add some `final` kw

src/iter.h

@@ -4,7 +4,7 @@
 
 namespace pkpy{
 
-class RangeIter : public BaseIter {
+class RangeIter final: public BaseIter {
     i64 current;
     Range r;    // copy by value, so we don't need to keep ref
 public:
@@ -25,7 +25,7 @@ public:
 };
 
 template <typename T>
-class ArrayIter : public BaseIter {
+class ArrayIter final: public BaseIter {
     PyObject* ref;
     int index;
 public:
@@ -42,7 +42,7 @@ public:
     }
 };
 
-class StringIter : public BaseIter {
+class StringIter final: public BaseIter {
     PyObject* ref;
     int index;
 public:

src/obj.h

@@ -88,7 +88,7 @@ struct GCHeader {
     GCHeader() : enabled(true), marked(false) {}
 };
 
-struct PyObject {
+struct PyObject{
     GCHeader gc;
     Type type;
     NameDict* _attr;
@@ -111,7 +111,7 @@ template<typename T>
 void gc_mark(T& t);
 
 template <typename T>
-struct Py_ : PyObject {
+struct Py_ final: PyObject {
     T _value;
 
     Py_(Type type, const T& val): PyObject(type), _value(val) { _init(); }

src/vm.h

@@ -32,7 +32,7 @@ Str _read_file_cwd(const Str& name, bool* ok);
     inline PyObject* py_var(VM* vm, ctype&& value) { return vm->heap.gcnew(vm->ptype, std::move(value));}
 
 
-class Generator: public BaseIter {
+class Generator final: public BaseIter {
     Frame frame;
     int state; // 0,1,2
 public: