Encapsulation
Encapsulation is one of the fundamental concepts of object-oriented programming (OOP), and it is implemented in Python as well as in other programming languages. Encapsulation refers to the process of hiding the internal details and implementation of an object from the outside world, while providing a simple and clear interface to interact with the object.
In Python, encapsulation can be achieved by using access modifiers, which control the visibility of the class attributes and methods. There are three types of access modifiers in Python:
- Public: Public members are accessible from anywhere in the program. In Python, all attributes and methods are public by default, and their names do not have any prefix or suffix.
- Protected: Protected members are accessible only within the class and its subclasses. In Python, protected members are indicated by a single underscore (_) prefix to the attribute or method name.
- Private: Private members are accessible only within the class. In Python, private members are indicated by a double underscore (__) prefix to the attribute or method name. However, the private members can still be accessed from outside the class by using a special syntax, which is known as name mangling.
Here is an example of encapsulation in Python:
class BankAccount:
def __init__(self, account_number, balance):
self.__account_number = account_number
self.__balance = balance
def deposit(self, amount):
self.__balance += amount
def withdraw(self, amount):
if amount > self.__balance:
print("Insufficient balance.")
else:
self.__balance -= amount
def get_balance(self):
return self.__balance
account = BankAccount("123456789", 1000)
account.deposit(500)
account.withdraw(200)
print(account.get_balance())
In this example, the BankAccount class has two private attributes, __account_number and __balance, which cannot be accessed directly from outside the class. The class also has three methods, deposit(), withdraw(), and get_balance(), which provide a simple and clear interface to interact with the object. The deposit() and withdraw() methods modify the private attribute __balance, and the get_balance() method returns the current balance of the account.
Encapsulation is an important concept in OOP because it allows us to create well-structured and maintainable code by hiding the implementation details and providing a clear and consistent interface to interact with the object.
What are constructors in Python?
In Python, a constructor is a special method that gets called automatically when an object is created from a class. It is used to initialize the attributes of the class.
In Python, the constructor method is defined with the name __init__(). It takes the self parameter, which refers to the instance of the class that is being created, as well as any other parameters that are needed to initialize the class.
Here is an example of a simple class with a constructor:
class Person:
def __init__(self, name, age):
self.name = name
self.age = age
person1 = Person("John", 25)
print(person1.name) # Output: John
print(person1.age) # Output: 25
In this example, the Person class has a constructor that takes two parameters, name and age. When an object of the Person class is created with the Person("John", 25) statement, the constructor is called automatically, and the name and age attributes of the object are set to the values that were passed in as arguments.
Note that the self parameter is always the first parameter of the constructor and all other parameters follow it. The self parameter is a reference to the instance of the class that is being created, and it is used to access the attributes and methods of that instance.
