PyO3/pyo3

Seal traits inside `impl_` submodule

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#3,908 opened on Feb 27, 2024

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 (13 comments) (0 reactions) (0 assignees)Rust (10,152 stars) (668 forks)batch import
Good First Issue

Description

Off the back of https://github.com/PyO3/pyo3/pull/3897#discussion_r1504721475

Should we review the traits inside the impl_ submodule, check which ones can be sealed, and do that? It's a reasonable safety mechanism to prevent users from trying to implement those things.

Contributor guide

Tech stack
rust
Domain
backenddeveloper experience
Issue type
feature
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
half day
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
active
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
clear
Prerequisites
Knowledge of Rust's sealed trait patternFamiliarity with PyO3's `impl ` submodule
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
45
Research direction
Start by examining the `impl ` submodule in the pyo3 crate's source code. Review the discussion in PR #3897, especially the comment at the linked line, to understand which traits are candidates for sealing. Then, implement a private sealed trait marker (e.g., a hidden supertrait) and modify the trait definitions in the `impl ` submodule to require that marker. Ensure that the sealing does not break existing functionality and is backward compatible. The issue does not specify all traits to seal, so you may need to propose a list and get feedback from maintainers.