Encapsulation

Encapsulation is related to a concept of information hiding. By following the practices of encapsulation, we can restrict the access to the classes/objects’ certain attributes and methods.

Why Encapsulation?

Encapsulation's main purpose is to bundle data/attribute with the methods that operate on that data. Encapsulation is used to hide the values or state of a structured data object inside a class, preventing unauthorized parties’ direct access to them.

Encapsulation within Custom Python Objects

To encapsulate attributes or methods in Python, we use the __ prefix. (Double Underscoring)

# Example
class Car:
    def __init__(self, make, model, year):
        self.make = make
        self.model = model
        self.year = year
        self.__mileage = 0 # mileage is encapsulated

    def start_engine(self):
        print(f"The {self.make} {self.model}'s engine is now running.")

    def stop_engine(self):
        print(f"The {self.make} {self.model}'s engine has been stopped.")
    
    def get_mileage(self):
        return self.__mileage
    
    def increase_mileage(self, amount):
        self.__mileage += amount
    
    def __reset_mileage(self): # reset_mileage() method is encapsulated
        self.__mileage = 0
# end of car class

If you examine the Car class, we have 1 new attribute and 3 new methods.

• Our new attribute: mileage is encapsulated. Therefore, we cannot access the value out side of the class definition.

• Since mileage is encapsulated, it is often a common practice to write a getter method to be able to grab hidden data. The method is designed to grab encapsulated data in a controlled and safe way. (Example: get_mileage())

• When you want to design methods that you don't want objects to have access to, but you want your class definition to have access, you can also encapsulate methods with double underscoring as well. (Example: __reset_mileage())