Why do some functions panic instead of returning a Result<T, E>?

[BlueSialia]

Right now I'm parsing some information I receive in UDP messages. Some of that information is timestamped but if something goes wrong on the sender I can receive random bytes so if I try to parse those bytes as dates I get a panic with 'No such local time'.

And I wonder. If the function Local.ymd(y, month, d).and_hms(h, min, s) can fail why not return a Result instead?

[dzfranklin]

I think those functions are intended for building timestamps from known good values. You might be looking for DateTime::parse_from_str which lets you specify the format you're trying to parse in the standard unix-y way and returns a result. Don't take me too seriously, I'm a random person who saw this while filing their own question.

[BlueSialia]

I see where you are coming from. But I do not have a String, though. I could create it to then parse it, but that feels like an ugly hack.

Regardless, I was under the assumption that Rust code practices were about working with Result and Option whenever some function could fail. That Rust is reliable because runtime errors should only happen if the programmer uses unwrap() (an similar functions) or unsafe code.

[deviant]

The time crate (which this depends on) placed panicking functions behind a feature gate and switched to providing try_ functions instead. This should too.

[c-git]

Is there something I can do to move this forward? I prefer not need to check each function to see if it might panic. Maybe offer parallel functions that do not panic so it's not a breaking change?

[djc]

Feel free to submit PRs to create non-panicking alternative APIs en add deprecations for the panicking calls.

[c-git]

Ok thank you, I will try to do it. Just to get a feel for naming preference, should I just add try_ to the front of the functions I change?

[djc]

That seems like a reasonable first approximation. Our constructors mostly have _opt() suffixes at this point, let's see what works in context.

[c-git]

Got it, will try to see if I can find a pattern. The name can always be refactored, I don't get attached to them

[c-git]

Haven't forgotten about this but my schedule has been kind of full so if someone else gets to it first that's fine otherwise I will give it a go once I can put some time aside.

[pitdicker]

Closing in favor of #1049. We have non-panicking alternatives to almost all methods now, and making them default for 0.5 is definitely on the roadmap.