This work but code is brittle and dirty

src/pywrenppmodule.cpp

@@ -1,14 +1,22 @@
 #define PY_SSIZE_T_CLEAN
 #include <Python.h>
 #include "wrenpp/vm.hpp"
+#include "wrenpp/vm_fun.hpp"
 #include "wrenpp/def_configuration.hpp"
 #include "config.h"
+#include <vector>
+#include <string_view>
+#include <string>
 
-#define CURR_MODULE_NAME WRENPP_NAME
+#define CURR_MODULE_NAME "py" WRENPP_NAME
 
 namespace {
 struct VMObject;
 int vm_init (VMObject* self, PyObject*, PyObject*);
+PyObject* vm_new (PyTypeObject* type, PyObject*, PyObject*);
+void vm_dealloc (VMObject* self);
+PyObject* vm_interpret (VMObject* self, PyObject* args);
+PyObject* vm_call (VMObject* self, PyObject* args);
 
 class VMConfig : public wren::DefConfiguration {
 public:
@@ -40,31 +48,117 @@ struct VMObject {
 	PyObject_HEAD
 	wren::VM vm;
 };
+//PyMemberDef VMProperties[] = {
+//	{nullptr}
+//};
+PyMethodDef VMMethods[] = {
+	{
+		"interpret",
+		reinterpret_cast<PyCFunction>(vm_interpret),
+		METH_VARARGS,
+		"Interpret a string script"
+	},
+	{
+		"call",
+		reinterpret_cast<PyCFunction>(vm_call),
+		METH_VARARGS,
+		"Call a method from a previously parsed script"
+	},
+	{nullptr}
+};
 
 PyTypeObject VMType = {
 	PyVarObject_HEAD_INIT(NULL, 0)
 	.tp_name = CURR_MODULE_NAME ".VM",
 	.tp_basicsize = sizeof(VMObject),
 	.tp_itemsize = 0,
+	.tp_dealloc = reinterpret_cast<destructor>(vm_dealloc),
 	.tp_flags = Py_TPFLAGS_DEFAULT,
 	.tp_doc = "Wrenpp VM",
+	.tp_methods = VMMethods,
+	.tp_members = nullptr, //VMProperties,
 	.tp_init = reinterpret_cast<initproc>(vm_init),
-	.tp_new = PyType_GenericNew,
+	.tp_new = vm_new,
 };
 
-int vm_init (VMObject* self, PyObject* /*args*/, PyObject* /*kwds*/) {
+PyObject* vm_new (PyTypeObject* type, PyObject* /*args*/, PyObject* /*kwds*/) {
+	VMObject* const self = reinterpret_cast<VMObject*>(type->tp_alloc(type, 0));
+	if (self) {
 		try {
 			VMConfig config;
 			new(&self->vm) wren::VM(&config, nullptr);
 		}
 		catch (...) {
-		return -1;
+			Py_DECREF(self);
+			return nullptr;
 		}
+	}
+	return reinterpret_cast<PyObject*>(self);
+}
+
+void vm_dealloc (VMObject* self) {
+	self->vm.~VM();
+}
+
+int vm_init (VMObject* self, PyObject* /*args*/, PyObject* /*kwds*/) {
+	VMConfig config;
+	self->vm.reset(&config);
 	return 0;
 }
+
+PyObject* vm_interpret (VMObject* self, PyObject* args) {
+	const char* module_name;
+	const char* script;
+	if (!PyArg_ParseTuple(args, "ss", &module_name, &script))
+		return NULL;
+
+	self->vm.interpret(module_name, script);
+	Py_RETURN_NONE;
+}
+
+PyObject* vm_call (VMObject* self, PyObject* args) {
+	const Py_ssize_t argc = PyTuple_Size(args);
+	std::vector<PyObject*> objects;
+	objects.reserve(argc);
+
+	self->vm.ensure_slots(static_cast<std::size_t>(argc) + 1);
+	variable(self->vm, wren::ModuleAndName{"main", "the_user"}, 0);
+
+	std::string func_sig;
+	{
+		Py_ssize_t sz;
+		PyObject* const obj = PyTuple_GetItem(args, 0);
+		const char* const buf = PyUnicode_AsUTF8AndSize(obj, &sz);
+		func_sig.reserve(sz + 3);
+		func_sig.append(buf, sz);
+		func_sig.append(1, '(');
+	}
+
+	for (Py_ssize_t z = 1; z < argc; ++z) {
+		PyObject* const obj = PyTuple_GetItem(args, z);
+		if (not obj)
+			return nullptr;
+
+		const std::string_view type_name(Py_TYPE(obj)->tp_name);
+		//std::cout << "vm_call, parameter " << z+1 << " has type \"" << type_name << "\"\n";
+		if (type_name == "str") {
+			const char* const buf = PyUnicode_AsUTF8(obj);
+			self->vm.set_slot_string(static_cast<std::size_t>(z), buf);
+		}
+		func_sig += "_,";
+	}
+
+	if (func_sig.back() == ',')
+		func_sig.resize(func_sig.size() - 1);
+	func_sig += ")";
+	auto handle = self->vm.make_call_handle(func_sig.c_str());
+	self->vm.call(handle);
+
+	Py_RETURN_NONE;
+}
 } //unnamed namespace
 
-PyMODINIT_FUNC PyInit_wrenpp(void) {
+PyMODINIT_FUNC PyInit_pywrenpp(void) {
 	if (PyType_Ready(&VMType) < 0)
 		return nullptr;
 	PyObject* const m = PyModule_Create(&WrenppModule);