py/obj: Add support for __int__ special method.

Based on the discussion, this special method is available unconditionally,
as converting to int is a common operation.

1 files changed, 16 insertions, 3 deletions

diff --git a/py/objtype.c b/py/objtype.c
index 0881ae33f..fec73f16e 100644
--- a/py/objtype.c
+++ b/py/objtype.c
@@ -376,6 +376,7 @@ const byte mp_unary_op_method_name[MP_UNARY_OP_NUM_RUNTIME] = {
     [MP_UNARY_OP_BOOL] = MP_QSTR___bool__,
     [MP_UNARY_OP_LEN] = MP_QSTR___len__,
     [MP_UNARY_OP_HASH] = MP_QSTR___hash__,
+    [MP_UNARY_OP_INT] = MP_QSTR___int__,
     #if MICROPY_PY_ALL_SPECIAL_METHODS
     [MP_UNARY_OP_POSITIVE] = MP_QSTR___pos__,
     [MP_UNARY_OP_NEGATIVE] = MP_QSTR___neg__,
@@ -421,9 +422,21 @@ STATIC mp_obj_t instance_unary_op(mp_unary_op_t op, mp_obj_t self_in) {
         return mp_unary_op(op, self->subobj[0]);
     } else if (member[0] != MP_OBJ_NULL) {
         mp_obj_t val = mp_call_function_1(member[0], self_in);
-        // __hash__ must return a small int
-        if (op == MP_UNARY_OP_HASH) {
-            val = MP_OBJ_NEW_SMALL_INT(mp_obj_get_int_truncated(val));
+
+        switch (op) {
+            case MP_UNARY_OP_HASH:
+                // __hash__ must return a small int
+                val = MP_OBJ_NEW_SMALL_INT(mp_obj_get_int_truncated(val));
+                break;
+            case MP_UNARY_OP_INT:
+                // Must return int
+                if (!MP_OBJ_IS_INT(val)) {
+                    mp_raise_TypeError(NULL);
+                }
+                break;
+            default:
+                // No need to do anything
+                ;
         }
         return val;
     } else {