py/objtype: Refactor object's handling of __new__ to not create 2 objs.

Before this patch, if a user defined the __new__() function for a class
then two instances of that class would be created: once before __new__ is
called and once during the __new__ call (assuming the user creates some
instance, eg using super().__new__, which is most of the time).  The first
one was then discarded.  This refactor makes it so that a new instance is
only created if the user __new__ function doesn't exist.

1 files changed, 6 insertions, 3 deletions

diff --git a/py/objobject.c b/py/objobject.c
index 49d2ec62e..265fcfbf2 100644
--- a/py/objobject.c
+++ b/py/objobject.c
@@ -52,9 +52,12 @@ STATIC mp_obj_t object___new__(mp_obj_t cls) {
     if (!MP_OBJ_IS_TYPE(cls, &mp_type_type) || !mp_obj_is_instance_type((mp_obj_type_t*)MP_OBJ_TO_PTR(cls))) {
         mp_raise_TypeError("__new__ arg must be a user-type");
     }
-    mp_obj_t o = MP_OBJ_SENTINEL;
-    mp_obj_t res = mp_obj_instance_make_new(MP_OBJ_TO_PTR(cls), 1, 0, &o);
-    return res;
+    // This executes only "__new__" part of instance creation.
+    // TODO: This won't work well for classes with native bases.
+    // TODO: This is a hack, should be resolved along the lines of
+    // https://github.com/micropython/micropython/issues/606#issuecomment-43685883
+    const mp_obj_type_t *native_base;
+    return MP_OBJ_FROM_PTR(mp_obj_new_instance(MP_OBJ_TO_PTR(cls), &native_base));
 }
 STATIC MP_DEFINE_CONST_FUN_OBJ_1(object___new___fun_obj, object___new__);
 STATIC MP_DEFINE_CONST_STATICMETHOD_OBJ(object___new___obj, MP_ROM_PTR(&object___new___fun_obj));