for Perl Man (NNTP)
Message-ID: <m3ppf2.p43@smurf.sub.org>
Date: 27 Sep 90 08:25:18 GMT
References: <20550@orstcs.CS.ORST.EDU> <18409:Sep2703:08:1290@kramden.acf.nyu.edu> <9695@jpl-devvax.JPL.NASA.GOV>
Organization: University of Karlsruhe, FRG
Lines: 39

In comp.lang.perl, article <9695@jpl-devvax.JPL.NASA.GOV>,
  lwall@jpl-devvax.JPL.NASA.GOV (Larry Wall) writes:
< : 
< : Because certain people don't believe in accurate min article fields,
< : it's safer to convert the unread articles.
< 
< Might be faster too, depending on how many unread newsgroups you keep in
< your .newsrc.
< 
< The only problem I see with doing the unreads is that you would end up
< marking as read any articles that happened to be on the new server but
< not on the old, unless you constructed the universal set on the old server
< (which is certainly doable, but a drag).
< 
Another problem is that nobody guarantees that the articles on both servers
are in the same order. So I'd do something like this, assuming that the NNTP
servers understand XHDR (most do):

for each group
   read numbers of known articles
   old:GROUP <group>
   old:XHDR Message-ID 1-9999999
     remember the ID of every read article
   forget list of numbers -- not applicable to new server
   new:GROUP <group>
   new:XHDR Message-ID 1-9999999
     remember the number of every known ID
     remember which articles are not present
   construct read-messages list by concatenating the ranges of
     remembered numbers; don't forget to omit the range
     from last_article+1 to 9999999 :-)

That would probably do it. Anyone want to code it in Perl?
Concatenating the number ranges into a reasonable newsrc line doesn't look
particularly easy, although Randal will surely invent a good one-liner for
it. ;-)
-- 
Matthias Urlichs -- urlichs@smurf.sub.org -- urlichs@smurf.ira.uka.de     /(o\
Humboldtstrasse 7 - 7500 Karlsruhe 1 - FRG -- +49+721+621127(0700-2330)   \o)/