flake8-trio 22.7.6

A highly opinionated flake8 plugin for Trio-related problems.

flake8-trio

A highly opinionated flake8 plugin for Trio-related problems.

This can include anything from outright bugs, to pointless/dead code, to likely performance issues, to minor points of idiom that might signal a misunderstanding.

It may well be too noisy for anyone with different opinions, that's OK.

Pairs well with flake8-async and flake8-bugbear.

Installation

pip install flake8-trio

List of warnings

• TRIO100: a with trio.fail_after(...): or with trio.move_on_after(...): context does not contain any await statements. This makes it pointless, as the timeout can only be triggered by a checkpoint.
• TRIO101: yield inside a nursery or cancel scope is only safe when implementing a context manager - otherwise, it breaks exception handling.
• TRIO102: it's unsafe to await inside finally: or except BaseException/trio.Cancelled unless you use a shielded cancel scope with a timeout.
• TRIO103: except BaseException and except trio.Cancelled with a code path that doesn't re-raise. Note that any raise statements in loops are ignored since it's tricky to parse loop flow with break, continue and/or the zero-iteration case.
• TRIO104: Cancelled and BaseException must be re-raised - when a user tries to return or raise a different exception.
• TRIO105: Calling a trio async function without immediately awaiting it.
• TRIO106: trio must be imported with import trio for the linter to work.
• TRIO107: Async functions must have at least one checkpoint on every code path, unless an exception is raised.
• TRIO108: Early return from async function must have at least one checkpoint on every code path before it, unless an exception is raised. Checkpoints are await, async with async for.

Changelog

CalVer, YY.month.patch

22.7.6

• Extend TRIO102 to also check inside except BaseException and except trio.Cancelled
• Extend TRIO104 to also check for yield
• Update error messages on TRIO102 and TRIO103

22.7.5

• Add TRIO103: except BaseException or except trio.Cancelled with a code path that doesn't re-raise
• Add TRIO104: "Cancelled and BaseException must be re-raised" if user tries to return or raise a different exception.
• Added TRIO107: Async functions must have at least one checkpoint on every code path, unless an exception is raised
• Added TRIO108: Early return from async function must have at least one checkpoint on every code path before it.

22.7.4

• Added TRIO105 check for not immediately awaiting async trio functions.
• Added TRIO106 check that trio is imported in a form that the plugin can easily parse.

22.7.3

• Added TRIO102 check for unsafe checkpoints inside finally: blocks

22.7.2

• Avoid TRIO100 false-alarms on cancel scopes containing async for or async with.

22.7.1

• Initial release with TRIO100 and TRIO101