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<small><font face="Verdana">Hello Gustaf,<br>
</font></small><br>
<blockquote cite="mid:483FF46D.8080900@wu-wien.ac.at" type="cite">However,
can you tell more about your use-cases?
<br>
<br>
I was thinking a few times about providing interceptors
<br>
for single methods, similar to the method combinator :around
<br>
in CLOS.
<br>
</blockquote>
<br>
<small><font face="Verdana">When I read it right (I have little idea
about CLOS and not much experience with LISP...), this is exactly what
I mean. Just a piece of code that is called whenever a certain method
of an object is called and which can serve as kind of "observer" for
this method.<br>
<br>
One thing comes to mind since I play around with Tclhttpd and a
persistency framework: Tclhttpd maintains sessions as safe slave
interpreters. These interpreters must know about persistency objects in
the server, so it is necessary that <br>
- whenever a persistency object is created, a command alias for it must
be created in certain sessions (interpreters)<br>
- whenever a session is created, certain persistency objects must be
"informed" (-> a command alias for them must be created in the new
interpreter).<br>
- whenever a session is destroyed, it's alias must be removed from all
persistency objects that contain it.<br>
<br>
It involves interception of several methods and attributes, which I
currently do with instfilters and instfilterguards. But it would be
simpler if the filter is optionally just called on one method. I am
using different filters for different methods anyway, because it avoids
large [switch] statements.<br>
<br>
If that can be implemented with mixins, fine. I was seeing mixins more
in the context of code reuse as an alternative to inheritance, and not
as an interception technique.<br>
<br>
-- <br>
Eckhard<br>
<br>
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