What's the issue with having a span represent "one year and two months"? Both involve a variable number of days (365-366 and 28-31), but I would hope you could store the components separately so it can be unambiguously applied once given a specific moment in time.
I'm thinking something along the lines of how ActiveSupport::Duration works:
The components are stored separately. I think what you are advocating for is component wise addition, which I mentioned in my previous comment. It can totally "work," but as I said, it will produce different results than `span1.checked_add(span2)`. For example:
use jiff::{ToSpan, Unit, Zoned};
fn main() -> anyhow::Result<()> {
let span1 = 1.year().months(3);
let span2 = 11.months();
let now = Zoned::now().round(Unit::Minute)?;
let added = span1.checked_add((span2, &now))?;
println!("{added}");
Ok(())
}
Has this output:
$ cargo -q r
P2y2m
Notice how the months overflow automatically into years. Days will do the same into months. You need a reference point to do this correctly. For example, just `span1.checked_add(span2)?` would produce an error.
In contrast, component wise addition would lead to a span of `1 year 14 months`. Which is a valid `Span`. Jiff is fine with it. But it's different than what `checked_add` does. Having both operations seems too subtle.
Also, I don't really think using the `+` operator just to construct spans is that much of a win over what Jiff already has. So that needs to be taken into account as well.
I'm thinking something along the lines of how ActiveSupport::Duration works:
Of course the downside being that it would need to be sized large enough to contain each component, even though they may be rarely used.