py: Revert mp_load_attr() to its previous state (not supporting default val).

Based on the discussion in #433. mp_load_attr() is critical-path function,
so any extra check will slowdown any script. As supporting default val
required only for getattr() builtin, move correspending implementation
there (still as a separate function due to concerns of maintainability
of such almost-duplicated code instances).

1 files changed, 16 insertions, 0 deletions

diff --git a/py/builtin.c b/py/builtin.c
index 7a01731d0..de1a8fc6a 100644
--- a/py/builtin.c
+++ b/py/builtin.c
@@ -400,6 +400,22 @@ STATIC mp_obj_t mp_builtin_id(mp_obj_t o_in) {
 
 MP_DEFINE_CONST_FUN_OBJ_1(mp_builtin_id_obj, mp_builtin_id);
 
+// See mp_load_attr() if making any changes
+STATIC inline mp_obj_t mp_load_attr_default(mp_obj_t base, qstr attr, mp_obj_t defval) {
+    mp_obj_t dest[2];
+    // use load_method, raising or not raising exception
+    ((defval == MP_OBJ_NULL) ? mp_load_method : mp_load_method_maybe)(base, attr, dest);
+    if (dest[0] == MP_OBJ_NULL) {
+        return defval;
+    } else if (dest[1] == MP_OBJ_NULL) {
+        // load_method returned just a normal attribute
+        return dest[0];
+    } else {
+        // load_method returned a method, so build a bound method object
+        return mp_obj_new_bound_meth(dest[0], dest[1]);
+    }
+}
+
 STATIC mp_obj_t mp_builtin_getattr(uint n_args, const mp_obj_t *args) {
     assert(MP_OBJ_IS_QSTR(args[1]));
     mp_obj_t defval = MP_OBJ_NULL;