objtuple: Go out of the way to support comparison of subclasses.

Two things are handled here: allow to compare native subtypes of tuple,
e.g. namedtuple (TODO: should compare type too, currently compared
duck-typedly by content). Secondly, allow user sunclasses of tuples
(and its subtypes) be compared either. "Magic" I did previously in
objtype.c covers only one argument (lhs is many), so we're in trouble
when lhs is native type - there's no other option besides handling
rhs in special manner. Fortunately, this patch outlines approach with
fast path for native types.

1 files changed, 9 insertions, 0 deletions

diff --git a/py/objtype.c b/py/objtype.c
index ef5f6b9d9..c579477db 100644
--- a/py/objtype.c
+++ b/py/objtype.c
@@ -845,6 +845,15 @@ STATIC mp_obj_t mp_builtin_isinstance(mp_obj_t object, mp_obj_t classinfo) {
 
 MP_DEFINE_CONST_FUN_OBJ_2(mp_builtin_isinstance_obj, mp_builtin_isinstance);
 
+mp_obj_t mp_instance_cast_to_native_base(mp_const_obj_t self_in, mp_const_obj_t native_type) {
+    mp_obj_type_t *self_type = mp_obj_get_type(self_in);
+    if (!mp_obj_is_subclass_fast(self_type, native_type)) {
+        return MP_OBJ_NULL;
+    }
+    mp_obj_instance_t *self = (mp_obj_instance_t*)self_in;
+    return self->subobj[0];
+}
+
 /******************************************************************************/
 // staticmethod and classmethod types (probably should go in a different file)