Adding is_zero() to core::time::Duration

Hello Rust developers,

I apologize beforehand because I think this is a simple RFC, so I'm not going through full requirements of an RFC issue.

Would you please consider adding new function (below) to core::time::Duration?

/// # Checks if this duration is zero
pub fn is_zero(&self) -> bool;

When taking options from users, I find myself many times the need to check if a duration is zero. Perhaps it could be the same for other developers.

Thank you very much for your hard work,

[RustyYato]

For simple additions like this, you can just submit a pull request to get it added. But why do we need this? How would you implement this?

[jhpratt]

Though it is trivial to do with value == Duration::from_secs(0), I actually implemented this myself in the rewrite of the time crate. But I agree with @KrishnaSannasi, an RFC isn't necessary for something like this.

[CryZe]

I don't think this is sufficient motivation though. Integers, floats and co. don't have a .is_zero() either. What is this actually used for?

@CryZe

Integers can be compared to 0 easily, for example:

let flag: u8 = ...;
if flag > 0 {
    // ...
}

A Duration can't be compared to zero. Comparing a duration to zero can be useful in case the program takes input from user but doesn't allow a zero-duration.

[shepmaster]

It seems in line with the various is_empty methods already existing.

@shepmaster

Thanks for your input. is_empty() is common to collections (string, vector, set, map, slice...) While a duration is not related to a collection.

However English is not my first language, so I'm not sure.

[shepmaster]

My point was that is_zero fits in the same conceptual space as is_empty, which we use instead of len() == 0. I agree such a thing could be added.

It would be nice to find a different word besides "zero" though. We have is_empty, not is_len_zero. Unfortunately, nothing obvious is coming up.

Another possibility is creating a const ZERO: Duration = ... in the time module.

I followed full procedure and made this pull request: #2814

[jonas-schievink]

Closing this for the same reason as #2814 – it is not necessary to go through the full RFC process for this small addition.