Customize attribute access for object

py/mpconfig.h

@@ -635,6 +635,17 @@ typedef double mp_float_t;
 #define MICROPY_PY_DESCRIPTORS (0)
 #endif
 
+// Whether to support (__delattr__ and __setattr__)
+// This costs some code size and makes all load attrs and store attrs slow
+#ifndef MICROPY_PY_METHODS_DELATTRS_SETATTRS
+#define MICROPY_PY_METHODS_DELATTRS_SETATTRS (0)
+#endif
+
+// Whether to support object (__delattr__, __getattribute__ and __setattr__)
+#ifndef MICROPY_PY_OBJECT_METHODS_DELATTRS_SETATTRS
+#define MICROPY_PY_OBJECT_METHODS_DELATTRS_SETATTRS (0)
+#endif
+
 // Support for async/await/async for/async with
 #ifndef MICROPY_PY_ASYNC_AWAIT
 #define MICROPY_PY_ASYNC_AWAIT (1)

py/objobject.c

@@ -59,13 +59,53 @@ STATIC mp_obj_t object___new__(mp_obj_t cls) {
 STATIC MP_DEFINE_CONST_FUN_OBJ_1(object___new___fun_obj, object___new__);
 STATIC MP_DEFINE_CONST_STATICMETHOD_OBJ(object___new___obj, MP_ROM_PTR(&object___new___fun_obj));
 
+#if MICROPY_PY_OBJECT_METHODS_DELATTRS_SETATTRS
+STATIC mp_obj_t object___setattr__(mp_obj_t self_in, mp_obj_t attr_in, mp_obj_t value) {
+    mp_obj_instance_t *self = MP_OBJ_TO_PTR(self_in);
+    mp_map_lookup(&self->members, MP_OBJ_NEW_QSTR(mp_obj_str_get_qstr(attr_in)), MP_MAP_LOOKUP_ADD_IF_NOT_FOUND)->value = value;
+    return value;
+}
+MP_DEFINE_CONST_FUN_OBJ_3(object___setattr___obj, object___setattr__);
+
+STATIC mp_obj_t object___getattribute__(mp_obj_t self_in, mp_obj_t attr_in) {
+    mp_obj_instance_t *self = MP_OBJ_TO_PTR(self_in);
+    qstr attr = mp_obj_str_get_qstr(attr_in);
+    // check if exists into locals_dict and return its value
+    // if this fails to load the requested attr, we raise attribute error
+    mp_map_elem_t *elem = mp_map_lookup(&self->members, MP_OBJ_NEW_QSTR(attr), MP_MAP_LOOKUP);
+    if (elem == NULL) {
+        nlr_raise(mp_obj_new_exception_msg_varg(&mp_type_AttributeError,
+            "'%s' object has no attribute '%q'",
+            mp_obj_get_type_str(self_in), attr));
+    }
+    return elem->value;
+}
+MP_DEFINE_CONST_FUN_OBJ_2(object___getattribute___obj, object___getattribute__);
+
+STATIC mp_obj_t object___delattr__(mp_obj_t self_in, mp_obj_t attr_in) {
+    mp_obj_instance_t *self = MP_OBJ_TO_PTR(self_in);
+    mp_map_lookup(&self->members, MP_OBJ_NEW_QSTR(mp_obj_str_get_qstr(attr_in)), MP_MAP_LOOKUP_REMOVE_IF_FOUND);
+    return mp_const_none;
+}
+MP_DEFINE_CONST_FUN_OBJ_2(object___delattr___obj, object___delattr__);
+#endif
+
 STATIC const mp_rom_map_elem_t object_locals_dict_table[] = {
     #if MICROPY_CPYTHON_COMPAT
     { MP_ROM_QSTR(MP_QSTR___init__), MP_ROM_PTR(&object___init___obj) },
     #endif
     #if MICROPY_CPYTHON_COMPAT
     { MP_ROM_QSTR(MP_QSTR___new__), MP_ROM_PTR(&object___new___obj) },
     #endif
+    #if (MICROPY_CPYTHON_COMPAT && MICROPY_PY_OBJECT_METHODS_DELATTRS_SETATTRS)
+    { MP_ROM_QSTR(MP_QSTR___delattr__), MP_ROM_PTR(&object___delattr___obj) },
+    #endif
+    #if (MICROPY_CPYTHON_COMPAT && MICROPY_PY_OBJECT_METHODS_DELATTRS_SETATTRS)
+    { MP_ROM_QSTR(MP_QSTR___getattribute__), MP_ROM_PTR(&object___getattribute___obj) },
+    #endif
+    #if (MICROPY_CPYTHON_COMPAT && MICROPY_PY_OBJECT_METHODS_DELATTRS_SETATTRS)
+    { MP_ROM_QSTR(MP_QSTR___setattr__), MP_ROM_PTR(&object___setattr___obj) },
+    #endif
 };
 
 STATIC MP_DEFINE_CONST_DICT(object_locals_dict, object_locals_dict_table);

py/objtype.c

@@ -533,6 +533,14 @@ STATIC void mp_obj_instance_load_attr(mp_obj_t self_in, qstr attr, mp_obj_t *des
 
     // try __getattr__
     if (attr != MP_QSTR___getattr__) {
+        #if MICROPY_PY_METHODS_DELATTRS_SETATTRS
+        // if the requested attr is __setattr__ assign MP_OBJECT_NULL to dest[0] to indicate success
+        if (attr == MP_QSTR___setattr__) {
+            dest[0] = MP_OBJ_NULL;
+            return;
+        }
+        #endif
+
         mp_obj_t dest2[3];
         mp_load_method_maybe(self_in, MP_QSTR___getattr__, dest2);
         if (dest2[0] != MP_OBJ_NULL) {
@@ -626,10 +634,39 @@ STATIC bool mp_obj_instance_store_attr(mp_obj_t self_in, qstr attr, mp_obj_t val
 
     if (value == MP_OBJ_NULL) {
         // delete attribute
+        #if MICROPY_PY_METHODS_DELATTRS_SETATTRS
+        // try __delattr__ first
+        if (attr != MP_QSTR___delattr__) {
+            mp_obj_t attr_delattr_method[3];
+            mp_load_method_maybe(self_in, MP_QSTR___delattr__, attr_delattr_method);
+            if (attr_delattr_method[0] != MP_OBJ_NULL) {
+                // __delattr__ exists, call it and return its result
+                attr_delattr_method[2] = MP_OBJ_NEW_QSTR(attr);
+                mp_call_method_n_kw(1, 0, attr_delattr_method);
+                return true;
+            }
+        }
+        #endif
+
         mp_map_elem_t *elem = mp_map_lookup(&self->members, MP_OBJ_NEW_QSTR(attr), MP_MAP_LOOKUP_REMOVE_IF_FOUND);
         return elem != NULL;
     } else {
         // store attribute
+        #if MICROPY_PY_METHODS_DELATTRS_SETATTRS
+        // try __setattr__ first
+        if (attr != MP_QSTR___setattr__) {
+            mp_obj_t attr_setattr_method[4];
+            mp_load_method_maybe(self_in, MP_QSTR___setattr__, attr_setattr_method);
+            if (attr_setattr_method[0] != MP_OBJ_NULL) {
+                // __setattr__ exists, call it and return its result
+                attr_setattr_method[2] = MP_OBJ_NEW_QSTR(attr);
+                attr_setattr_method[3] = value;
+                mp_call_method_n_kw(2, 0, attr_setattr_method);
+                return true;
+            }
+        }
+        #endif
+
         mp_map_lookup(&self->members, MP_OBJ_NEW_QSTR(attr), MP_MAP_LOOKUP_ADD_IF_NOT_FOUND)->value = value;
         return true;
     }

py/runtime.c

@@ -932,7 +932,11 @@ STATIC mp_obj_t checked_fun_call(mp_obj_t self_in, size_t n_args, size_t n_kw, c
     mp_obj_checked_fun_t *self = MP_OBJ_TO_PTR(self_in);
     if (n_args > 0) {
         const mp_obj_type_t *arg0_type = mp_obj_get_type(args[0]);
-        if (arg0_type != self->type) {
+        if (arg0_type != self->type
+            #if MICROPY_PY_OBJECT_METHODS_DELATTRS_SETATTRS
+            && !MP_OBJ_IS_TYPE(arg0_type, &mp_type_type)
+            #endif
+            ) {
             if (MICROPY_ERROR_REPORTING != MICROPY_ERROR_REPORTING_DETAILED) {
                 mp_raise_msg(&mp_type_TypeError, "argument has wrong type");
             } else {

tests/basics/delsetattr.py

@@ -0,0 +1,27 @@
+# test __delattr__ and __setattr__
+
+class A:
+    def __init__(self, d):
+        A.d = d
+
+    def __getattr__(self, attr):
+        if attr in A.d:
+            return A.d[attr]
+        else:
+            raise AttributeError(attr)
+
+    def __setattr__(self, attr, value):
+        A.d[attr] = value
+
+    def __delattr__(self, attr):
+        del A.d[attr]
+
+a = A({"a":1, "b":2})
+print(a.a, a.b)
+a.a = 3
+try:
+    print(a.a, a.b)
+    del a.a
+    print(a.a)
+except AttributeError:
+    print("AttributeError")

tests/basics/object_delgetsetattr.py

@@ -0,0 +1,34 @@
+
+class A:
+
+    def __init__(self, a=0, b=0, c=0, d=b''):
+        self._a = a
+        self._b = b
+        self._c = c
+        self._d = d
+
+    def __getattr__(self, name):
+        if not name.startswith("_"):
+            name = "_" + name
+        return object.__getattribute__(self, name)
+
+    def __setattr__(self, name, value):
+        if not name.startswith("_"):
+            name = "_" + name
+        object.__setattr__(self, name, value)
+
+    def __delattr__(self, name):
+        if not name.startswith("_"):
+            name = "_" + name
+        object.__delattr__(self, name)
+
+
+a = A(1, 2, 3, b'value')
+a.e = 4
+print(a.e)
+print(a.b)
+try:
+    del a.c
+    print(a.c)
+except AttributeError as ae:
+    print("AttributeError", ae)

tests/run-tests

@@ -228,6 +228,8 @@ def run_tests(pyb, tests, args):
 
     if not has_coverage:
         skip_tests.add('cmdline/cmd_parsetree.py')
+        skip_tests.add('basics/delsetattr.py')
+        skip_tests.add('basics/object_delgetsetattr.py')
 
     # Some tests shouldn't be run on a PC
     if pyb is None:

unix/mpconfigport_coverage.h

@@ -36,3 +36,5 @@
 #define MICROPY_FSUSERMOUNT            (1)
 #define MICROPY_VFS_FAT                (1)
 #define MICROPY_PY_FRAMEBUF            (1)
+#define MICROPY_PY_METHODS_DELATTRS_SETATTRS (1)
+#define MICROPY_PY_OBJECT_METHODS_DELATTRS_SETATTRS (1)