Clean Code in Python/

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Creating Classes with a More Compact Syntax

Creating Classes with a More Compact Syntax

Learn how to make use of dataclasses decorator to create classes with compact syntax.

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Let's continue with the idea that sometimes, we need objects to hold values. There's a common boilerplate in Python when it comes to the initialization of objects, which is to declare in the __init__ method all attributes that the object will have, and then set that to internal variables, typically in this form:

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def __init__(self, x, y, ...):
    self.x = x
    self.y = y

The dataclasses module

Ever since Python 3.7 was released, we can simplify this by using the dataclasses module.

The @dataclass decorator

This module provides a @dataclass decorator, which, when applied to a class, will take all the class attributesThese are attributes shared by all instances of a class. with annotations and treat them as instance attributesThese are attributes attached to a specific instance of a class., as if they were declared in the initialization method. When using this decorator, it will automatically generate the __init__ method on the class, so we don't have to.

The field object

Additionally, this module provides a field object that will help us define particular traits for some of the attributes. For example, if one of the attributes we need needs to be mutable (such as a list), we cannot pass this default empty list in the __init__ method. Instead we should pass None, and set it to a default list inside __ ...