gh-127124: Pass optional state to context watcher callback

rhansen commented 3 days ago

This enables users to associate state with the callback without relying on globals.

Also:

Refactor the tests for improved readability and extensibility, and to cover the new state object.
Drop the pointer from the PyContext_WatchCallback typedef. This de-obfuscates the fact that pointers are involved, and makes it possible to forward-declare functions to improve readability:
```
static PyContext_WatchCallback my_callback;

int
my_callback(PyObject *cbarg, PyContextEvent event, PyObject *obj)
{
    ...
}
```

This will conflict with #124741; if one is merged I'll rebase the other.

Issue: gh-127124

📚 Documentation preview 📚: https://cpython-previews--127140.org.readthedocs.build/

ZeroIntensity commented 1 day ago

FWIW, no need to force push changes--it makes reviewing harder. It's fine to just commit normally, and then everything gets squashed.

rhansen commented 15 hours ago

Force pushing is the only way to update the commit message.

ZeroIntensity commented 10 hours ago

Yes, but it makes reviewing more difficult. FWIW, nobody really cares about the commit messages in the PR itself, the end message that gets squashed is really what matters. (There's a section in the devguide about this, IIRC.)

python / cpython

gh-127124: Pass optional state to context watcher callback #127140