avoiding crashes when trying to call a c++ callback from octave

[GuidoRamon]

Hello everyone,

I have an issue with dispatching classes in GNU Octave 8.4 on Windows 10. I installed it via the x64 exe installer.

I am trying to call a c++ function in GNU octave, so I use a dispatcher *.cc file as follows, which I then successfully compile into an oct-file:

mkoctfile my_dispatcher_function.cc -c
mkoctfile my_dispatcher_function.o my_cpp_class_pimpl.o -lquadmath

#include<octave/oct.h>
#include<octave/dNDArray.h>

/* body and inline-members of My_cpp_class */

DEFUN_DLD(my_dispatcher_function, args, nargout, "Debugging_my_dispatcher_function_suitable_name"){

    //

    // flag = My_cpp_class.my_cpp_function();

    //

    // ++++ possess an instance

    static My_cpp_class my_class_instance; // I also tried without "static", i.e. re-instantiating at each call. Same behaviour (i.e. octave closes).

    //

    // ++++ acquire arrays

    NDArray array_x = args(0).array_value();
    NDArray array_y = args(1).array_value();

    //

    // ++++ load inputs into class

    for(int i=0;i<10;++i){ my_class_instance.x[i] = array_x(i); }

    //

    // ++++ compute

    my_class_instance.compute();

    //

    // ++++ export outputs

    for(int i=0;i<20;++i){ array_y(i) = my_class_instance.y[i]; }

    //

    // ++++ pack and return result

    octave_value_list retval;

    //

    retval.append( octave_value(array_y ) );

    return retval;

}

The Octave code, which calls the oct file, is:

assert( size(x)==[10,1] && size(x)==[20,1] ); % this passes successfully

y = my_dispatcher_function(x,y);

The constructor of My_cpp_class relies on a singleton, which has been implemented with a non-member function that returns a static instance of the Singleton.

Everytime I call the dispatcher from Octave GUI, Octave immediately closes all windows of the software and ends. (Maybe a subgroup of us can agree that either my class leaks or Octave encounters a bug. I have debugged my class. I would appreciate avoiding a discussion into that area.)

I do not know or want to know or discuss whether this is a bug.

I am interested in acquiring a means to doing what the above code would be expected to do under reasonable naive assumptions (which are: I have a class. I can construct and destruct instances of it in c++ multiple times without memory leaks. Each instance has buffers x,y and a member function compute that manipulates y. I want to obtain y in Octave from given x in Octave).

Currently, my work-around is to write a text file in octave, then make a system call from octave to my cpp exe, this manipulates the textfile, and octave reads the results. The issue is with speed of execution, since the write to harddrive introduces enourmous latency, particularly since I need ~10000 evalations per use case.

Thank you for any help.

Kind regards,

Guido