🍖 isinstance( ) 和 issubclass( ) 方法

一. isinstance(obj,cls)

1.isinstance( ) 与 type( )

• 检查一个对象(obj) 是否是类(cls) 实例出来的

class Foo1:
    def __init__(self):
        self.name = "派大星"

class Foo2:
    def __init__(self):
        self.name = "海绵宝宝"

f1 = Foo1()
f2 = Foo2()

print(isinstance(f1,Foo1))  # True
print(isinstance(f2,Foo1))  # False

• type( ) 判断传入对象的类型

print(type([1,2.3]) == list)    # True
print(type(33) is int)          # True
print(type(3.5) in (int,float)) # True

2.不同之处

• isinstance 它可以判断带有继承关系的类的对象
• 而 type 只能判断所属类的对象

class Foo1:
    def __init__(self):
        self.name = "派大星"

class Foo2(Foo1):
        name = "海绵宝宝"

f1 = Foo1()
f2 = Foo2()

print(isinstance(f2,Foo2))  # True
print(isinstance(f2,Foo1))  # True

print(type(f2) is Foo2)     # True
print(type(f2) is Foo1)     # False

3.注意

• 不能说哪一种方法更好, 只能说哪一个更合适

二. issubclass(sub,super)

• 检查sub类是否是super类的派生类(孙子类, 重孙子类...)

🍔多继承
class Foo1:
    def __init__(self):
        self.name = "章鱼哥"

class Bar1:
    def run(self):
        print("快跑")

class Bar2(Bar1,Foo1):
    def run(self):
        print("快跑")

class Bar3:
    def speak(self):
        print("快说")

print(issubclass(Bar2,Foo1))  # True
print(issubclass(Bar2,Bar1))  # True
print(issubclass(Bar3,Bar1))  # False

🍔多层继承 (父类--->父类)
class Foo1:
    def __init__(self):
        self.name = "章鱼哥"

class Bar1(Foo1):
    def run(self):
        print("快跑")

class Bar2(Bar1):
    def run(self):
        print("快跑")

class Bar3(Bar2):
    def speak(self):
        print("快说")

print(issubclass(Bar3,Foo1))  # True
print(issubclass(Bar3,Bar1))  # True
print(issubclass(Bar3,Bar2))  # True