Internal Docs

Here you can find:

  1. How our development process works
  2. How to contribute to the project
  3. How to write new rules
  4. How our internal API looks like

This information will also be helpful if you would like to create our own flake8 plugin.

How to read this documentation

You will need to start from the glossary where we define the terms for this project.

Then move to the contributing guide where we specify all technical details about our workflow and tools.

Then you will be ready to dive into our “Creating a new rule tutorial”.

And finally you will need to go through the API reference to cover specific technical questions you will encounter.


  1. Done is better than perfect
  2. However, we pursuit perfect software
  3. False negatives over false positives
  4. If you can not sustain your promise - do not promise
  5. Code must be written for people to read, and only incidentally for machines to execute
  6. Value consistency over syntax-ish readability
  7. Consistent code is more readable then inconsistent
  8. Do not force people to choose, they will make mistakes
  9. Made choices must be respected


This schema should give you a brief overview of what is happening inside our linter. This is a very simplified architecture that will help you to understand how all components are bound together.

sequenceDiagram participant flake8 participant Checker participant Transformation participant Visitor participant Violation flake8->>Checker: flake8 runs our checker alongside with other plugins Checker->>Transformation: Checker asks to perform different ast transformations before we actually start doing anything Checker->>Visitor: Checker runs all visitors that it is aware of Visitor->>Violation: Visitors raise violations when they find bad code Violation-->>flake8: Raised violations are shown to user by flake8

Architecture overview.

We use a layered architecture that follows this contract:

Linting process:
    - wemake_python_styleguide
    - checker
    - transformations
    - presets
    - visitors
    - violations
    - logics
    - options


Creating a new rule

This tutorial will guide you through the whole process of creating new rules for this linter.

API Reference

Raw technical information with interface and types declarations, featuring architecure and composition of classes.