James Bielman wrote:
>Could we be using EQUALP instead for comparing pointers
>(or is the fact that seems to work just a coincidence?)
I realized I didn't specifically answer the question.
No you cannot (or I'd have submitted a patch already :)
You can even write a testcase to prove you cannot. Try EQUALP on
(setq foo (foreign-alloc ...)) and
(unsigned-foreign-address (foreign-address-unsigned foo))
ffi:set-foreign-pointer is the reason.
Try (ffi:foreign-pointer foo) and on others.
That's how in CLISP, you can link all sorts of foreign pointers together, and
invalidate them all in one go. E.g. when calling foreign-free.
See (SETF VALIDP) in the CLISP impnotes.
And yes, INC-POINTER via addition is costly, compared to what could be
otherwise thought of (e.g. Lispworks has an in-place incf-pointer). But that's
not used in CFFI, maybe for fear of destructively modifying the argument? (the
comment in cffi-lispworks invokes another reason).
I could add a similar thing to CLISP, but would it help CFFI?
Regards,
Jorg Hohle.
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