py: Combine load_attr and store_attr type methods into one (attr).

This simplifies the API for objects and reduces code size (by around 400
bytes on Thumb2, and around 2k on x86).  Performance impact was measured
with Pystone score, but change was barely noticeable.

1 files changed, 13 insertions, 4 deletions

diff --git a/py/obj.h b/py/obj.h
index 448db762af..a5423f0824 100644
--- a/py/obj.h
+++ b/py/obj.h
@@ -265,8 +265,7 @@ typedef mp_obj_t (*mp_make_new_fun_t)(mp_obj_t type_in, mp_uint_t n_args, mp_uin
 typedef mp_obj_t (*mp_call_fun_t)(mp_obj_t fun, mp_uint_t n_args, mp_uint_t n_kw, const mp_obj_t *args);
 typedef mp_obj_t (*mp_unary_op_fun_t)(mp_uint_t op, mp_obj_t);
 typedef mp_obj_t (*mp_binary_op_fun_t)(mp_uint_t op, mp_obj_t, mp_obj_t);
-typedef void (*mp_load_attr_fun_t)(mp_obj_t self_in, qstr attr, mp_obj_t *dest); // for fail, do nothing; for attr, dest[0] = value; for method, dest[0] = method, dest[1] = self
-typedef bool (*mp_store_attr_fun_t)(mp_obj_t self_in, qstr attr, mp_obj_t value); // return true if store succeeded; if value==MP_OBJ_NULL then delete
+typedef void (*mp_attr_fun_t)(mp_obj_t self_in, qstr attr, mp_obj_t *dest);
 typedef mp_obj_t (*mp_subscr_fun_t)(mp_obj_t self_in, mp_obj_t index, mp_obj_t value);
 
 typedef struct _mp_method_t {
@@ -330,8 +329,18 @@ struct _mp_obj_type_t {
     mp_unary_op_fun_t unary_op;     // can return MP_OBJ_NULL if op not supported
     mp_binary_op_fun_t binary_op;   // can return MP_OBJ_NULL if op not supported
 
-    mp_load_attr_fun_t load_attr;
-    mp_store_attr_fun_t store_attr; // if value is MP_OBJ_NULL, then delete that attribute
+    // implements load, store and delete attribute
+    //
+    // dest[0] = MP_OBJ_NULL means load
+    //  return: for fail, do nothing
+    //          for attr, dest[0] = value
+    //          for method, dest[0] = method, dest[1] = self
+    //
+    // dest[0,1] = {MP_OBJ_SENTINEL, MP_OBJ_NULL} means delete
+    // dest[0,1] = {MP_OBJ_SENTINEL, object} means store
+    //  return: for fail, do nothing
+    //          for success set dest[0] = MP_OBJ_NULL
+    mp_attr_fun_t attr;
 
     mp_subscr_fun_t subscr;         // implements load, store, delete subscripting
                                     // value=MP_OBJ_NULL means delete, value=MP_OBJ_SENTINEL means load, else store