Hello,
There are a couple of features people need -- namely stdcall and dll namespaces -- that depend on the ability to pass options to defcfun, foreign-funcall and defcallback. So we need to agree on a proper syntax to do this. Bonus points if we can get backwards compatibility.
This has been discussed in the past regarding defcfun but I forget what the conclusions were. Anyway, starting with the easiest:
(defcallback (foo :opt1 ... :opt2 ...) :rettype ((arg1 :type1) ...) body)
That seems to be the obvious place to put the options for defcallback. Any objections? defcfun, however, has some more possibilities:
;; #1 -- backwards compatible, similar to defcallback (defcfun (foo :opt1 ... :opt2 ...) :rettype (arg1 :type1) (arg2 :type2))
;; #2 -- backwards compatible, slightly funky syntax IMHO (defcfun foo :rettype (arg1 :type1) (arg2 :type2) :opt1 ... :opt2 ...)
;; #3 -- not backwards compatible, indentation looks odd when ;; there are no options present (defcfun foo :rettype ((arg1 :type1) (arg2 :type2)) :opt1 ... :opt2 ...)
IIRC, I used to be prefer option #3 because that way we could cleanly define the keyword arguments in the defcfun macro but lately I'm more inclined towards #1 since it indents better and the syntax is similar to defcallback. Also, #1 is backwards compatible; that's a plus, I guess. I think James used to prefer option #2. Is that still true? I don't completely dislike option #2.
And finally there's foreign-funcall. The syntax here should be pretty obvious too:
(foreign-funcall ("foo" :opt1 ... :opt2 ...) :type1 arg1 :type2 arg2 :rettype)
Except foreign-funcall also accepts a pointer, and in that case the first argument is evaluated (unlike the case where the argument is a string). I think (foreign-funcall ((some-form ...) :opt1 ... :opt2 ...) :type1 arg1 ... :rettype) looks a bit odd. Does that justify splitting such functionality off to another macro foreign-funcall-pointer with a different syntax? I think I'd rather avoid that.
Oh, and we need options for define-foreign-library too. Once again I'm thinking we should place the options in the name argument: (define-foreign-library (name :opt1 ... :opt2 ...) ...).
Comments and suggestions are most welcome.