I have experimented with adding C++ exception handling to the wrap. It
seems, using gcc, that it works fine, as long as one does not try to
pass a C++ exception through a C function call - then it calls the
terminate handler.
So add an exception type to Guile which can hold the thrown data, a
pair (key . args) with a predicate
SCM_API int scm_is_exception(SCM x);
When there is an uncaught exception in a C function returning SCM, it
should instead return this exception type with the thrown data. (So
there would need to be some variable present, changing the behavior of
these C-functions.)
Then write a function (object = C++ version of SCM)
object rethrow(const object& x) {
if (scm_is_exception(x))
throw (exception)x;
else
return x;
}
Then just add this rethrow() to the returns that might be an exception:
number operator/(const number& x, const number& y) { return
rethrow(scm_divide(x, y)); }
instead of
number operator/(const number& x, const number& y) { return
scm_divide(x, y); }
The code should then look normal:
try {
integer x = 1, y = 0;
integer z = x/y; // exception
catch (exception& x) {
out << "Exception: " << x << newline;
}
I did some code using scm_internal_catch(), but it takes a body
function of only one argument:
SCM body(void *data);
So I guess one has to fiddle around with passing suitable structs
using it. - May try it later.
Hans
