Provide access to subsecond nanos in the public interface of Duration.

[tylerreisinger]

The way the Duration struct is implemented, if there are more total nanoseconds represented than i64::MAX, it is impossible to see greater than millisecond precision on the outside despite that information being stored. It would be useful to have a method similar to std::time::Duration::subsec_nanos which can return only the number of nanoseconds past the nearest second.

Additionally, for interfacing with chrono, it would be useful to have a constructor to create a Duration from a number of whole seconds plus the additional nanoseconds similar to std::time::Duration::new to efficiently construct Duration objects with full precision.

[lifthrasiir]

I don't intend to modify time::Duration by now, but I plan for the new duration-like type for Chrono 0.4.1 (originally intended for 0.4.0 but delayed due to the time constraint) and I'll take care of this suggestion. Thank you for pointing out.

[kosta]

@lifthrasiir is there a public branch that I can track for the time::Duration replacement?

[kangalio]

What is the state of this? I am working on implementing chrono support for the PyO3 Python bindings crate. Chrono's lacking Duration API artificially limits the size of Duration's that can be supported, which is unfortunate.

[pickfire]

@kangalioo I think adding it as a feature to chrono does not requires us to change the public interface. #542

[pitdicker]

Added in #1327.

[kangalio]

Thanks!

I would vouch to re-open this issue though, because the second part of the issue is not part of #1327:

Additionally, for interfacing with chrono, it would be useful to have a constructor to create a Duration from a number of whole seconds plus the additional nanoseconds similar to std::time::Duration::new to efficiently construct Duration objects with full precision.

This specifically is what would be needed in pyo3 to support sub-second precision in the Python<->Rust conversion (code permalink)

[djc]

Please just file a new issue so we can track that request separately.

[pitdicker]

Sorry, I missed that part of the first post. #1137 includes a Duration::new method.