Protected variable in Python
Last Updated :
10 Jan, 2020
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Prerequisites: Underscore ( _ ) in Python
A Variable is an identifier that we assign to a memory location which is used to hold values in a computer program. Variables are named locations of storage in the program. Based on access specification, variables can be public, protected and private in a class.
Protected variables are those data members of a class that can be accessed within the class and the classes derived from that class. In Python, there is no existence of “Public” instance variables. However, we use underscore '_' symbol to determine the access control of a data member in a class. Any member prefixed with an underscore should be treated as a non-public part of the API or any Python code, whether it is a function, a method or a data member.
Example 1:
Python3
Output:
Python3
Output:
# program to illustrate protected
# data members in a class
# Defining a class
class Geek:
# protected data members
_name = "R2J"
_roll = 1706256
# public member function
def displayNameAndRoll(self):
# accessing protected data members
print("Name: ", self._name)
print("Roll: ", self._roll)
# creating objects of the class
obj = Geek()
# calling public member
# functions of the class
obj.displayNameAndRoll()
Name: R2J Roll: 1706256Example 2: During Inheritance
# program to illustrate protected
# data members in a class
# super class
class Shape:
# constructor
def __init__(self, length, breadth):
self._length = length
self._breadth = breadth
# public member function
def displaySides(self):
# accessing protected data members
print("Length: ", self._length)
print("Breadth: ", self._breadth)
# derived class
class Rectangle(Shape):
# constructor
def __init__(self, length, breadth):
# Calling the constructor of
# Super class
Shape.__init__(self, length, breadth)
# public member function
def calculateArea(self):
# accessing protected data members of super class
print("Area: ", self._length * self._breadth)
# creating objects of the
# derived class
obj = Rectangle(80, 50)
# calling derived member
# functions of the class
obj.displaySides()
# calling public member
# functions of the class
obj.calculateArea()
Length: 80 Breadth: 50 Area: 4000In the above example, the protected variables
_length and _breadth of the super class Shape are accessed within the class by a member function displaySides() and can be accessed from class Rectangle which is derived from the Shape class. The member function calculateArea() of class Rectangle accesses the protected data members _length and _breadth of the super class Shape to calculate the area of the rectangle.
