Re: [Caml-list] C++ Throws

[Brian Hurt <bhurt@spnz.org>]

On Fri, 27 Aug 2004, David McClain wrote:

> I now see that OCaml is not converting anything, per se... Apparently 
> when the throw handler detects an unhandled condition it decides to 
> call abort(), against which there is no defense.

I don't know what precisely is going on here, but Ocaml interfaces to C, 
which doesn't know anything about exceptions.  You might try something 
like (sorry, I'm no C++ guru):

extern "C" value foo(value c);

value foo(value C) {
    /* normal Ocaml wrapper code for C */
    try {
        /* exception throwing code for C++. */
    }
    with (Exception e) {
        /* Translate the C++ exception to an Ocaml exception */
    }
}

The big difference between a C++ function and C function is the name 
mangling.  I doubt Ocaml could find a C++ function for linking after it 
was name mangled.  So the extern "C" tells C++ to not namemangle the 
function name.

There is no way I know of to determine what exceptions a function call 
might throw.

> So there appears to be something relatively complex going on across the 
> foreign function interface with OCaml and C. This override is what 
> frustrates the attempts to create a generic C++ exception handler.

I think you also have a C/C++ interface problem (and yes, Virginia, they 
do exist).

-- 
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                                - Gene Spafford 
Brian

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