111–120 of 333 posts
I used to work at a company that stored all dates as ints in a YYYYMMDD format. When I asked why, I was told it was so we could subtract 2 dates to get the difference. I asked them why they couldn’t use DATEDIFF since this was in a sql db. They said they hadn’t heard of it and that it must be new.
In mainframes, Julian dates are popular for that reason. YYDDD (day of year). When is 30 days after today? 25206+30
No other programming concept has caused me more grief than dealing with time and timezones. It starts to get really mind-bendingly complex once you start thinking about it deeply. That is even before you start encountering the quirks (some places have timezone changes that depend not only on the time of year but also on the actual year). Lesson learnt - choose a library (moment is great) and never think about time ag…
You just need to understand how time works if you write code handling time.
When ever i see "never implement your own...", i know i want to implement it myself. People say that about hard things, and I only want to do hard things. Nobody wants people who can do easy things, people want people who can do hard things. The only way to learn how to do hard things, is to do hard things, so do the hardest things. So go ahead, write your own date library, your own Unicode font rendering, compiler,…
[0] https://www.space.com/astronomy/earth/earth-will-spin-faster...
Earlier quoted context omitted.
By all means, write it. Just don't use it. These warnings are almost always in the context of code you're going to release, not exercises in learning on your own.
This is such nonsense. All the stuff that we use, someone wrote. If nobody makes them, then how is that going to work? The messaging here is that you should be careful about using what you build on your own because it: - hasn't been battle tested - likely has bugs - isn't mature The only way that it will be all of those things is if someone invests time and energy in them. From an ecosystem perspective this is absolu…
I see it as “Dont write your own X, unless you want to maintain X. Here be dragons, this problem is deeper than it appears, the first 80% will be easy, the next 15% will annoy you, and the last 5% will consume your life for weeks, months, or even years. Or you could use a library”
I wrote my own, so had to click, but mine was for a very different use case: converting extremely varied date strings into date ranges,
where a significant % of cases are large number are human-entered human-readable date and date range specifiers, as used in periodicals and other material dating back a century or two.
I.e. I had correctly interpret not just ISO dates, but, ambiguous dates and date ranges as accepted in (library catalog) MARC records, which allows uncertain dates such as "[19--]" and "19??", and, natural language descriptors such such as "Winter/Spring 1917" and "Third Quarter '43" and "Easter 2001." In as many languages as possible for the corpus being digitized.
Output was a date range, where precision was converted into range. I'd like to someday enhance things to formalize the distinction between ambiguity and precision, but, that's a someday.
When schema is totally uncontrolled, many cases are ambiguous without other context (e.g. XX-ZZ-YYYY could be month-day-year or day-month-year for a large overlap); and some require fun heuristics (looking up Easter in a given year... but did they mean orthodox or...) and arbitrary standards (when do seasons start? what if a publication is from the southern hemisphere?) and policies for illegal dates (Feburary 29 on non-leap-years being a surprisingly common value)...
In a dull moment I should clean up the project (in Python) and package it for general use...
Earlier quoted context omitted.
By all means, write it. Just don't use it. These warnings are almost always in the context of code you're going to release, not exercises in learning on your own.
This is such nonsense. All the stuff that we use, someone wrote. If nobody makes them, then how is that going to work? The messaging here is that you should be careful about using what you build on your own because it: - hasn't been battle tested - likely has bugs - isn't mature The only way that it will be all of those things is if someone invests time and energy in them. From an ecosystem perspective this is absolu…
The point is, before you release your new thing, make sure it addresses all of the pain points the previous solutions have already slogged through,
or that if it doesn't, people are still aware of when they can arise, and why your thing has chosen not to mitigate them yet,
or ever, if it's an opinionated piece of tech.
I ran into date heck recently in a medical setting for storing birthdates. Eventually I settled on the idea that a birthdate isn’t a physical time, it’s just a string. We can force the user to enter it in the format 02/18/1993 leading zeroes and all, and operations on it other than string equality are invalid. We’ll see if this survives contact with the enemy but it’s already going better than storing and reasoning a…
FHIR in my opinion has a pretty good system for dates (including birthdates): YYYY, YYYY-MM, or YYYY-MM-DD. (Not knowing your exact birthday is common for some countries).
Earlier quoted context omitted.
By all means, write it. Just don't use it. These warnings are almost always in the context of code you're going to release, not exercises in learning on your own.
This is such nonsense. All the stuff that we use, someone wrote. If nobody makes them, then how is that going to work? The messaging here is that you should be careful about using what you build on your own because it: - hasn't been battle tested - likely has bugs - isn't mature The only way that it will be all of those things is if someone invests time and energy in them. From an ecosystem perspective this is absolu…
The things that people write that everyone uses have had HUGE exposure.
They've been exposed to all the edge cases, they've been tested millions, if not billions of times. All the bugs ironed out.
The people who've worked on them are now the greatest domain experts on that little corner of comp-sci.
Yours won't unless it hits prime time.
So yours will be weak, brittle and dangerous.
In UIs prefer date/time pickers instead of raw text inputs which will give the date/time in standard ISO format such as ("2025-07-25" or "2025-07-25T18:47:26.022Z"). Prefer ISO formats everywhere where possible.
While I am fairly sure this a a locale defined thing. locales are this huge pile of worms and I have never figured out how to change it to show YYYY-MM-DD format
When ever i see "never implement your own...", i know i want to implement it myself. People say that about hard things, and I only want to do hard things. Nobody wants people who can do easy things, people want people who can do hard things. The only way to learn how to do hard things, is to do hard things, so do the hardest things. So go ahead, write your own date library, your own Unicode font rendering, compiler,…
I agree with you though, do the hard things even if it doesn't work 100% right you will have learned a lot. In university I had to implement all of the standard template library data structures and their features, it wasn't as robust as the actual STL but the knowledge of how those work under the covers still comes up in my day to day job.