I have anxiety now...
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It's a YT video. It's supposed to make things dramatic and conflicted. Any real professional programmer should know how to deal with timezones this day and age. There's no excuse, unless you're an intern or something like that.
Jeremy Falcon
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Yet I have seen a developer I would clarify as highly competent do "DateTime.Now.ToUniversalTime()". I have seen code break because it did not handle DateTimeKind.Unknown and some upstream code changed. Yes, it is quite simple, yet mistakes happens.
lmoelleb wrote:
Yet I have seen a developer I would clarify as highly competent do "DateTime.Now.ToUniversalTime()".
That in and of itself isn't bad. It would be context dependent as to whether that's bad or not.
lmoelleb wrote:
Yes, it is quite simple, yet mistakes happens.
For sure, but it's not as bad as some would suggest. I'd argue dealing with OS API compatibility or browser compatibly issues are far more involved (well not as much as it used to be).
Jeremy Falcon
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I use DateTimeOffset instead of storing in UTC. Too many things can go wrong in the conversion when using DateTime. I have seen highly experienced developers doing stupid things like DateTime.Now.ToUniversalTime()
lmoelleb wrote:
I use DateTimeOffset instead of storing in UTC.
I don't do .NET these days, but would that not use the same conversions internally to figure out the offset? So, what's the advantage over just converting to UTC and sticking with it?
Jeremy Falcon
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You said it was not a great idea? I agree it is hard to clasify as "great", just an extremely simple way to minimize a problem.
Storing local times for any application is a bad idea. I'm sure Richard is just speaking from experience.
Jeremy Falcon
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I use DateTimeOffset instead of storing in UTC. Too many things can go wrong in the conversion when using DateTime. I have seen highly experienced developers doing stupid things like DateTime.Now.ToUniversalTime()
I was using
DateTimein a generic way, meaning an object that expresses a point in time, whether a Database object, program variable or datum in a flat file. I did not intend to refer to any specific version of a Date/Time object."A little song, a little dance, a little seltzer down your pants" Chuckles the clown
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Totally agree. Well, except I believe that everything should be stored in UTC. Just get used to it already. But, especially before the Internet and globalization, anti-timezone peeps act like not having a timezone would be better. But, just imagine the chaos of morning sunrise happening at 11:00PM. It's just trading one confusion for another. People want to act smart by looking behind them (easy to do) and insulting things. But, I can promise, given the state of the world, most everyone would be agreeing to use them if they were alive and well during that time. IMO daylight savings time did more harm than timezones. Again, I can see why it was created. But, it caused more issues than timezones. Timezones were never really an issue.
Jeremy Falcon
Jeremy Falcon wrote:
everything should be stored in UTC
I've been using Unix Epoch (seconds since Jan 1, 1970 UTC+0) i.e. a
time_tto store most times since the late 80's. Which is the same idea. It represents a fixed moment in time, and what semantic interpretation is up to any locale information that's active at any given moment."A little song, a little dance, a little seltzer down your pants" Chuckles the clown
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Even outside time zones it's all hard enough. We are now contending with the slowing of the earth spinning causing days to be ms longer. We'll soon start to contend with time in space, not to be confused with space-time.
jochance wrote:
We'll soon start to contend with time in space, not to be confused with space-time.
[A moon time zone? Why NASA is racing to set one.](https://www.usatoday.com/story/graphics/2024/04/23/why-moon-time-zone-is-needed/73288518007/#:~:text=On Earth%2C Coordinated Universal Time,one or multiple time zones.)
"A little song, a little dance, a little seltzer down your pants" Chuckles the clown
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You said it was not a great idea? I agree it is hard to clasify as "great", just an extremely simple way to minimize a problem.
No, what I actually said was
Quote:
Not using UTC because some developers do stupid things, is hardly a great idea.
.My point being that to do, or not do, something because some other developer may make a mistake, or do something stupid, is not really good decision making. It was not meant to be specific to DateTime or DateTimeOffset.
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Storing local times for any application is a bad idea. I'm sure Richard is just speaking from experience.
Jeremy Falcon
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No, what I actually said was
Quote:
Not using UTC because some developers do stupid things, is hardly a great idea.
.My point being that to do, or not do, something because some other developer may make a mistake, or do something stupid, is not really good decision making. It was not meant to be specific to DateTime or DateTimeOffset.
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lmoelleb wrote:
I use DateTimeOffset instead of storing in UTC.
I don't do .NET these days, but would that not use the same conversions internally to figure out the offset? So, what's the advantage over just converting to UTC and sticking with it?
Jeremy Falcon
The main advantage is that it natively protect against mistakes. It does not use the same logic internally as DateTime - it stores the offset instead of DateTimeKind. You never have to deal with DateTimeKind.Unknown (primary reason for mistakes I have seen). You never have some database layer having to be told if it is local time or utc. If some idiot use local time... Then nothing happens because it still accurately represents a unique point in time - no matter where in the world that local time was used.
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lmoelleb wrote:
Yet I have seen a developer I would clarify as highly competent do "DateTime.Now.ToUniversalTime()".
That in and of itself isn't bad. It would be context dependent as to whether that's bad or not.
lmoelleb wrote:
Yes, it is quite simple, yet mistakes happens.
For sure, but it's not as bad as some would suggest. I'd argue dealing with OS API compatibility or browser compatibly issues are far more involved (well not as much as it used to be).
Jeremy Falcon
A local time in c# does not represent a unique point in time as it can't store A and B times when transitioning from daylight saving time to standard time. So once you go from local to universal... Good luck. But sure, maybe they chose an implementation that happens to always work in that specific case... But just realizing this is not clear is enough for me to stay clear of that problem.
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The Problem with Time & Timezones - Computerphile - YouTube[^] And yeah, been there done that (luckily not all the exceptions discussed in this video...) :sigh:
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[Noda Time | Date and time API for .NET](https://nodatime.org/)
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The Problem with Time & Timezones - Computerphile - YouTube[^] And yeah, been there done that (luckily not all the exceptions discussed in this video...) :sigh:
Best, Sander Azure DevOps Succinctly (free eBook) Azure Serverless Succinctly (free eBook) Migrating Apps to the Cloud with Azure arrgh.js - Bringing LINQ to JavaScript
Be thankful Special and General Relativistic effects are not considered. "I once put instant coffee into the microwave and went back in time." - Steven Wright
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Totally agree. Well, except I believe that everything should be stored in UTC. Just get used to it already. But, especially before the Internet and globalization, anti-timezone peeps act like not having a timezone would be better. But, just imagine the chaos of morning sunrise happening at 11:00PM. It's just trading one confusion for another. People want to act smart by looking behind them (easy to do) and insulting things. But, I can promise, given the state of the world, most everyone would be agreeing to use them if they were alive and well during that time. IMO daylight savings time did more harm than timezones. Again, I can see why it was created. But, it caused more issues than timezones. Timezones were never really an issue.
Jeremy Falcon
Jeremy Falcon wrote:
Well, except I believe that everything should be stored in UTC.
I did this and then calculated back to the current time zone. So then the customer called and said someone did something in the middle of the night, which was unthinkable. After looking it up I said that person was in another time zone (on vacation) and did something that was middle of the night for him. It was decided that everything should always be stored and shown in their HQ time zone, even when on vacation or when the apocalypse hits. Loved the simplicity, stored current time and never looked back :D
Best, Sander Azure DevOps Succinctly (free eBook) Azure Serverless Succinctly (free eBook) Migrating Apps to the Cloud with Azure arrgh.js - Bringing LINQ to JavaScript
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Why would it be a bad idea to store DateTimeOffset? The way to store date/time I have the most experience with is DateTime stored as UTC. But I see no reason to go back to that - what is the benefit?
My understanding of DateTimeOffset is that it's still a local time, but with offset information. Soooooo, if I'm correct with that... The reason why it's bad is you're adding complexity for no real gain. That date time is still only relevant to you. If you have an application that is used all over the world, then you now must do two calculations to show a time to a user rather than one.
Jeremy Falcon
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The main advantage is that it natively protect against mistakes. It does not use the same logic internally as DateTime - it stores the offset instead of DateTimeKind. You never have to deal with DateTimeKind.Unknown (primary reason for mistakes I have seen). You never have some database layer having to be told if it is local time or utc. If some idiot use local time... Then nothing happens because it still accurately represents a unique point in time - no matter where in the world that local time was used.
Well, I don't know enough about the C# structures to speak intelligently on the matter. So, there's an 82.5% chance I'm talking out of my arse. :laugh: But, generally speaking, it's bad to store anything in local time. And trying to make code idiot proof is impossible, especially at the expense of making the code harder to follow. That's what code reviews are for. You're adding more complication to the product just because of a DateTimeKind.Unknown situation when it's so much easier to just keep everything in UTC.
Jeremy Falcon
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A local time in c# does not represent a unique point in time as it can't store A and B times when transitioning from daylight saving time to standard time. So once you go from local to universal... Good luck. But sure, maybe they chose an implementation that happens to always work in that specific case... But just realizing this is not clear is enough for me to stay clear of that problem.
Wouldn't that make UTC more appealing then? Then you only have to do one conversion when going back to local.
Jeremy Falcon
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Jeremy Falcon wrote:
Well, except I believe that everything should be stored in UTC.
I did this and then calculated back to the current time zone. So then the customer called and said someone did something in the middle of the night, which was unthinkable. After looking it up I said that person was in another time zone (on vacation) and did something that was middle of the night for him. It was decided that everything should always be stored and shown in their HQ time zone, even when on vacation or when the apocalypse hits. Loved the simplicity, stored current time and never looked back :D
Best, Sander Azure DevOps Succinctly (free eBook) Azure Serverless Succinctly (free eBook) Migrating Apps to the Cloud with Azure arrgh.js - Bringing LINQ to JavaScript
So then display the time info in the appropriate time. There's no rule saying you can't do that. UTC is just internal to the app. Good luck doing datetime math in local time all over the world. It'll be a living nightmare.
Jeremy Falcon
