Sentry Answers>Python>

`super()` and `__init__()` in Python

`super()` and `__init__()` in Python

David Y.

The ProblemJump To Solution

What does super() refer to in Python and why is it often used in __init__() methods?

The Solution

In Python, super() is a built-in function used to call methods defined in the parent class. One of the advantages of inheritance in an object-oriented language like Python is avoiding code duplication. Consider the following code:

Click to Copy
MARKUP = 1.5 class Product: def __init__(self, name, cost_price): = name self.cost_price = cost_price self.selling_price = cost_price * MARKUP class Perishable(Product): def __init__(self, name, cost_price, shelf_life): super().__init__(name, cost_price) self.shelf_life = shelf_life

The line starting with super().__init__ will execute the __init__ method of Product as if it were a method defined in Perishable. This saves us from having to rewrite our pricing code in every child class of Product. Whenever we create an instance of Perishable, it will have a name, cost_price, selling_price, and shelf_life.

In this example, we could replace super().__init__ with Product.__init__ and achieve the same thing, but super() allows us to write more general code and is necessary for more complex class hierarchies that use dependency injection and multiple inheritance.

In Python 2 code and older Python 3 code, you may encounter lines written like this:

Click to Copy
super(Perishable, self).__init__(name, cost_price)

This is equivalent to calling super() in Python 3. While it is more explicit and was the required way to use super() in Python 2, it is no longer necessary, will slow down our code, and should thus be avoided.

  • Sentry BlogPython Performance Testing: A Comprehensive Guide
  • Sentry BlogLogging in Python: A Developer’s Guide
  • logo
    Listen to the Syntax Podcast

    Tasty Treats for Web Developers brought to you by Sentry. Web development tips and tricks hosted by Wes Bos and Scott Tolinski

    Listen to Syntax

Loved by over 4 million developers and more than 90,000 organizations worldwide, Sentry provides code-level observability to many of the world’s best-known companies like Disney, Peloton, Cloudflare, Eventbrite, Slack, Supercell, and Rockstar Games. Each month we process billions of exceptions from the most popular products on the internet.

© 2024 • Sentry is a registered Trademark
of Functional Software, Inc.