On 04/01/11 20:52, Milan Bouchet-Valat wrote:
> Le mardi 04 janvier 2011 à 15:51 +0000, gpk a écrit :
>> Actually, on consideration, I don't think that automatic detection of
>> the timezone is a viable solution. It suffers from all kinds of potential
>> problems
>> like "What does it do if it's connected to a VPN?". If I connect via VPN
>> to my office in the UK when I'm in France, I'd get the incorrect time.
> People using VPNs are not the majority, and we can disable automated detection
> of timezone if we're connected over a VPN. Plus, we can also use GPS devices
> when present.
OK. Kind of OK, anyway. But that means a traveller has to know
and remember the rule
about VPNs. If they don't, they will swear at you. You will get
people saying "I know I
connected to the network, why didn't the damn thing set the clock properly?"
And, doubtless, developers will respond "RTFM". But RTFM is a
hopeless task these days!
My Ubuntu system has tens of thousands of pages of documentation. You
have to design a
system that will not mislead people in important ways, even if they have
had better things
to do than read the Gnome documentation.
>> Or, if I'm in the airport and I'm not yet connected to a network in my
>> new location, it will be silently giving me incorrect timezone information.
>> ... That's acceptable if you know you have to
>> set it manually, but people will depend on an automatic system, and miss
>> their connecting flights.
> If people are smart enough to change their timezone manually, they are smart
> enough to understand their laptop still uses the previous timezone
> because it has no way of finding out you've moved.
>
Wrong. It's a very different process in the two cases.
Manual case: you just have to remember "did I set it or not"? *You*
are the only actor.
Automatic-but-imperfect case: You have to understand how the automatic
time-zone setting logic works.
1) You have to know that it gets its time from looking up its IP address
in a table.
2) You have to keep track of whether the computer has connected to a
network.
2a) It may connect without your knowledge -- if you go somewhere you
have been before, it
may detect up a WiFi network where it has the password and
autoconnect.
2b) It may fail to connect somewhere you expect a connection.
Hardware could be down,
or overloaded, or the signal could be too weak, or a password
expired...
3) Even if it does connect, do you know that it has a global IP address
in the right country?
3a) There's the VPN problem.
3b) There's the possibility that you have a IP address behind a
firewall. You may be getting
data, but it might not be able to deduce where it is.
3c) You may be getting your IP address from a cellullar base
station on the other side of the border.
4) The software is depending on a map from IP addresses to geographical
location.
4a) How accurate is that map?
4b) How rapidly is it updated if some big ISP moves a block of IP
addresses from one time zone
to another?
In principle, you need to run through that entire checklist each time
you've looked at the clock.
That's a different, and harder task from just remembering to set the clock.
Or, to be sure, you can open up the timzeone widget and check to see if
the computer's idea of the
time zone agrees with reality. But, if you're going to do *that*, you
might as well just set it.
Another argument is that from a human social point of view, blaming your
computer for having
the wrong timezone just doesn't work when you miss an appointment.
Whoever you
try to apologize to will just be thinking "What an idiot! Everyone else
can keep track of
what time zone they're in."
Anyhow, it's one of these things that isn't a good idea to automate,
unless you can do it
really well.
> So you'd suggest computers should always wait for users to do things manually,
> just to avoid being smarter than them? The automated solution is better
> than nothing. Anyway, discussing this here is pointless since it will be
> implemented in GNOME and I'm not involved at all in this work.
>
No. I suggest that UNTIL THE AUTOMATED SYSTEM IS 99.999% CORRECT, it
is better to do it manually. The automated solution can be far worse
than nothing.
Just imagine! You fly into Paris for a job interview. You glance at
your laptop
and decide you have time for a espresso. You don't even think about
network
connectivity and clocks. You arrive an hour late for the interview
because the
darn time zone is wrong.
Are you going to be happy?
Essentially, the trade-off is a minor convenience 99.999% of the time,
versus a
modest (or major) disaster 0.001% of the time.
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https://bugs.launchpad.net/bugs/696115
Title:
Timezone should not require superuser on laptop
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