[armedbear-devel] CLOS / D-M-C tests failure DMC-TEST-MC.1 help requested

Erik Huelsmann ehuels at gmail.com
Tue Aug 7 19:59:05 UTC 2012

On Tue, Aug 7, 2012 at 9:09 PM, Erik Huelsmann <ehuels at gmail.com> wrote:

> > What happens is that the second form expands into:
>> >
>> >                            :LAMBDA-LIST
>> >                            '(X &OPTIONAL B)
>> >                            :METHOD-COMBINATION
>> >                            '(DMC-TEST-ARGS-WITH-OPTIONAL.4))
>> >                         (X &OPTIONAL B)
>> >                         (PROGN X B))
>> >
>> > Because the macro expander continues to expand the forms before
>> compiling them, it'll expand the DEFMETHOD above. When the DEFMETHOD gets
>> expanded however, it's expansion is dependent on the existence of the
>> generic function. However, since the form as a whole hasn't been
>> interpreted yet, there *is* no generic function: after all, that's being
>> created in the first form of the PROG1.
>> >
>> > Something similar probably happens during compilation.
>> >
>> >
>> > I'm now wondering what the next step should be to resolve this
>> situation...
>> >
>> >
>> > Ah. Going back 10 months and looking at the DEFMETHOD macro there, I
>> see now what the difference is between then and now: back then we didn't
>> depend on the GF existing during the macro expansion. Now we do. Can we
>> generate a different macroexpansion which defers the GF-being-defined
>> requirement to evaluation time?
>> Cute.  I think we can beef up %defgeneric to accept a list of method
>> descriptions and the macro environment (for make-method-lambda) and call
>> ensure-method inside %defgeneric, after creating the generic function.  I
>> can have a look at that.
> I can see how doing that would work at run-time, ie where %defgeneric
> would be called without the image having been exited (simply grab the
> environment and tuck it in a closure, or even simply stick it in the
> expansion). However, how do you expect to do the same at file-compilation
> time where the %defgeneric gets called after the image (possibly) has been
> closed and cleanly started up?

Reading this quote:

*Note:* The body of methods can also appear in the *:initial-methods* option
of *defgeneric* forms. Initial methods are not considered by any of the
protocols specified in this document.

from http://www.alu.org/mop/concepts.html

leaves me wondering if we're too strict to apply the requirement to use
DEFMETHOD and MAKE-METHOD-LAMBDA processing the way we do now. Does this
provide a way out?


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