]> Hi, Thanks for the help. I have seen another approach mentioned, but have not been able to get it to work. I thought I could rewrite my struct for the IDL as: typedef strcut funp { int i; } funp_t; But leave the C version intact. Supposedly it would just ignore the other field when passing it through to Caml. If that's the case, I was thinking it might be possible to write the following in the IDL: void myfun ([in, unique] funp_t* f) quote(call, " _res = f->funp_fun ();"); So, I guess I would like to be able to ignore a field when converting from C to Caml (and vice versa), but would like to be able to access the field from all code on the C side (even that generated by camlidl). I naively tried adding the function pointer field to the structure in the generated header file, so that my stub code would compile, but that didn't solve my problem. When I call myfun, I got a segmentation fault if I pass it a valid structure. I also tried editing the custom call to check for NULL and failwith a string, but the only change was that after calling with None it would raise an exception -- any valid structure still segfaults. I assume that is because I'm accessing an invalid field in the string, however a simple C program including the same header file can access it without a problem. Any ideas on what is going wrong or how I can fix it? Thanks, Mike On Tue, 23 Jul 2002, Xavier Leroy wrote: > > How would one annotate the following C struct for camlidl: > > > > typedef struct funp { > > int i; > > void (*funp_fun) (); > > } funp_t; > > > > Is it possible? Looking at the specs I don't see how one can have a > > field that is a pointer to a function. Any ideas, or pointers (no pun > > intended) to examples? > > CamlIDL, like the DCE and Microsoft IDL from which it derives, doesn't > support exchanging function pointers between C and Caml. Your best > bet is to declare funp_t as an abstract type in the IDL file: > > typedef [abstract] struct funp * funp_t; > > and export C functions that do what you need to do on this funp_t > type, e.g. > > void invoke(funp_t arg); > > where "invoke" is defined directly in C somewhere else: > > void invoke(funp_t arg) { arg->funp_fun(arg->i); } > > Of course, you won't be able to, say, construct a funp_t where the > function part is actually a Caml function. If you need that kind of > callback mechanism, you'll have to write some of the stub code by hand, > using Caml's callback functions. Alternatively, if you can re-shape > your struct funp till it looks like a COM interface, you could then use > the CamlIDL "interface" declaration and get Caml->C and C->Caml calls. > > Hope this helps, > > - Xavier Leroy > ------------------- > To unsubscribe, mail caml-list-request@inria.fr Archives: http://caml.inria.fr > Bug reports: http://caml.inria.fr/bin/caml-bugs FAQ: http://caml.inria.fr/FAQ/ > Beginner's list: http://groups.yahoo.com/group/ocaml_beginners > ------------------- To unsubscribe, mail caml-list-request@inria.fr Archives: http://caml.inria.fr Bug reports: http://caml.inria.fr/bin/caml-bugs FAQ: http://caml.inria.fr/FAQ/ Beginner's list: http://groups.yahoo.com/group/ocaml_beginners