GNU Info

(gnus)Topic Parameters

---

Prev: Topic Topology Up: Group Topics

---

Enter node , (file) or (file)node

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.