Expose logging levels

[WaDelma]

I am using FromStr implementation of LevelFilter to parse logging level given by user via command line flag. In case user gives invalid logging level I want to print list of allowed values. Currently I have to replicate LOG_LEVEL_NAMES array in my code and remember to keep it in sync (It is probably unlikely it changes that much though).

One question I have is that is there a reason it is static instead of const?

[KodrAus]

Hey @WaDelma 👋

There probably isn't a great reason for this to be static rather than const. Rather than make the array public though I think a static method on Level that returns some impl Iterator<Item = Level> might be better:

pub fn iter_all() -> impl Iterator<Item = Level> {
    ..
}

That way in your code you could call something like:

let names = Level::iter_all().map(|l| l.as_str()).collect();

The reason I think we should avoid making the array public is that it would be a breaking change to add any more levels (as unlikely as that is) because the type would change from [&'static str; 6] to [&'static str; 7].

[WaDelma]

Makes sense. I added such static methods for both Level and LevelFilter,

[KodrAus]

It might be worth documenting something about the order of these fields. Using from_usize we’re effectively returning them in priority order.

What do you think?

[KodrAus]

Thanks for working on this @WaDelma!