[Ecls-list] exception question

[worm]

> Is it possible to throw a C++ exception within a
> application callback function (i.e. a function set up
> via a call to cl_def_c_function() or
> cl_make_cclosure_va()) and have that exception
> propagate through the embedded interpreter, back to
> the calling application?
>
> I'm trying to do this using 'throw runtime_error(...'
> but I get "System error. Trying to recover ..." from
> the interpreter when the exception is thrown.

This error is not from ECL :-/ Did you compile ECL using a C++ compiler
(option --with-cxx at configuration time)? If so, then I really do not
know how ECL can interfere with the exception system from C++. The only
fancy thing ECL uses are setjmp/longjmp, but they are standard and
should be tolerated by C++.

However, throwing exceptions may leave the ECL interpreter in an
undesirable state of confusion. If you use the lisp mechanisms (either
with frs_push or with the macros to implement UNWIND-PROTECT), then you
can also get exceptions, but the lisp environment remains at all times
consistent (variable bindings are undone, stacks are properly restored,
etc).

Maybe if ECL had been implemented in C++, things would have been
different, but right now the setjmp/longjmp mechanism does what we want.

Regards,

Juanjo