Thanks for the suggestion, let me take a good look at callbacks. Another thing that I can't make work elegantly is compiling template functions from C++, since

Thanks for the suggestion, let me take a good look at callbacks. Another thing that I can't make work elegantly is compiling template functions from C++, since we have no clue to guess which types will be instantiated in the Python code (and they can even depend on user input, so only determined at runtime)