Konrad, I would create a wrapper like this:
(define-fooapi make-foo (_fun (foo : (_ptr o _foo) -> (r : _int) -> (if r (begin (register-finalizer-and-custodian-shutdown foo destroy-foo) foo) (error "can not make foo"))) Regards, Dmitry On 01/24/2018 10:47 PM, Konrad Hinsen wrote:
Hi everyone, I am working on an FFI which overall progresses well - the Racket FFI library is really a very nice tool to have. The one problem I couldn't solve yet is handling resource allocation. My use case is very similar to what allocator/deallocator are meant for, except that the allocated object is not the return value of any function, and therefore I cannot use allocator. I have an API like int make_foo(foo** new_foo); int destroy_foo(foo* a_foo); so my FFI definitions look like (define _foo (_cpointer 'foo)) (define-fooapi make-foo (_fun (foo : (_ptr o _foo) -> (r : _int) -> (values r foo)) (define-fooapi destroy-foo (_fun _foo -> _void)) Given that make-foo returns two values, I cannot use #:wrap to make it an allocator. Since the C API I am wrapping is pretty standard, I suspect others have had this problem before. Any suggestions? Thanks in advance, Konrad.
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