python中的_和__用法及说明

class A:
    def _method(self):
        print('约定为不在类的外面直接调用这个方法，但是也可以调用')
    def method(self):
        return self._method()     
a = A()

In [24]: a.method()

In [25]: a._method()

class A:

    def __method(self):
        print('This is a method from class A')

    def method(self):
        return self.__method()

class B(A):
    def __method(self):
        print('This is a method from calss B')

In [27]: a = A()

In [28]: b = B()

In [29]: a.method()
This is a method from class A

In [30]: b.method()
This is a method from class A

In [35]: a.__method()
---------------------------------------------------------------------------
AttributeError                            Traceback (most recent call last)
<ipython-input-35-b8e0b1bf4d09> in <module>()
----> 1 a.__method()

AttributeError: 'A' object has no attribute '__method'

In [36]: a._A__method()
This is a method from class A

class B(A):
    def __method(self):
        print('This is a method from calss B')

    def method(self):
        return self.__method()

In [32]: b = B()

In [33]: b.method()
This is a method from calss B