What does it mean that a value cannot be represented by `Ratio<T>`?

[dnsl48]

What does it mean that a value cannot be represented by `Ratio`?

from fraction.

[dnsl48]

Hi @Enyium,
the FromPrimitive trait is re-imported from the num_traits crate. The documentation piece you are referring to is sourced from there.
Ratio type is also re-imported from the num_rational crate.
This crate provides GenericFraction, which implements From<f64>.

I did a few tests and transformed your explanation into the following doc comment for my Fps::from_f64() function:

sorry, I am not sure what you mean exactly, but ideally the method shouldn't panic. Semantically the method should return None if cannot convert into the relevant type.

[Enyium]

Ratio type is also re-imported from the num_rational crate. This crate provides GenericFraction, which implements From<f64>.

Thanks for the referral. Naturally I must use this crate then. I'm settling the matter with its authors.

sorry, I am not sure what you mean exactly

I'd like to specify in my API docs when exactly the method Fps::from_f64() can fail, so a lib user knows how things stand. But that depends on when my deps can fail.

ideally the method shouldn't panic. Semantically the method should return None if cannot convert into the relevant type.

To cite a Reddit comment:

if your library is the source of a panic, then one of the following should be true:

• Your library has a bug.
• Your library documents a precondition of a public API item that, when not met, causes a panic. Therefore, the user of your library has misused your library, and their code has a bug.

My thought was: Frame rates already become nonsensical after values of 200. A lib user could cap the input, from whereever it's sourced, to, e.g., 100_000 or something lower. A frame rate of 0xffff_ffff would be insane. The high-speed camera record lies at 1_160_000 fps, which is still well below 0xffff_ffff. But high-speed camera videos are always played back at much lower frame rates, and will also be stored in video files with sensible frame rates.

But since an f64 can be invalid in more ways than just being extraordinarily large, I proceeded to return an Option<...>.