Print a nicer error message when a Python function is not found

dukpy/evaljs.py

@@ -69,6 +69,10 @@ class JSInterpreter(object):
         """
         self._funcs[name] = func
 
+    def _check_exported_function_exists(self, func):
+        func = func.decode('utf-8')
+        return func in self._funcs
+
     def _call_python(self, func, json_args):
         # Arguments came in reverse order from JS
         func = func.decode('utf-8')

src/_support.c

@@ -73,6 +73,15 @@ int call_py_function(duk_context *ctx) {
     duk_pop(ctx);
     duk_pop(ctx);
 
+    ret = PyObject_CallMethod(interpreter, "_check_exported_function_exists",
+                              CONDITIONAL_PY3("y", "s"), pyfuncname);
+
+    if (ret == Py_False) {
+        duk_push_error_object(ctx, DUK_ERR_REFERENCE_ERROR,
+                              "No Python Function named %s", pyfuncname);
+        duk_throw(ctx);
+    }
+
     ret = PyObject_CallMethod(interpreter, "_call_python", CONDITIONAL_PY3("yy", "ss"),
                               pyfuncname, args);