Tracking Issue for `array::repeat`

[joboet]

Feature gate: #![feature(array_repeat)]

This is a tracking issue for array::repeat, a function for creating array filled with a single Cloneable value.

Public API

// core::array

pub fn repeat<T: Clone, const N: usize>(v: T) -> [T; N];

Steps / History

• ACP: Add array::repeat for making an array from a non-Copy non-const value libs-team#310
• Implementation: Implement array::repeat #119127
• Final comment period (FCP)¹
• Stabilization PR

Unresolved Questions

• None yet.

Footnotes

1. https://std-dev-guide.rust-lang.org/feature-lifecycle/stabilization.html ↩

[scottmcm]

Hi libs-api! It's been 13 months since this landed, so I figured I'd suggest it be given stabilization consideration.

Basically, I think we should have a direct thing to suggest to anyone who does something like [my_string; 4] so they don't need to do a ask on Discord.

And TBH the current answers aren't amazing even if you know them, because while array::from_fn(|_| my_string.clone()) isn't bad it's one clone more than needed. And something like let mut it = iter::repeat_n(my_string, 4); array::from_fn(|_| it.next().unwrap()) isn't what I'd call nice.

Plus I'd sometimes be tempted to use it even if [;] would work, like <$ty>::from_be_bytes(repeat(0x80)) is rather nice.

[Amanieu]

@rfcbot merge

[rfcbot]

Team member @Amanieu has proposed to merge this. The next step is review by the rest of the tagged team members:

• @Amanieu
• @BurntSushi
• @dtolnay
• @joshtriplett
• @m-ou-se

No concerns currently listed.

Once a majority of reviewers approve (and at most 2 approvals are outstanding), this will enter its final comment period. If you spot a major issue that hasn't been raised at any point in this process, please speak up!

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