The example demonstrates private properties in Python

In Python, you can define a property to be private by placing a double underscore before the name of the property variable. For example:

#! encoding=UTF-8

 

class A:

    def __init__(self):

         

        #  Define private properties 

        self.__name = "wangwu"

         

        #  Common attribute definition 

        self.age = 19

         

a = A()

 

#  Normal output 

print a.age

 

#  The property cannot be found 

print a.__name

Execution output:

Traceback (most recent call last):

  File "C:UsersleeDocumentsAptana Studio 3 Workspacetestaa.py", line 19, in <module>

    print a.__name

AttributeError: A instance has no attribute '__name'

Accessing private property with s/s, you can't find the property member, not the permission, etc.

#! encoding=UTF-8

 

class A:

    def __init__(self):

         

        #  Define private properties 

        self.__name = "wangwu"

         

        #  Common attribute definition 

        self.age = 19

         

 

a = A()

 

a.__name = "lisi"

print a.__name

Execution results:
1
lisi
In Python, even inheritance cannot access private variables to each other, such as:

#! encoding=UTF-8

 

class A:

    def __init__(self):

         

        #  Define private properties 

        self.__name = "wangwu"

         

        #  Common attribute definition 

        self.age = 19

         

 

class B(A):

    def sayName(self):

        print self.__name

         

 

b = B()

b.sayName()

Execution results:

Traceback (most recent call last):

  File "C:UsersleeDocumentsAptana Studio 3 Workspacetestaa.py", line 19, in <module>

    b.sayName()

  File "C:UsersleeDocumentsAptana Studio 3 Workspacetestaa.py", line 15, in sayName

    print self.__name

AttributeError: B instance has no attribute '_B__name'

Or a parent class can't access private properties of a subclass, such as:

#! encoding=UTF-8

 

class A:

    def say(self):

        print self.name

        print self.__age

         

 

class B(A):

    def __init__(self):

        self.name = "wangwu"

        self.__age = 20

 

b = B()

b.say()

Execution results:

wangwu

Traceback (most recent call last):

  File "C:UsersleeDocumentsAptana Studio 3 Workspacetestaa.py", line 15, in <module>

    b.say()

  File "C:UsersleeDocumentsAptana Studio 3 Workspacetestaa.py", line 6, in say

    print self.__age

AttributeError: B instance has no attribute '_A__age'