py: Introduce MP_ROM_NONE macro for ROM to refer to None object.

This helps to prevent mistakes, and allows easily changing the ROM value of
None if needed.

3 files changed, 9 insertions, 5 deletions

diff --git a/py/obj.h b/py/obj.h
index 7c6815a3c..189f37d07 100644
--- a/py/obj.h
+++ b/py/obj.h
@@ -242,6 +242,10 @@ typedef union _mp_rom_obj_t { uint64_t u64; struct { const void *lo, *hi; } u32;
 
 // Macros to create objects that are stored in ROM.
 
+#ifndef MP_ROM_NONE
+#define MP_ROM_NONE MP_ROM_PTR(&mp_const_none_obj)
+#endif
+
 #ifndef MP_ROM_INT
 typedef mp_const_obj_t mp_rom_obj_t;
 #define MP_ROM_INT(i) MP_OBJ_NEW_SMALL_INT(i)
diff --git a/py/objlist.c b/py/objlist.c
index 29a1d8b1a..00afcd56a 100644
--- a/py/objlist.c
+++ b/py/objlist.c
@@ -312,7 +312,7 @@ STATIC void mp_quicksort(mp_obj_t *head, mp_obj_t *tail, mp_obj_t key_fn, mp_obj
 // TODO Python defines sort to be stable but ours is not
 mp_obj_t mp_obj_list_sort(size_t n_args, const mp_obj_t *pos_args, mp_map_t *kw_args) {
     static const mp_arg_t allowed_args[] = {
-        { MP_QSTR_key, MP_ARG_KW_ONLY | MP_ARG_OBJ, {.u_rom_obj = MP_ROM_PTR(&mp_const_none_obj)} },
+        { MP_QSTR_key, MP_ARG_KW_ONLY | MP_ARG_OBJ, {.u_rom_obj = MP_ROM_NONE} },
         { MP_QSTR_reverse, MP_ARG_KW_ONLY | MP_ARG_BOOL, {.u_bool = false} },
     };
 
diff --git a/py/objproperty.c b/py/objproperty.c
index 49cb9ca1b..2a7844b60 100644
--- a/py/objproperty.c
+++ b/py/objproperty.c
@@ -39,10 +39,10 @@ typedef struct _mp_obj_property_t {
 STATIC mp_obj_t property_make_new(const mp_obj_type_t *type, size_t n_args, size_t n_kw, const mp_obj_t *args) {
     enum { ARG_fget, ARG_fset, ARG_fdel, ARG_doc };
     static const mp_arg_t allowed_args[] = {
-        { MP_QSTR_, MP_ARG_OBJ, {.u_rom_obj = MP_ROM_PTR(&mp_const_none_obj)} },
-        { MP_QSTR_, MP_ARG_OBJ, {.u_rom_obj = MP_ROM_PTR(&mp_const_none_obj)} },
-        { MP_QSTR_, MP_ARG_OBJ, {.u_rom_obj = MP_ROM_PTR(&mp_const_none_obj)} },
-        { MP_QSTR_doc, MP_ARG_OBJ, {.u_rom_obj = MP_ROM_PTR(&mp_const_none_obj)} },
+        { MP_QSTR_, MP_ARG_OBJ, {.u_rom_obj = MP_ROM_NONE} },
+        { MP_QSTR_, MP_ARG_OBJ, {.u_rom_obj = MP_ROM_NONE} },
+        { MP_QSTR_, MP_ARG_OBJ, {.u_rom_obj = MP_ROM_NONE} },
+        { MP_QSTR_doc, MP_ARG_OBJ, {.u_rom_obj = MP_ROM_NONE} },
     };
     mp_arg_val_t vals[MP_ARRAY_SIZE(allowed_args)];
     mp_arg_parse_all_kw_array(n_args, n_kw, args, MP_ARRAY_SIZE(allowed_args), allowed_args, vals);