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Python Constructors

17th May 2023

In this tutorial, we are going to learn Contructors in Python

In Python, a constructor is a special method that is automatically called when an object of a class is created. Constructors are used to initialize the attributes (properties) of an object. In Python, the constructor method is named __init__().

Here’s an example of a simple constructor in Python:

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

person1 = Person("Alice", 25)
print(person1.name)  # Output: Alice
print(person1.age)   # Output: 25

In the example above, we define a class called Person. The __init__() method takes three parameters: self, name, and age. The self parameter refers to the instance of the class, and it is automatically passed when an object is created. The name and age parameters are used to initialize the name and age attributes of the object.

When we create an instance of the Person class using the Person("Alice", 25) syntax, the __init__() method is automatically called with the provided arguments. The name and age attributes of the object are then initialized with the corresponding values.

You can also define default values for the constructor parameters, making them optional:

class Person:
    def __init__(self, name=None, age=None):
        self.name = name
        self.age = age

person1 = Person("Alice")
person2 = Person(age=25)
person3 = Person()

print(person1.name, person1.age)  # Output: Alice None
print(person2.name, person2.age)  # Output: None 25
print(person3.name, person3.age)  # Output: None None

In this example, we can create instances of the Person class with different combinations of provided arguments or no arguments at all. The attributes name and age will be initialized accordingly, with None as the default value if no argument is provided.

Remember that the self parameter is always required in the constructor method to refer to the instance being created.

Class,Object and Members

17th May 2023

In this tutorial we will learn Class, Object and Members in Python.

In Python, classes are used to create objects, which are instances of those classes. Classes serve as blueprints or templates for creating objects with similar characteristics and behaviors. Each object created from a class is called an instance or an object of that class.

A class defines the properties (also known as attributes) and behaviors (also known as methods) that objects of that class will have. Attributes are variables that store data, while methods are functions that define the behavior of the class.

Here’s an example of a simple class definition in Python:

class Car:
    def __init__(self, make, model, year):
        self.make = make
        self.model = model
        self.year = year

    def start_engine(self):
        print("The engine has started.")

    def drive(self):
        print("The car is being driven.")

    def stop_engine(self):
        print("The engine has stopped.")

In the above example, Car is the class, and make, model, and year are its attributes. The __init__ method is a special method called the constructor, which is executed when an instance of the class is created. It initializes the attributes of the object using the values passed as arguments.

The start_engine, drive, and stop_engine methods are behaviors associated with the Car class. They define the actions that objects of the Car class can perform.

To create an instance of the Car class, you can do the following:

my_car = Car("Toyota", "Camry", 2022)

Here, my_car is an object of the Car class. It has the attributes make (set to “Toyota”), model (set to “Camry”), and year (set to 2022). You can access the attributes and call the methods of the object using dot notation, like this:

print(my_car.make) # Output: Toyota

print(my_car.model) # Output: Camry

print(my_car.year) # Output: 2022

my_car.start_engine() # Output: The engine has started.

my_car.drive() # Output: The car is being driven.

my_car.stop_engine() # Output: The engine has stopped.

In summary, classes define the structure and behavior of objects, while objects are instances of those classes. Members refer to the attributes and methods associated with a class or an object. Attributes store data, and methods define the behaviors or actions that can be performed by the class or object.