linux-kernel - Re: [PATCH 03/10] rust: xarray: add `contains

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Message-ID: <CAJ-ks9kYk7cuQFOK89OwUx+k8p+_kANjB12rZLO+dzfSd=BpdQ@mail.gmail.com>
Date: Wed, 7 Jan 2026 13:38:05 -0500
From: Tamir Duberstein <tamird@...il.com>
To: Andreas Hindborg <a.hindborg@...nel.org>
Cc: Miguel Ojeda <ojeda@...nel.org>, Alex Gaynor <alex.gaynor@...il.com>, 
	Boqun Feng <boqun.feng@...il.com>, Gary Guo <gary@...yguo.net>, 
	Björn Roy Baron <bjorn3_gh@...tonmail.com>, 
	Benno Lossin <lossin@...nel.org>, Alice Ryhl <aliceryhl@...gle.com>, 
	Trevor Gross <tmgross@...ch.edu>, Danilo Krummrich <dakr@...nel.org>, Daniel Gomez <da.gomez@...nel.org>, 
	rust-for-linux@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 03/10] rust: xarray: add `contains_index` method

On Wed, Jan 7, 2026 at 1:34 PM Andreas Hindborg <a.hindborg@...nel.org> wrote:
>
> Tamir Duberstein <tamird@...il.com> writes:
>
> > On Wed, Dec 3, 2025 at 5:27 PM Andreas Hindborg <a.hindborg@...nel.org> wrote:
> >>
> >> Add a convenience method `contains_index` to check whether an element
> >> exists at a given index in the XArray. This method provides a more
> >> ergonomic API compared to calling `get` and checking for `Some`.
> >
> > It isn't clear when you'd want this API, and neither this nor the
> > example are particularly motivating.
>
> I added this when I had a line reading `if xa.get(index).is_none()
> {...}`. I think it reads better as `if !xa.contains_index(index) {...}`.

What was the code surrounding it?

> Do you have an idea of how to improve the motivational factor of the
> example? Writing motivating examples is not my top skill.

IMO writing a better example is not the issue; rather it would be good
to understand why you need it. In my experience `Option::is_none` is a
smell, but hard to say without seeing the surrounding code.

> Best regards,
> Andreas Hindborg
>
>