Re: How to open a summary buffer reliable?

[David Engster <deng@randomsample.de>]

Tassilo Horn <tassilo@member.fsf.org> writes:
>>> If you rescan the group before entering, Gnus should notice that the
>>> article got deleted. You can do this by using gnus-activate-group
>>> with `scan' being non-nil.
>>
>> Hey, that seems to work!
>
> I was a bit too quick.  It does work for nnimap groups, but I get an
> error for nnml groups.
[...]
> Doing things manually after (gnus-activate-group "nnml+Foo:bar" t) a
> `C-u 1 RET' won't enter that group, too.  So I guess the error comes
> from the fact that the group's summary wasn't created.
> So is that a bug in nnml or is it correct that only nnimap supports it?

I guess the beloved gnus-fixup-nnimap-unread-after-getting-new-news
makes this work with nnimap, but not with nnml. I don't know how other
back ends behave in this regard.

> Ideally I'd love to see that work for all backends supporting deletion.

This is all related to Gnus not knowing the actual article numbers. We
discussed how this could be solved in August, based on Vitaly
Mayatskikh's patches. Unfortunately, I didn't have time since then to
work on this...

nnml is tricky since it tries to avoid rebuilding the active
information, this is why it usually recognizes this situation only after
restarting Gnus. You can force rebuilding the active file by using
nnml-generate-nov-databases-directory (which can be costly for large
groups). This function expects a directory, not the group name, so you
would have to extract that first. And then you would have to put this
information in gnus-active-hashtb, maybe also in the cache via
gnus-cache-possibly-update-active (maybe they're the same, I don't
really know).

Looks like work; maybe someone else knows how to do this easier?

-David