From: Bill Davidsen (davidsen@prodigy.com)
Date: Fri Feb 01 2002 - 08:46:09 CST
On Thu, 31 Jan 2002, Charles Lindsey wrote:
> Currently, our draft allows
> Distribution: foo, !bar, baz
> with the semantics that the article is rejected unless the agent has
> been configured to send/accept at least one of the +ve distrubutions
> and none of the -ve ones (so Distribution: foo, !foo would be rejected
> everywhere).
And justly so ;-)
> Note that the mechanism which an agent uses to configure itself are none
> of our business, but in practice the config would likely use wildmats of
> the form "all,!foo". I think INN may be like that, and certainly CNews
> has something of that sort.
>
> Also, in checkgroups nessages, our draft allows a chkscope parameter of the form
> Control: checkgroups de, !de.binaries
> whose semantics are not entirely clear (I used de.* as an example
> because I seem to remember that there is a case in that hierarchy
> that caused us to insert the `!` feature, but I do not recall the
> precise details). Anyway, it is not clear what would be the meaning of
> "de, !de", or whether "!de.binaries, de" would have meant something
> different.
I don't see that "de, !de" differs from your "foo,!foo" above. But to be
useful the list MUST be parsed left to right. Therefore:
de,!de.sex,de.sex.mod all of de, except de.sex and including de.sex.mod
!de.binaries,de I would suspect this means all of de, at
least to me.
> Also, in the latest NNTP draft, there is provision for wildmats such as
> de.*,!de.binaries.*
> where, after much discussion, we arrived at the rule:
> "start from the right hand end and find the first wildmat component
> that matches the target. If it is a negative component, the match
> fails; if it is positive the match succeeds."
This seems to preclude my example above, and I don't believe that's
intended behaviour, is it? It would prevent rules like "all this
hierarchy except this branch but including this twig on that branch"
which are real-life useful.
> That semantics is absolutely clear and, since that rule will be built
> into much server software, I think the chkscope should be interpreted in
> the same way (though I am not suggesting that its syntax should go so
> far as to include wildmat-like wild cards).
I don't see the semantics of "start at the left, apply each portion, if
it applies set the pass/fail state." The rules you cite for negative
match are more like the "@" operation in INN, which means "fail this no
matter what else it matches." I don't think we want ! to mean and
absolute fail, do we? It precludes useful things.
-- -bill davidsen (davidsen@prodigy.com) "The secret to procrastination is to put things off until the last possible moment - but no longer" -me