auto-typing-final
Auto-fixer for Python code that adds typing.Final annotation to variable assignments inside functions that are not reassigned, and removes the annotation from variables that are mutated.
def foo() -> None:
- a = 2
+ a: typing.Final = 2
- b: typing.Final = 2
+ b = 2
b = 3
Basically, this, but handles different operations (like usage of nonlocal, augmented assignments: +=, etc) as well.
- Keeps type checker happy.
- Adds global import if it's not imported yet (
import typing/from typing import Final).
- Inspects one file at a time.
- Is careful with global variables: adds Final only for uppercase variables, ignores variable that are referenced in
global statement inside functions in current file, and avoids removing Final when it already was set (docs).
- Ignores class variables: it is common to use
typing.ClassVar instead of typing.Final.
How To Use
Having uv installed:
uvx auto-typing-final .
or:
pipx run auto-typing-final .
Options
You can specify --check flag to check the files instead of actually fixing them:
auto-typing-final . --check
Also, you can choose import style from two options: typing-final (default) and final:
auto-typing-final . --import-style typing-final
typing-final enforces import typing and typing.Final,final enforces from typing import Final and Final.
Also, you can set --ignore-global-vars flag to ignore global variables:
auto-typing-final . --ignore-global-vars
You can ignore variables by adding # auto-typing-final: ignore comment to the line (docs).
VS Code Extension
The extension uses LSP server bundled with the CLI (executable name is auto-typing-final-lsp-server). To get started, add auto-typing-final to your project:
uv add auto-typing-final --dev
After that, install the extension: https://marketplace.visualstudio.com/items?itemName=vrslev.auto-typing-final. In Python environments that have auto-typing-final installed, extension will be activated automatically.
Settings
- Import style can be configured in settings:
"auto-typing-final.import-style": "typing-final" or "auto-typing-final.import-style": "final".
- Ignore global variables can be configured in settings:
"auto-typing-final.ignore-global-vars": true.
Notes
Library code of currently activated environment will be ignored (for example, .venv/bin/python is active interpreter, all code inside .venv will be ignored).
