Hacktoberfest 2026: the issues maintainers tagged for October, open and beginner-friendly. Browse Hacktoberfest issues

Specify what happens for binary operators (e.g. `__add__`)

Open
#1,548 8 comments 1 reaction 0 assignees View on GitHub

Nobody has claimed this yet.

Assessment

Difficulty
5/5
Estimated time
Over a week
Newbie friendliness
25/100
Issue type
Documentation
Clarity
Needs clarification
Activity status
Stale
Tech stack
python
Domain
documentation

Research direction

Start by reviewing the language-specification rules for add, radd, eq, and NotImplemented, then compare how typeshed currently represents these methods. Check how typecheckers handle concrete implementations that can return NotImplemented. Done means reaching agreement on the signatures and behavior that should be specified.

Written by the indexing model from the issue text.

Description

topic: typing spec

There's a subtle dance around __add__, __radd__, and NotImplemented. While most of the rules are in the language spec, I think we haven't specified carefully what the signature should be of e.g. the __add__ method, especially when annotations are inline. (At least, I didn't find any mention of NotImplemented in the spec.)

In typeshed we seem to ignore the "overload" __add__: (Any) -> Literal[NotImplemented] (to be loose with notation), but what do typecheckers do when they see a concrete __add__ or __eq__ implementation that can return NotImplemented?

Dominant language
Python
Stars
1.8k
Forks
302
Avg merge
23h
Merged PRs (30d)
8

Contributor guide

No contributing guide indexed for this repository

First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

More from python/typing

All issues in python/typing

Similar issues

More Python issues

Get new issues in your inbox

A short digest of beginner-friendly GitHub issues.