Indentifying OCaml exceptions from C

Indentifying OCaml exceptions from C

[Raj Bandyopadhyay]

Hi ocaml folks

I have a C program that makes callbacks to the OCaml runtime via the 
callback_exn() mechanism. Unfortunately, the OCaml code is raising some 
exception. It seems to be one of the built-in OCaml exceptions, and not 
something that I have defined in my OCaml code.

I would like to know what is the easiest/correct way to identify the 
exact OCaml exception being raised, so I can debug this program.

Thank you
Raj

Re: [Caml-list] Indentifying OCaml exceptions from C

[Alain Frisch]

Raj Bandyopadhyay wrote:
> Hi ocaml folks
> 
> I have a C program that makes callbacks to the OCaml runtime via the 
> callback_exn() mechanism. Unfortunately, the OCaml code is raising some 
> exception. It seems to be one of the built-in OCaml exceptions, and not 
> something that I have defined in my OCaml code.
> 
> I would like to know what is the easiest/correct way to identify the 
> exact OCaml exception being raised, so I can debug this program.

You can use the macros Is_exception_result and Extract_exception 
(defined in callback.h) to check whether the result of callback_exn is 
an exception and to retrieve the exception value in that case. The first 
field of this value points to a block with one field pointing to the 
string representing the exception's constructor name. The other fields 
of the exception value are the exception's arguments.

-- Alain