Discussion of `..` pattern does not demo slices nor the idiom `[a, b, middle @ .., y, z]`

[pnkfelix]

• I have checked the latest main branch to see if this has already been fixed
• I have searched existing issues and pull requests for duplicates

URL to the section(s) of the book with this problem:

https://doc.rust-lang.org/stable/book/ch18-03-pattern-syntax.html#ignoring-remaining-parts-of-a-value-with-

Description of the problem:

The discussion of .. shows how to use .. to "ignore" things, and demonstrates it on struct patterns and tuple patterns.

But the book does not show .. in use on slice patterns.

Nor does it demonstrate the (common?) idiom of not ignoring the portion of the slice matched via .., but instead binding it to its own variable, via the pattern IDENT @ .. in the midst of the slice pattern.

Suggested fix:

To be honest, I'm not totally sure. It would be fine to fix the absence of slice demos by just adding one.

But the "Ignoring Values in a Pattern" would be a bit of a weird place to show how not to ignore it. That's what I'm hestiating about. :)

[pnkfelix]

For reference, subslice patterns became stable in Rust 1.42.

[mumbleskates]

This is a feature I wasn't entirely aware of until rather later than I would have been, mostly due to its omission here in chapter 18. It's been 4.5 years since ident @ .. matching in slice patterns was stabilized, and it would be lovely to have an example of this in the general guidance for matching and destructuring values.