Re: Moving & suppressing

[Greg Stark <gsstark@MIT.EDU>]

> I've also added support for suppressing duplicate articles.  This is
> (kinda) poor man's, uhm, woperdaughter's, Xref support -- Gnus keeps a
> list (and hashtb) of all Message-ID's that have been (marked as) read.
> The next time Gnus sees a message with the same Message-ID, it will
> mark it as read.  There's also an option for saving this list to a
> file, but that's optional.

While trying to evangalize a bit someone asked if Gnus could prevent them from
seeing the same e-mail message twice even if the message-id's weren't
available. 

This would be possible if we hashed the entire article, or even just the
length and the first block of the article and saved that as a kind of
pseudo-message-id. This really would be pretty nice, even i often see the same
mail message on multiple lists that i read via mail archives, and often these
archives don't retain the message-id's (i disagree with that as well of
course, but Gnus should be general enough to not assume all the backends are
news or mail. Some backends won't have any concept of message-id.)

This would be a moderately expensive operation, especially if we tried to do
it at summary buffer generation time, but it would be nicer if we tried to do
it just before showing an article, then if it was one we've already seen it
could magically become marked as a duplicate and we could go on to the next
article. That way we don't need to actually load the article until we would
have to anyways.

greg