# Python super() and __init__() Explained in Detail

> Use super().__init__() in a Python subclass to call the parent class constructor without duplicating code, avoiding the older Python 2 super(Class, self) syntax

**URL:** https://sentry.io/answers/super-and-init-in-python/

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## The Problem

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:

```python
MARKUP = 1.5

class Product:
    def __init__(self, name, cost_price):
        self.name = 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](https://medium.com/@suneandreasdybrodebel/pythonic-dependency-injection-a-practical-guide-83a1b1299280) and [multiple inheritance](https://realpython.com/lessons/multiple-inheritance-python/).

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

```python
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.

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*Source: [sentry.io/answers/super-and-init-in-python/](https://sentry.io/answers/super-and-init-in-python/)*