def __new__(cls, *args, **kwargs):
obj = super().__new__(cls, *args, **kwargs)
if cls.__dunders_already_set:
return obj
for attr in OPERATOR_METHODS:
try:
operation = getattr(timedelta, attr)
except AttributeError:
pass
else:
setattr(cls, attr, perform_on_constant(operation))
cls.__dunders_already_set = True
return obj
def test_if_right_operand_is_a_different_type_of_constant_it_uses_it_directly(self):
class T1(Constant):
pass
class T2(Constant):
pass
c1 = T1(1, "one")
c2 = T2(2, "Two")
# even though values are of the same type, since they are different constants
# they cannot be compared.
operation = perform_on_constant(operator.add)
with self.assertRaises(TypeError):
assert operation(c1, c2)
def test_optional_arguments_can_be_provided(self):
c1 = Constant(3, "foo")
operation = perform_on_constant(pow)
assert operation(c1, 3, 4) == 3
def test_if_left_operand_is_not_a_constant_it_uses_it_directly(self):
c1 = Constant(1, "one")
operation = perform_on_constant(operator.add)
assert operation(2, c1) == 3
def test_if_both_operands_are_constants_it_uses_value_of_both(self):
c1 = Constant(1, "one")
c2 = Constant(2, "two")
operation = perform_on_constant(operator.add)
assert operation(c1, c2) == 3