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The “attrs” library is an open-source Python library that provides a concise way to define classes with automatically generated special methods, such as __init__, __repr__, and __eq__. It was created by Hynek Schlawack and is hosted on GitHub.

The main goal of the “attrs” library is to reduce boilerplate code when defining classes by automating the creation of commonly used methods. It achieves this by using a class decorator and a simple declarative syntax. The library is often used for creating lightweight data classes or value objects.

Key features and concepts of the “attrs” library include:

  1. Class Decorator: The @attrs decorator is applied to a class definition to enable the automatic generation of special methods based on class attributes.
  2. Attribute Definition: Class attributes are defined using the attr.ib decorator within the class body. These attributes represent the data that will be stored in instances of the class.
  3. Special Method Generation: By using the @attrs decorator, the “attrs” library generates various special methods automatically, such as __init__, __repr__, __eq__, and __hash__. These methods provide common functionality like initialization, string representation, equality checking, and hashing.
  4. Attribute Validation and Conversion: The “attrs” library allows you to specify validators and converters for attributes. Validators can be used to enforce constraints on attribute values, while converters allow you to transform input values before assigning them to attributes.
  5. Additional Features: “attrs” provides other features, such as default values for attributes, support for inheritance, and options to customize the behavior of generated methods.

By using the “attrs” library, you can define classes more concisely and focus on the actual data and behavior of your objects rather than writing repetitive code for special methods.

The “attrs” library is well-documented, and you can find more information, usage examples, and installation instructions on the official GitHub repository at

References / discussions

Page last modified: 2023-05-11 17:27:39