How data hiding works in Python Classes?

Data hiding

In Python, we use double underscore before the attributes name to make them inaccessible/private or to hide them.

The following code shows how the variable __hiddenVar is hidden.

Example

class MyClass:
    __hiddenVar = 0
    def add(self, increment):
       self.__hiddenVar += increment
       print (self.__hiddenVar)
myObject = MyClass()
myObject.add(3)
myObject.add (8)
print (myObject.__hiddenVar)

Output 

3
Traceback (most recent call last):
11
  File "C:/Users/TutorialsPoint1/~_1.py", line 12, in <module>
    print (myObject.__hiddenVar)
AttributeError: MyClass instance has no attribute '__hiddenVar'

In the above program, we tried to access hidden variable outside the class using object and it threw an exception.

We can access the value of hidden attribute by using a special syntax as follows −

Example

class MyClass:
    __hiddenVar = 12
    def add(self, increment):
       self.__hiddenVar += increment
       print (self.__hiddenVar)
myObject = MyClass()
myObject.add(3)
myObject.add (8)
print (myObject._MyClass__hiddenVar)

Output 

15
23
23

Private methods can be accessed from outside their class, but not as easily as in normal cases. Nothing in Python is truly private; internally, the names of private methods and attributes are mangled and unmangled on the fly to make them inaccessible by their given names.