Hi Maxime, Well, these particular examples aren't valid since GOOPS doesn't allow type specifiers for keyword arguments. (It's the same in CLOS.) Type dispatch is done *only* on the required arguments.
Best regards, Mikael On Sat, Nov 23, 2024 at 4:31 PM Maxime Devos <maximede...@telenet.be> wrote: > >Any opinions on what is best: Having a define-method* or having the > functionality in define-method itself? > > > > You can’t unify define-method with define-method* without making some > arbitrary choices in some special cases (the same applies to define-method* > too actually, and also to define-method on its own without keyword > arguments, but it needs to be considered and documented somewhere). > > > > Consider (please ignore syntax errors, don’t have much practice with > GOOPS): > > > > (define-method (f (a <keyword>) (b <integer>)) > (pk 'positional a b)) > > > > ;; what I mean is to only consider ‘foo’ that are of class <number>, I > don’t mean <number> as default value > > (define-method (f (#:key foo <number>)) > (pk 'keyword foo)) > > > > An ambiguous case: (f #:foo 1). This matches both the first and second > implementation. <integer> is more specific that <number>, so this sounds > like the first method should win. But, ‘#:foo’ is more specific than > <keyword>, so the second should win. > > > > I don’t know what the rule is for positional arguments (I assume earlier > arguments are more important in case of ambiguity?). However, the same rule > cannot be applied to keyword arguments, since they aren’t positional. > Consider: > > > > (define-method (g (#:key foo <integer>) (#:key bar <object>)) > > (pk 'integer foo)) > > > > (define-method (g (#:key bar <symbol>) (#:key foo <object>)) > > (pk 'symbol bar)) > > > > (g #:foo 1 #:bar a) ;integer or symbol? > > (g #:bar a #:foo 1) ;does this produce the same result? > > > > Either ‘integer’ or ‘symbol’ would be appropriate, but it shouldn’t depend > on whether #:foo or #:bar is written first in the argument call. Now #:foo > and #:bar need to be (ideally deterministically) ordered, but any > particular ordering is somewhat arbitrary, and it’s a bit against the > notion of keyword arguments – orderings are more a thing for _*positional*_ > arguments. > > > > Potential escape: in case of ambiguity, give up and throw some kind of > exception. Not ideal, but at least it’s not random, doesn’t depend on how > the keyword arguments were worded, and it would be limited to keyword > methods. > > > > Best regards, > > Maime Devos >
