What is the best way to check if an object is a subclass and NOT the base class

Question

let's consider the following code snippet:

class Vehicle:
    pass

class Car(Vehicle):
    pass

my_car = Car()

print(issubclass(type(my_car), Car))
print(issubclass(type(my_car), Vehicle))

Output:

True
True

Now if my task was to tell if my_car is of type Vehicle but not of type Car, how would I do that?

Is there a smart, short, elegant way for this?

Start with [inspect](https://docs.python.org/3/library/inspect.html). — jarmod, Apr 23 '21 at 14:26
If `my_car` is a direct instance of `Vehicle` then `type(my_car) is Vehicle`. If it is an indirect instance of `Vehicle` then `isinstance(my_car, Vehicle) and type(my_car) is not Vehicle`. — khelwood, Apr 23 '21 at 14:28

score 2 · Answer 1 · answered Apr 23 '21 at 14:29

2

If my_car is a direct instance of Vehicle then type(my_car) is Vehicle.

If it is an indirect instance of Vehicle then isinstance(my_car, Vehicle) and type(my_car) is not Vehicle.

answered Apr 23 '21 at 14:29

khelwood

55,782
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score 1 · Answer 2 · answered Apr 23 '21 at 14:28

1

Use isinstance()

isinstance(my_car, Vehicle) and not isinstance(my_car, Car)

answered Apr 23 '21 at 14:28

Barmar

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but in my case both isinstance() would be True, so the full statement would always be False – toto290 Apr 23 '21 at 14:41
That's because `my_car` is a `Car`. You said you want to find out if it's *not* a `Car`. – Barmar Apr 23 '21 at 14:43

score 0 · Answer 3 · answered Apr 23 '21 at 14:39

Please try this code:

class Vehicle:
    pass

class Car(Vehicle):
    pass

my_car = Car()


if type(my_car) == Vehicle and type(my_car) != Car:
    print("my_car is Vehicle")
elif type(my_car) != Vehicle and type(my_car) == Car:
    print("my_car is Car")

What is the best way to check if an object is a subclass and NOT the base class

3 Answers3