Python Constructors

A Constructor is a special method that is automatically called when an object is created. In Python, the constructor is defined using the __init__() method.

Constructors are mainly used to initialize object attributes.

Default Constructor

A constructor that does not accept any additional parameters is called a default constructor.

Example

class Student:
    def __init__(self):
        print("Constructor Called")

student = Student()

Output:

Constructor Called

Parameterized Constructor

A constructor that accepts parameters is called a parameterized constructor.

Example

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

student = Student("John", 20)

print(student.name)
print(student.age)

Output:

John
20

Constructor with Default Values

Example

class Student:
    def __init__(self, name="Guest"):
        self.name = name

student1 = Student()
student2 = Student("Alice")

print(student1.name)
print(student2.name)

Output:

Guest
Alice

Using Constructor with Methods

Example

class Student:
    def __init__(self, name):
        self.name = name

    def show(self):
        print("Student Name:", self.name)

student = Student("John")

student.show()

Output:

Student Name: John

Multiple Object Creation

Example

class Student:
    def __init__(self, name):
        self.name = name

student1 = Student("John")
student2 = Student("Alice")

print(student1.name)
print(student2.name)

Output:

John
Alice

Constructor with Calculations

Example

class Rectangle:
    def __init__(self, length, width):
        self.area = length * width

rectangle = Rectangle(10, 5)

print(rectangle.area)

Output:

50

Constructor Inheritance Example

Example

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

class Student(Person):
    pass

student = Student("John")

print(student.name)

Output:

John

Summary

• Constructors are special methods used to initialize objects.
• Python uses the __init__() method as a constructor.
• Constructors are called automatically when an object is created.
• Constructors can accept parameters.
• Default values can be provided in constructors.
• Constructors help initialize object attributes.
• Every object gets its own set of initialized values.