How to get “today” or “now” in ICU

[Lucretiel]

Is there a straightforward way to get "today's date" or "now" using icu_calendar? There don't seem to be any conversions from Instant, nor any functions in that crate resembling now or today, nor any constructors that don't have you bring all of your own datetime components. Is there something I'm missing? It seems like a shame to being another heavyweight timestamps crate, like time or chrono, just to do this initializer step for icu.

[sffc]

I agree that it would be useful to provide a well-lit path for formatting the current time in ICU4X. However, I'm not sure if doing it all internally in ICU4X is the right architecture. Some challenges:

1. The primary value proposition of ICU4X's primitives in icu_calendar is for converting between calendar systems and formatting localized output, something out of scope for chrono and time. It would be scope creep to include code for processing system times and time zones in ICU4X, which is a nontrivial amount of code to write and perpetually maintain.
2. std::time exposes a mechanism to get the current UTC timestamp, but it says nothing about time zone or local time, which means it is not enough on its own for extracting a DateTime. Some other crate is necessary in order to get information on the local time zone.

What is in scope for ICU4X is the handling of time zone transitions and performing time zone calculations, since this is required by both ECMA-402 and Temporal and can be done as no-std. Therefore, I do expect ICU4X will get a function where the user provides the current timestamp and time zone and can get a DateTime. There could also be a convenience function gated on the std feature where the user provides only the time zone and ICU4X uses std::time to get the timestamp.

[savannidgerinel]

I think that's very reasonable. I'd be very happy with a function akin to as DateTime::new_from_timestamp(std::time::SystemTime, [something timezone-ish]), or DateTime::new_from_chrono(chrono::DateTime<FixedOffset>).