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- To: common-lisp-object-system@SAIL.STANFORD.EDU
- Subject: with-added-methods
- From: Richard Mlynarik <MLY@AI.AI.MIT.EDU>
- Date: Thu, 26 May 88 13:58 EDT
[Apologies if I am rehashing an issue which has been previously discussed
-- the local CLOS archives are presently inaccessible.]
with-added-methods seems incompatible with the restriction (mentioned in
the doc for add-method) that a method can only be added to one generic
function at a time.
The doc for with-added-methods says:
Each generic function is created by adding the set of methods
specified by its method definitions to a copy of the lexically visible
generic function of the same name and its methods.
That for add-method says:
If the method object is a method object of another generic function,
an error is signaled.
I would think that the new generic function created by
with-added-methods must share all all the methods which were defined on
the original generic function.
I suppose that an alternate reading of the first piece of documentation
is ``to a copy of the lexically visible generic function of the same
name and TO A COPY OF its methods'' -- I'd like to think that this isn't
what was intended, since it would seem to introduce far more problems
than it solves.
Some passing remarks about with-added-methods:
* Does it really need to be a special form rather than a macro?
I -believe- I could define it in terms of generic-flet -- however,'
I haven't thought this through very thoroughly.
* Is there sufficient Chapter 3 support to enable this kind of thing to
be `portably' implemented? Apart from the above-mentioned lossage
involving methods added to more than one generic function, there are
problems brushed under the rug by ``A COPY OF the lexically
visible generic function.'' Presumably there needs to be some
cloning method for generic functions.
* I guess I'll never actually use with-added-methods in any case
because of inefficiencies due what I perceive as the fatal problem