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Timezone Bullshit

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Re: Timezone Bullshit

#211

Post by et-al »

DavidPeiffer wrote: post #131
Ayesh wrote: post #102

Earlier quoted context omitted.

Tzdb has the date and time that location starts/reverts DST. It is updated regularly to keep up with regions changing the time zones. It happens frequently than many of us like.

I'm not sure I follow (and this week, timezones and time handling are really important for my job, so I really want to understand)! If a user provides a time of 11/7/2021 1:50 AM America/New_York, how does the library determine if it's a -5 or -4 offset given that's when daylight savings time ends? I believe that's the ambiguity GP is referring to. I'm trying to align time across a few systems I work with. One provid…

> If a user provides a time of 11/7/2021 1:50 AM America/New_York, how does the library determine if it's a -5 or -4 offset given that's when daylight savings time ends?

Edit: I originally misunderstood your question. Since (in the future) 2021-11-07 02:00 is when we change to standard time, how does a library know whether to apply a -5 or -4 offset to 01:50?

The library will need to make assumptions about the inputs and it would probably stick with the original offset (one should check the source). For a human-facing interface, it'd be a good idea to raise the issue.

Re: Timezone Bullshit

#212

Post by klyrs »

macintux wrote: post #46
Lvl999Noob wrote: post #43

Earlier quoted context omitted.

On the topic of DST... can you explain why some countries use DST? Anytime I look for the reasoning of it, it says that DST helps "make better use of daytime" but how? The earth isn't gonna say "Damn! These people changed their clocks. I better change by rotation and give them more sun time." Whether you have DST or not, you still have the same amount of time with sunlight in a day.

Just once I’d like to have a time zone discussion on HN that doesn’t devolve into pages of arguing about daylight saving time. If you search HN you’ll find plenty on this topic.

I mean, you're not wrong... but what else is there to talk about?

Fact of the matter is, your preferences depend on where you live, your lifestyle, and the amount of time you spend on date&time fuckery in code. It's a contentious issue.

Re: Timezone Bullshit

#213

Post by GoblinSlayer »

remram wrote: post #169
GoblinSlayer wrote: post #129

Earlier quoted context omitted.

People in other parts of the world can reach me at any time by email, during the work hours of the email server.

If that is how everyone at your company feel, you don't need a schedule at all (or even a clock).

It's just the best way of contact, if people know anything else, they can use it, but even in one building it's impossible to know who is on vacation, who is fired, who is on lunch, who is on a smoking break, who is off on an errand, who left a little earlier, who is busy at a meeting, who is just busy.

Re: Timezone Bullshit

#216

Post by xyzelement »

Lvl999Noob wrote: post #43
jwalton wrote: post #27

Another reason not to use EST/EDT is that they are overspecifying the time zone in most cases. If you ask for output in EDT, but the date is in December (which is not part of daylight savings time) then should the date output be UTC-4 or UTC-5? Technically you asked for EDT. Using EST as a shortcut isn’t a good idea, either - most software will “know what you mean” and use EST or EDT appropriately... except, both The…

On the topic of DST... can you explain why some countries use DST? Anytime I look for the reasoning of it, it says that DST helps "make better use of daytime" but how? The earth isn't gonna say "Damn! These people changed their clocks. I better change by rotation and give them more sun time." Whether you have DST or not, you still have the same amount of time with sunlight in a day.

You got a bunch of longish replies to your question and I can't tell if they covered the simple answer. DST changes the question of : is it dark at 7am when I get up or not? is it light when I get off work at 5 or not?

It aims to shift the usable daylight hours to correspond with human activity.

Re: Timezone Bullshit

#217

Post by Izkata »

jmgao wrote: post #31
jwalton wrote: post #27

Another reason not to use EST/EDT is that they are overspecifying the time zone in most cases. If you ask for output in EDT, but the date is in December (which is not part of daylight savings time) then should the date output be UTC-4 or UTC-5? Technically you asked for EDT. Using EST as a shortcut isn’t a good idea, either - most software will “know what you mean” and use EST or EDT appropriately... except, both The…

> both The USA and Canada have been toying with the idea of dropping daylight savings time Individual states are toying with the idea as well [1], which presents a problem if one of the tzdata locations decides to change its rules. You're screwed no matter what you choose to do. :-( 1: https://www.syracuse.com/state/2020/11/state-senator-introdu...

It gets worse: DST in Indiana has to be handled on a per-county basis for anything prior to 2006.

https://en.m.wikipedia.org/wiki/Time_in_Indiana

Re: Timezone Bullshit

#218

Post by ghaff »

wiredfool wrote: post #182
throw0101a wrote: post #52

Earlier quoted context omitted.

The closer one is to the poles, the more the number of hours of daylight shifts over the seasons. So at/near the equator, in a place like Panama, you will get roughly 12 hours of daylight in both the December and June Solstices. * https://www.timeanddate.com/sun/panama/panama Whereas in the Edinburgh you go from having 7 hours of daylight in December to over 17 hours in June: * https://www.timeanddate.com/sun/uk/edin…

The worst thing is that the farther north you go, the less it matters. In Ireland, DST only really makes a difference for a month or so around the change. In the summer, light. In the winter, dark.

DST mostly matters between about 35-50 degrees latitude. Less than that and the days are similar enough in length throughout the year that it doesn't really make sense to change clocks. And, as you say, much further north (or south) you have more light than you know what to do with in the summer and you're probably largely in darkness outside of work hours in the winter whatever fiddling you do.

Re: Timezone Bullshit

#219

Post by mindslight »

ghaff wrote: post #178
icoder wrote: post #174

Earlier quoted context omitted.

So then you're back to square one right? Where (apparently) the preference was given to DST (with its downsides), above sub-optimal schedules. (Edit: Combining both your replies I think that may actually be your point)

My preference is definitely to slant towards evening sunlight, so DST year round. (I actually live somewhere that should really be in the next timezone east anyway.) Though I'm at least somewhat sympathetic to people who don't want kids to be waiting for school buses or otherwise heading to school in pitch darkness in the winter.

> I'm at least somewhat sympathetic to people who don't want kids to be waiting for school buses or otherwise heading to school in pitch darkness in the winter.

That's another problem that needs to be fixed on its own, by moving the school schedules back an hour or two and making older grades start later instead of earlier. There has been enough research showing that the current schedule is horrible for learning.

Re: Timezone Bullshit

#220

Post by somehnguy »

xyzelement wrote: post #216
Lvl999Noob wrote: post #43

Earlier quoted context omitted.

On the topic of DST... can you explain why some countries use DST? Anytime I look for the reasoning of it, it says that DST helps "make better use of daytime" but how? The earth isn't gonna say "Damn! These people changed their clocks. I better change by rotation and give them more sun time." Whether you have DST or not, you still have the same amount of time with sunlight in a day.

You got a bunch of longish replies to your question and I can't tell if they covered the simple answer. DST changes the question of : is it dark at 7am when I get up or not? is it light when I get off work at 5 or not? It aims to shift the usable daylight hours to correspond with human activity.

>It aims to shift the usable daylight hours to correspond with human activity.

But it fails miserably at it.. Here in NYS all winter long it gets dark at 5PM. Summer, 9PM.

It's useless and just causes inevitable confusion every year.

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