add Bound constructor for PyBool

[Icxolu]

Part of #3684

This adds the Bound constructors for PyBool.

Since the ffi types Py_True and Py_False are singletons pointing into static memory, this return Borrowed instead of Bound. I choose to still keep the name new_bound for consistency with the other type. Since Borrowed derefs into &Bound it also behaves very similarly.

[davidhewitt]

Thank you yet again 👍

I'm a bit under the weather this evening so I'll do my best to read and review first thing in the morning.

[davidhewitt]

Thanks, this looks like the right design to me! I think the __ne__ implementation probably needs to create a "new reference" using .to_owned(), otherwise I have mostly just added comments of approval and very tiny nits.

[davidhewitt]

Thanks again, looks good to me!

We're getting pretty close to having this API be feature-complete now! I think there will still be a long tail of adjustments and refactoring, but users can hopefully start playing with this before long 🚀

[adamreichold]

Sorry for being late to the party: If these are singletons, shouldn't the first lifetime even be 'static, i.e.

pub fn new_bound(py: Python<'py>, val: bool) -> Borrowed<'static, 'py, Self>;

or are they still bound to the interpreter?

[davidhewitt]

I wondered about this, I think while static is possibly fine I preferred having this limited to the interpreter. Just in case this becomes relevant for things like subinterpreters in the future.

[davidhewitt]

I guess we can always expand this later if users have a need.

[Icxolu]

I thought about this too, but it seemed safer to go with this option now, and relax it in the future if possible.