Topic Parameters
----------------
All groups in a topic will inherit group parameters from the parent
(and ancestor) topic parameters. All valid group parameters are valid
topic parameters (Note:Group Parameters).
In addition, the following parameters are only valid as topic
parameters:
`subscribe'
When subscribing new groups by topic (Note:Subscription
Methods), the `subscribe' topic parameter says what groups go in
what topic. Its value should be a regexp to match the groups that
should go in that topic.
Group parameters (of course) override topic parameters, and topic
parameters in sub-topics override topic parameters in super-topics. You
know. Normal inheritance rules. ("Rules" is here a noun, not a verb,
although you may feel free to disagree with me here.)
Gnus
Emacs
3: comp.emacs
2: alt.religion.emacs
452: alt.sex.emacs
Relief
452: alt.sex.emacs
0: comp.talk.emacs.recovery
Misc
8: comp.binaries.fractals
13: comp.sources.unix
452: alt.sex.emacs
The `Emacs' topic has the topic parameter `(score-file .
"emacs.SCORE")'; the `Relief' topic has the topic parameter
`(score-file . "relief.SCORE")'; and the `Misc' topic has the topic
parameter `(score-file . "emacs.SCORE")'. In addition,
`alt.religion.emacs' has the group parameter `(score-file .
"religion.SCORE")'.
Now, when you enter `alt.sex.emacs' in the `Relief' topic, you will
get the `relief.SCORE' home score file. If you enter the same group in
the `Emacs' topic, you'll get the `emacs.SCORE' home score file. If
you enter the group `alt.religion.emacs', you'll get the
`religion.SCORE' home score file.
This seems rather simple and self-evident, doesn't it? Well, yes.
But there are some problems, especially with the `total-expiry'
parameter. Say you have a mail group in two topics; one with
`total-expiry' and one without. What happens when you do `M-x
gnus-expire-all-expirable-groups'? Gnus has no way of telling which one
of these topics you mean to expire articles from, so anything may
happen. In fact, I hereby declare that it is "undefined" what happens.
You just have to be careful if you do stuff like that.