Const accessing speed

[dmitriyzimin]

Does const accessing speed (const EX: Ex = Ex::new()) is faster than it dynamic creating and accessing?

[kornel]

Purely for access, there shouldn't be a major difference either way. As a microoptimization, there's no general rule, because it depends on the context and what the optimizer can do.

But if you're trying to optimize code by adding const everywhere, it may be a bad idea. It may make code more bloated, because it will create a new copy of the const value every time it's used. This can also lead to surprising behavior and bugs.

const items are not behaving like let variables:

fn main() {
    let a = b + 1;
    const b: i32 = 2;
}

fn main() {
    const vec: Vec<u8> = Vec::new();
    vec.push(1);
    assert!(vec.is_empty());
}

[dmitriyzimin]

Thanks for the explanation.