Re: [PATCH 1/9] rust: list: add ListArc

[Benno Lossin <benno.lossin@proton.me>]

On 03.05.24 16:36, Alice Ryhl wrote:
> On Thu, Apr 4, 2024 at 4:00 PM Alice Ryhl <aliceryhl@google.com> wrote:
>>
>> On Wed, Apr 3, 2024 at 5:51 PM Benno Lossin <benno.lossin@proton.me> wrote:
>>>
>>> On 02.04.24 14:16, Alice Ryhl wrote:
>>>> +impl<T: ListArcSafe<ID>, const ID: u64> ListArc<T, ID> {
>>>> +    /// Constructs a new reference counted instance of `T`.
>>>> +    pub fn try_new(contents: T) -> Result<Self, AllocError> {
>>>> +        Ok(Self::from_unique(UniqueArc::try_new(contents)?))
>>>> +    }
>>>> +
>>>> +    /// Use the given initializer to in-place initialize a `T`.
>>>> +    ///
>>>> +    /// If `T: !Unpin` it will not be able to move afterwards.
>>>> +    pub fn pin_init<E>(init: impl PinInit<T, E>) -> error::Result<Self>
>>>> +    where
>>>> +        Error: From<E>,
>>>> +    {
>>>> +        Ok(Self::from_pin_unique(UniqueArc::pin_init(init)?))
>>>> +    }
>>>
>>> pin-init has a general trait for this: InPlaceInit. I don't know if the
>>> other functions that it provides would help you.
>>
>> I will use that.
> 
> Turns out it's not possible to use the trait in this case, for the
> same reasons as why Arc isn't using them either.

Ugh that is annoying, I think we can change `InPlaceInit` to have a
`PinnedSelf` associated type. I will create a good-first-issue.

-- 
Cheers,
Benno