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Re: Spec update: deviceorientation event should fire when listener is first registered

From: Bjoern Hoehrmann <derhoermi@gmx.net>
Date: Tue, 12 Jul 2011 22:00:13 +0200
To: Andrei Popescu <andreip@google.com>
Cc: public-geolocation <public-geolocation@w3.org>
Message-ID: <k75p175h3gilggbqiccacoav6v100chhct@hive.bjoern.hoehrmann.de>
* Andrei Popescu wrote:
>If all you need to know is whether the device is still or not,
>wouldn't it be easier to use the DeviceMotion Event? I think that
>would get around the need to special-case the first event in your
>usecase.

I think it is important to understand that authors don't always make the
best choices and they are unlikely to anticipate that listeners for sig-
nificant changes are invoked even when there have been no changes, just
as they are unlikely to expect that listener registration triggers other
listeners. Violating expectations usually leads to problems, so I wanted
to be clear that there may very well be negative implications here. The
example was only meant to illustrate how this may lead to problems.

My impression is that if you need workarounds like this, then the event
system may not be the best interface to expose this information, so the
concerns in this thread should not be dismissed as easily as just saying
it's good because it's not that bad. The draft doesn't do a good job ex-
plaining all the constraints at work (can you always learn the current
orientation and quickly enough so a synchronous interface to that would
be possible, or is it slow to turn on the necessary sub-systems and it
may be necessary to calibrate -- would be one question); so it's hard to
find alternatives how to use the event system better, or other designs
that might be more suitable to convey the information.
-- 
Björn Höhrmann · mailto:bjoern@hoehrmann.de · http://bjoern.hoehrmann.de
Am Badedeich 7 · Telefon: +49(0)160/4415681 · http://www.bjoernsworld.de
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Received on Tuesday, 12 July 2011 20:00:28 UTC

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