[PATCH v5 04/23] rust: add new `num` module with `PowerOfTwo` type

[Alexandre Courbot]

On Sun Jun 15, 2025 at 10:32 PM JST, Miguel Ojeda wrote:
> On Thu, Jun 12, 2025 at 4:02 PM Alexandre Courbot <acourbot at nvidia.com> wrote:
>>
>> +                /// assert_eq!(PowerOfTwo::<u32>::try_new(16).unwrap().value(), 16);
>
> By the way, we are trying to write examples close to normal kernel
> code as possible, so could you please use `?` here instead of
> `unwrap()`?
>
> It is not a big deal, when within `assert`s, but there is value in not
> showing any `unwrap()`s, and to spot easily places where we actually
> do `unwrap()`.

The fact that `try_new` returns an `Option` makes it a bit difficult to do
nicely - one would have to add a verbose `ok_or` to turn it into a
`Result`.

But that doesn't matter as this test can be (better) written as follows:

    assert_eq!(PowerOfTwo::<u32>::try_new(16), Some(PowerOfTwo::<u32>::new(16)));

And all is well.

> Also, please use intra-doc links wherever they may work, e.g. I think
> [`PowerOfTwo`] and [`None`] will work.

Added the links where relevant, sorry for the omission!