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.
--
Luís Oliveira
http://student.dei.uc.pt/~lmoliv/
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