Python子类判断issubclass和实例判断isinstance

# -*- coding: utf-8 -*-
class Animal(object):
    pass
class Cat(Animal):
    pass
class Dog(Animal):
    pass
cat = Cat()

print(issubclass(Cat, Animal))  # True
print(issubclass(Cat, Dog))  # False
# 两种方式等价
print(issubclass(Cat, (Animal, Dog)))  # True
print(issubclass(Cat, Animal) or issubclass(Cat, Dog))  # True

print(isinstance(cat, Animal))  # True
print(isinstance(cat, Cat))  # True
print(isinstance(cat, Dog))  # False
# 两种方式等价
print(isinstance(cat, (Cat, Dog)))  # True
print(isinstance(cat, Cat) or isinstance(cat, Dog))  # True

# -*- coding: utf-8 -*-
class A(object):
    pass
class B(A):
    pass
class C(A):
    pass
for clazz in A.__subclasses__():
    print(clazz.__name__)
# B C