[resending directly as it seems messages posted through Gmane don't
make it to the list :-/ ]
>>>>> "Luís" == Luís Oliveira <[EMAIL PROTECTED]>:
Luís> "Hoehle, Joerg-Cyril" <[EMAIL PROTECTED]> writes:
>> In CLISP, every closure can be turned into a callback, and this is
>> valuable since it allows to retrieve context information out of the
>> closure. Is cffi's limitation caused by some implementations?
Luís> To my knowledge, yes. AFAICT, only SBCL/x86 and CLISP support
Luís> that.
Luís> Regarding the behaviour of CFFI:DEFCALLBACK as a non-toplevel
Luís> form, not only will it set it globally, the callback itself won't
Luís> be generated at runtime on most Lisp, IIRC.
I've just ran into the same problem. I really really need closures as
callbacks. I've tried the naive approach:
(defmacro object-event-callback-add (obj type function)
`(foreign-funcall "evas_object_event_callback_add"
:pointer ,obj
callback-type ,(foreign-enum-value 'callback-type type)
:pointer (get-callback (defcallback ,(gensym "CB")
:void
((data :pointer) (cb-e evas) (cb-obj object)
(cb-event :pointer))
(funcall ,function cb-e cb-obj cb-event)))
:pointer (null-pointer)))
... but that's a half-baked solution with too many limitations and only
works in a simple example that you run once.
What are the problems with unnamed callbacks? My guess was that they
will never get garbage-collected, but how about storing all of these in
a table somewhere and explicitly freeing them after they are no longer
needed? In my case I do have a way of finding out when a callback is no
longer needed, and I suspect this is the case for many other
applications.
I mostly develop on SBCL/x86 and ECL, so even if a solution worked on
these platforms only, I'd be really happy.
--J.
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