从基类扩展方法时发生TypeError

Question

我试图测试一个简单的Python继承案例，但是我在理解Python解释器抛出的错误时遇到了问题

class Mainclass(object):
    """
     Class to test the inheritance
    """
    def __init__(self,somevalue):
        self.somevalue = somevalue
    def display(self):
        print(self.somevalue)


class Inherited(Mainclass):
    """
    Inherited class from the Main Class
    """
    def display(self):
        print("**********")
        Mainclass.display()
        print("**********")

c = Inherited(100)
c.display()

我只是想给Inherited类中显示的输出添加星号，那么为什么会出现以下错误呢

Traceback (most recent call last):
line 21, in <module>
c.display()
line 17, in display
Mainclass.display()
TypeError: display() missing 1 required positional argument: 'self'

Answer 1

正确的方法是这样调用super

# Python 2.7 using new style classes
class Inherited(Mainclass):
"""
Inherited class from the Main Class
"""
    def display(self):
        print("**********")
        super(Mainclass,self).display(self)
        print("**********")

或者这样

# Python 3.x
class Inherited(Mainclass):
"""
Inherited class from the Main Class
"""
    def display(self):
        print("**********")
        super().display(self)
        print("**********")