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It’s not just time zones and leap seconds. SI seconds on Earth are slower because of relativity, so there are time standards for space stuff (TCB, TGC) that use faster SI seconds than UTC/Unix time. T2 - T1 = [God doesn’t know and the Devil isn’t telling.]
I just spent two days debugging a reporting endpoint that takes in two MM-YYYY parameters and tries to pull info between the first day of the month for param1 and the last day of the month for param2 and ended up having to set my date boundaries as
LocalDate startDate = new LocalDate(1, param1.getMonth(), param2.getYear()); //pretty straightforward, right?
//bump month by one, account for rollover, set endDate to the first of that month, then subtract one day
int endMonth = param2.month == 12 ? param2.month + 1 : 1;
LocalDate endDate = new LocalDate(1, endMonth, param2.year).minusDays(1);
This is extraordinarily simply for humans to understand intuitively, but to code it requires accounting for a bunch of backward edge/corner case garbage. The answer, of course, is to train humans to think in Unix epoch time.
In the example you gave, wouldn’t the year be off by one when param2.month is 12?
I was transcribing it from memory and that exact problem cost me like two hours when I was writing it the first time. Well spotted, now write me a unit test for that case.
Using YearMonth.atEndOfMonth would have been the easier choice there, I think
holy shit, yeah it would have. tyvm, I’ll be putting in a PR first thing monday!
Would you mind trying to explain (ELI5 style) what you did before and why you are excited for this new method for those of us who dont understand code?
Unix epoch time in UTC, making sure that your local offset and drift are current at the time of conversion to UTC…
All dates and times shall be stored and manipulated in Unix time. Only convert to a readable format at the top of the UI, and forget trying to parse user inputs :P that’s just impossible
C++ user with operator overloading: “T2 minus T1.”
Let someone else implement the class. There’s probably a library for it.
LOL whenever I have to work with DateTime systems that try to account for every possibility (and fail trying) I am reminded that in some disciplines, it’s acceptable to simplify drastically in order to do ‘close enough’ work.
I mean, if spherical cows are a thing because that makes the math of theoretical physics doable, why not relativity-free or just frame-constant date-time measures that are willing to ignore exotic edge cases like non-spherical livestock?
Because “relativity” isn’t even close to your biggest problem with time. The way we communicate time changes historically, unpredictably, without obvious record. The only way to know what time you’re talking about is to know exactly how you got your information. What location, measured at what time relative to recorded changes in the local time zone, with how much drift relative to the last time you synchronized to which ntp server, and so on. These things easily account for hours or days of error, not just nanoseconds.
Ah I’ve gotten to the point where I have to define what “frame” and epoch each time base is in before I’ll touch the representation of time( Unix,Gregorian, etc) .To be honest I’m probably just scratching the surface of time problem.
Hell probably the reason we haven’t seen time travellers is we suck at tracking time and you probably need to accurately know your time and place to a very good precision to travel to a given point and we can’t say where and when that is with enough accuracy to facilitate where to land. And people don’t want to land in the earth’s surface or 10000 km away from a stable orbit. Maybe some writer can build that out for a time travel book or to discount it for some reason lol
Then there’s continental drift, which as Indiana Jones reminded us this past summer, Archimedes didn’t know about when he built his time machine.
Pet peeve: brushing aside the time travel fantasy element, there is not a single shred of evidence of any type of connection between Archimedes and the Antikythera Mechanism.
As if the only person clever enough in Ancient Greece was that one famous dude from Syracuse.
Ionians: “Are we a joke to you?”
I recall a short story like that where someone died because they time traveled, but didn’t account for position.
Highly recommended
SPOILER
I want little Emily to change her future. A sequel is needed!
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(Thanks for sharing, was a good watch.)
