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From: "Martin Dowie" <martin.dowie@btopenworld.com>
Newsgroups: comp.lang.ada
Subject: Re: Inserting Calendar.Time in a database
Date: Sun, 8 Aug 2004 08:35:07 +0000 (UTC)
Organization: BT Openworld
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Date: 2004-08-08T08:35:07+00:00
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"Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de> wrote in message
news:13x45njobjvn3.yhisk87dws3.dlg@40tude.net...
> On Sat, 7 Aug 2004 09:50:18 +0000 (UTC), Martin Dowie wrote:
>
> > Or just read the UTC Offset until you get 2 values that are the same...
>
> (:-)) Consider an Ada system put in a car moving along a time zone
> margin...
>
> But seriously, there are requirements on time stamps Ada.Calendar.Time
does
> not meet:
>
> 1. Not monotonic

It can be monotonic. I'd be a little surprised if it wasn't on
implementations that also provided Ada.Real_Time but I'm sure someone will
now point to examples where this isn't true ;-)


> 2. Coarse granularity (12 ms in the worst case)

Yup, that's coarse but then for most implementations Ada.Calendar and
Ada.Real_Time are just going to give you what the underlying OS/hardware
provide.


> 3. Two clock readings are not unique

???

> And why a small networking embedded system (intelligent sensor, for
> example), which needs synchronized clock should use Ada.Calendar, maintain
> time zone data base etc?

I'm sure we could come up with lots of 'little' examples about where this
isn't the 'best' solution. But the standard libraries (to me) are there to
make the common things easy to do. For 99% (99+%?) these packages will be
fine.

Cheers

-- Martin