Utility of `take_if`?

1

Rust 1.80 released take_if.

What are the biggest use cases? Or what's the backstory to why this was introduced? Which pain does it solve?

2

For the history, see Add `Option::retain` · Issue #70 · rust-lang/libs-team · GitHub and Add `Option::take_if` · Issue #98934 · rust-lang/rust · GitHub

1 Like
3

Here's the problem statement:

fn some_fn(values: &mut MyBigFlagStruct) {
    values.x -= 7;
    values.y += 42;

    if let Some(z) = &value.z {
        if *z < values.x * values.y {
            values.z = None;
        }
    }

    values.some_counter += 1;

    if let Some(magic) = &values.magic {
        if *magic != 42 {
           values.magic = None;
        }
    }
}

What are some real-world scenarios where this situation would occur? In my experience it seems like a rather uncommon situation, but perhaps it may be common in other industries or types of programs than the ones I've worked with.

4

Must be values.z with an s.

5

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