From: "Andreas Hindborg (Samsung)" <nmi@metaspace.dk>
To: Alice Ryhl <aliceryhl@google.com>
Cc: alex.gaynor@gmail.com, benno.lossin@proton.me,
bjorn3_gh@protonmail.com, boqun.feng@gmail.com, gary@garyguo.net,
linux-kernel@vger.kernel.org, ojeda@kernel.org,
patches@lists.linux.dev, rust-for-linux@vger.kernel.org,
wedsonaf@gmail.com
Subject: Re: [PATCH v1] rust: add improved version of `ForeignOwnable::borrow_mut`
Date: Wed, 23 Aug 2023 10:40:54 +0200 [thread overview]
Message-ID: <87r0nu40cs.fsf@metaspace.dk> (raw)
In-Reply-To: <20230822093148.3478340-1-aliceryhl@google.com>
Alice Ryhl <aliceryhl@google.com> writes:
> Andreas Hindborg <nmi@metaspace.dk> writes:
>>> + /// Borrows a foreign-owned object mutably.
>>> + ///
>>> + /// This method provides a way to access a foreign-owned value from Rust mutably. It provides
>>> + /// you with exactly the same abilities as an `&mut Self` when the value is Rust-owned, except
>>> + /// that this method does not let you swap the foreign-owned object for another. (That is, it
>>> + /// does not let you change the address of the void pointer that the foreign code is storing.)
>>
>> How about this:
>>
>> "For a smart pointer P<T> this method provides mutable access to T if
>> &mut P<T> would allow mutable access to T. Otherwise it provides
>> immutable access to T."
>>
>> The point is that the method provides access to the pointee, not the
>> smart pointer itself. In fact it is perfectly fine to do a mem::swawp()
>> for the pointee in the case of Box and depending on interpretation the
>> sentence "does not let you swap the foreign-owned object for another" is
>> confusing.
>
> Yeah, I agree that the phrasing is somewhat confusing.
>
> How about this:
>
> /// This method provides a way to access a foreign-owned value from Rust mutably. It provides
> /// you with exactly the same abilities as an `&mut Self` when the value is Rust-owned, except
> /// that the address of the object must not be changed.
> ///
> /// Note that for types like [`Arc`], an `&mut Arc<T>` only gives you immutable access to the
> /// inner value, so this method also only provides immutable access in that case.
> ///
> /// In the case of `Box<T>`, this method gives you the ability to modify the inner `T`, but it
> /// does not let you change the box itself. That is, you cannot change which allocation the box
> /// points at.
Sounds good 👍
BR Andreas
next prev parent reply other threads:[~2023-08-23 8:41 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-07-10 7:46 [PATCH v1] rust: add improved version of `ForeignOwnable::borrow_mut` Alice Ryhl
2023-07-11 17:42 ` Boqun Feng
2023-07-14 10:28 ` Alice Ryhl
2023-07-13 3:28 ` Martin Rodriguez Reboredo
2023-07-15 13:38 ` Benno Lossin
2023-08-09 14:09 ` Andreas Hindborg (Samsung)
2023-08-22 9:31 ` Alice Ryhl
2023-08-23 8:40 ` Andreas Hindborg (Samsung) [this message]
2023-08-22 9:31 ` Alice Ryhl
2023-08-23 8:43 ` Andreas Hindborg (Samsung)
2023-08-23 10:34 ` Alice Ryhl
2023-08-23 16:09 ` Andreas Hindborg (Samsung)
2023-10-25 12:22 ` Ariel Miculas (amiculas)
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