Commit 37c6555b authored by Paul Sokolovsky's avatar Paul Sokolovsky
Browse files

obj: Handle user instance hash based on Python adhoc rules.

User instances are hashable by default (using __hash__ inherited from
"object"). But if __eq__ is defined and __hash__ not defined in particular
class, instance is not hashable.
parent 76677270
......@@ -166,20 +166,34 @@ mp_int_t mp_obj_hash(mp_obj_t o_in) {
return mp_obj_tuple_hash(o_in);
} else if (MP_OBJ_IS_TYPE(o_in, &mp_type_type)) {
return (mp_int_t)o_in;
} else if (MP_OBJ_IS_OBJ(o_in)) {
} else if (mp_obj_is_instance_type(mp_obj_get_type(o_in))) {
// if a valid __hash__ method exists, use it
mp_obj_t hash_method[2];
mp_load_method_maybe(o_in, MP_QSTR___hash__, hash_method);
if (hash_method[0] != MP_OBJ_NULL) {
mp_obj_t hash_val = mp_call_method_n_kw(0, 0, hash_method);
mp_obj_t method[2];
mp_load_method_maybe(o_in, MP_QSTR___hash__, method);
if (method[0] != MP_OBJ_NULL) {
mp_obj_t hash_val = mp_call_method_n_kw(0, 0, method);
if (MP_OBJ_IS_INT(hash_val)) {
return mp_obj_int_get_truncated(hash_val);
}
goto error;
}
mp_load_method_maybe(o_in, MP_QSTR___eq__, method);
if (method[0] == MP_OBJ_NULL) {
// https://docs.python.org/3/reference/datamodel.html#object.__hash__
// "User-defined classes have __eq__() and __hash__() methods by default;
// with them, all objects compare unequal (except with themselves) and
// x.__hash__() returns an appropriate value such that x == y implies
// both that x is y and hash(x) == hash(y)."
return (mp_int_t)o_in;
}
// "A class that overrides __eq__() and does not define __hash__() will have its __hash__() implicitly set to None.
// When the __hash__() method of a class is None, instances of the class will raise an appropriate TypeError"
}
// TODO hash class and instances - in CPython by default user created classes' __hash__ resolves to their id
// TODO hash classes
error:
if (MICROPY_ERROR_REPORTING == MICROPY_ERROR_REPORTING_TERSE) {
nlr_raise(mp_obj_new_exception_msg(&mp_type_TypeError, "unhashable type"));
} else {
......
......@@ -19,3 +19,16 @@ class A:
print(hash(A()))
print({A():1})
class B:
pass
hash(B())
class C:
def __eq__(self, another):
return True
try:
hash(C())
except TypeError:
print("TypeError")
Markdown is supported
0% or .
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment