Public, Private & Protected Access Specifiers | Python Tutorials For Absolute Beginners In Hindi #63

In high-level programming languages like C++, Java, etc., private, protected and public keywords are used to control the access of class members or variables. However, Python has no such keywords. Python uses a convention of prefixing the name of the variable or method with a single underscore(_) or double underscore(__) to emulate the behaviour of protected and private access specifiers.

Access modifiers are used for the restrictions of access any other class has on the particular class and its variables and methods. In other words, access modifiers decide whether other classes can use the variables or functions of a specific class or not. The arrangement of private and protected access variables or method ensures the principle of data encapsulation. In Python, there are three types of access modifiers.

• Public Access Modifier
• Protected Access Modifier
• Private Access Modifier

Public Access Modifier:

In public, all the functions, variables, methods can be used publicly. Meaning, every other class can access them easily without any restriction. Public members are generally methods declared in a class that is accessible from outside the class. Any ordinary class is by default, a public class. So, all the classes we had made till now in the previous tutorials were all public by default.

Example of public access modifier:

class employee:
      def __init__(self, name, age):
            self.name=name
            self.age=age

Protected Access Modifier:

In case of a protected class, its members and functions can only be accessed by the classes derived from it, i.e. its child class or classes. No other environment is permitted to access it. To declare a class as protected, we use a single underscore “_” sign before the data members of the class.

Example of protected access modifier:

class employee:
      def __init__(self, name, age):
            self._name=name # protected attribute 
            self._age=age # protected attribute

Private Access Modifier:

In the case of private access modifiers, the variables and functions can only be accessed within the class. The private restriction level is the highest for any class. To declare a class as private, we use a double underscore “_­_” sign before the data members of the class. Here is a suggestion to not try to access private variables from outside the class, because it will result in an AttributeError. 

Example of private access modifier:

class employee:
      def __init__(self, name, age):
            self.__name=name # private attribute 
            self.__age=age # private attribute

Name mangling in Python:

Python does not have any strict rules when it comes to public, protected or private, like java. So, to protect us from using the private attribute in any other class, Python does name mangling, which means that every member with a double underscore will be changed to _object._class__variable when trying to call using an object. The purpose of this is to warn a user, so he does not use any private class variable or function by mistake without realizing it's states.

The use of single underscore and double underscore is just a way of name mangling because Python does not take the public, private and protected terms much seriously so we have to use our naming conventions by putting single or double underscore to let the fellow programmers know which class they can access or which they can't.

Code as described/written in the video

# Public -
# Protected -
# Private -

class Employee:
    no_of_leaves = 8
    var = 8
    _protec = 9
    __pr = 98

    def __init__(self, aname, asalary, arole):
        self.name = aname
        self.salary = asalary
        self.role = arole

    def printdetails(self):
        return f"The Name is {self.name}. Salary is {self.salary} and role is {self.role}"

    @classmethod
    def change_leaves(cls, newleaves):
        cls.no_of_leaves = newleaves

    @classmethod
    def from_dash(cls, string):
        return cls(*string.split("-"))

    @staticmethod
    def printgood(string):
        print("This is good " + string)

emp = Employee("harry", 343, "Programmer")
print(emp._Employee__pr)