py/objtype: Add __dict__ attribute for class objects.

pi-anl · pi-anl · commit cb146550aad6 · 2020-06-09T16:30:34.000+10:00
diff --git a/py/objtype.c b/py/objtype.c
@@ -587,17 +587,20 @@ STATIC void mp_obj_instance_load_attr(mp_obj_t self_in, qstr attr, mp_obj_t *des
     }
     #if MICROPY_CPYTHON_COMPAT
     if (attr == MP_QSTR___dict__) {
-        // Create a new dict with a copy of the instance's map items.
+        // Returns a read-only dict of the instance members.
+        // If the internal locals is not fixed, a copy will be created.
         // This creates, unlike CPython, a 'read-only' __dict__: modifying
         // it will not result in modifications to the actual instance members.
-        mp_map_t *map = &self->members;
-        mp_obj_t attr_dict = mp_obj_new_dict(map->used);
-        for (size_t i = 0; i < map->alloc; ++i) {
-            if (mp_map_slot_is_filled(map, i)) {
-                mp_obj_dict_store(attr_dict, map->table[i].key, map->table[i].value);
-            }
+        mp_obj_t members_dict = mp_obj_new_dict(0);
+        mp_obj_dict_t *dict = MP_OBJ_TO_PTR(members_dict);
+        dict->map = self->members;
+        if (dict->map.is_fixed) {
+            dest[0] = dict;
+        } else {
+            dest[0] = mp_obj_dict_copy(MP_OBJ_FROM_PTR(dict));
+            dict = MP_OBJ_TO_PTR(dest[0]);
+            dict->map.is_fixed = 1;
         }
-        dest[0] = attr_dict;
         return;
     }
     #endif
@@ -1015,7 +1018,16 @@ STATIC void type_attr(mp_obj_t self_in, qstr attr, mp_obj_t *dest) {
         }
         #if MICROPY_CPYTHON_COMPAT
         if (attr == MP_QSTR___dict__) {
-            dest[0] = mp_obj_dict_copy(MP_OBJ_FROM_PTR(self->locals_dict));
+            // Returns a read-only dict of the class attributes.
+            // If the internal locals is not fixed, a copy will be created.
+            mp_obj_dict_t *dict = MP_OBJ_FROM_PTR(self->locals_dict);
+            if (dict->map.is_fixed) {
+                dest[0] = dict;
+            } else {
+                dest[0] = mp_obj_dict_copy(dict);
+                dict = MP_OBJ_TO_PTR(dest[0]);
+                dict->map.is_fixed = 1;
+            }
             return;
         }
         #endif
diff --git a/tests/basics/class_dict.py b/tests/basics/class_dict.py
@@ -0,0 +1,10 @@
+
+class Foo:
+    self.a = 1
+    self.b = "bar"
+
+if not hasattr(Foo, "__dict__"):
+    print("SKIP")
+    raise SystemExit
+
+print(Foo.__dict__ == {'a': 1, 'b': 'bar'})
