Constructor in Python

In object-oriented programming (OOP), a Constructor is a special method that is automatically called when an object of a class is created. Its primary purpose is to initialize the attributes or properties of the object. Constructors ensure that an object starts with a known state and can be used immediately after its creation.

In Python, constructors are defined using a method named __init__. This method is automatically invoked when an object of the class is instantiated. It allows you to initialize attributes and perform any setup required for the object to function correctly.

 In the below PDF we discuss about Constructor in detail in simple language, Hope this will help in better understanding.


Types of Constructors:

Python supports two types of constructors:

  1. Default Constructor:                      If you do not explicitly define a constructor in your class, Python provides a default constructor with no parameters. It initializes the object but does not perform any custom initialization.

class MyClass:
def __init__(self):
print("Default constructor called")

obj = MyClass() # Creates an object of MyClass and calls the default constructor

  1. Parameterized Constructor:  You can create constructors that accept parameters to customize the initialization of objects based on specific values.

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

person1 = Person("Alice", 30)
person2 = Person("Bob", 25)

In this example, we have a Person class with a parameterized constructor that accepts name and age as arguments. When creating objects of this class, we pass these values to the constructor.

Use of Constructors:

  • Initialize Attributes: Use the constructor to set initial values for the object’s attributes. This ensures that objects start with the desired state.
  • Validation: You can include validation logic in the constructor to check if the provided values are valid. This helps maintain data integrity.
  • Default Values: Provide default values for constructor parameters if they are optional. This allows users to create objects with minimal input.
  • Document Your Constructors: As with any code, it’s important to add comments or docstrings to describe what the constructor does and what parameters it accepts. This helps other developers understand how to use your classes.
  • Multiple Constructors: Python does not support method overloading like some other languages, but you can achieve similar functionality by using default parameter values or defining multiple constructors with different parameter lists.

Related Question

A constructor in Python is a special method that gets automatically called when an object of a class is created. It is used to initialize the attributes or properties of the object.

In Python, the constructor is defined using the __init__ method within a class. It takes self as its first parameter, which refers to the instance being created, and can also take additional parameters to initialize object attributes.

The main purpose of a constructor is to set the initial state of an object by initializing its attributes or performing any necessary setup operations when an object is created.

No, Python does not support multiple constructors like some other programming languages. However, you can use default parameter values or method overloading to achieve similar behavior.

You create an instance of a class with a constructor by calling the class name as if it were a function, passing any required parameters specified in the constructor.


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