Function c_call_function_impl

tutorials/integration/c/04_callbacks.c:42–66

----------------------------------------------------------------------- Interop: c_call_function — receives a function pointer and calls it daslang signature: def c_call_function(callback : function<(a:int; b:float) : string>; a : int; b : float) : string Mangled: "s 0 @@ i f" return "s" (string) arg 0: "0 @@" — function pointer taking (int, float) returning string arg 1: "i" (int) arg 2

//   arg 2: "f" (float)
// -----------------------------------------------------------------------
vec4f c_call_function_impl(das_context * ctx, das_node * node, vec4f * args) {
    (void)node;
    das_function * callback = das_argument_function(args[0]);
    int    a = das_argument_int(args[1]);
    float  b = das_argument_float(args[2]);

    printf("[C] calling function pointer with (%d, %.2f)\n", a, b);

    // Build arguments for the callback.
    vec4f cb_args[2];
    cb_args[0] = das_result_int(a);
    cb_args[1] = das_result_float(b);

    // Call the daslang function.
    vec4f ret = das_context_eval_with_catch(ctx, callback, cb_args);
    char * ex = das_context_get_exception(ctx);
    if (ex) {
        printf("[C] exception in callback: %s\n", ex);
        return das_result_string(NULL);
    }

    char * str = das_argument_string(ret);
    printf("[C] callback returned: \"%s\"\n", str);
    return ret;
}

// -----------------------------------------------------------------------
// Interop: c_call_lambda — receives a lambda and calls it