Hi,

I am wondering how best to calculate velocity in a moby/phonegap/android 
application.
In general, would anyone have experience (or intuition) whether velocity might 
better be calculated from the acceleration values delivered by phonegap's 
Acceleration object, or directly be extracted from the Position object returned 
from Geolocation (it has a field 'velocity')?

Otherwise I'd plan to test and compare both ways, and for that, I'd have a 
technical question (most probably to Danny :-) ):
At the moment, the successCallback in the adapted phonegap.js receives the 
latitude and longitude only, whereas in the original (current) phonegap.js the 
complete Position object is returned. Is this intentional - I mean, does moby 
diverge from phonegap on purpose here (like experience showed the other fields 
are not reliable anyway, or not too much requested by users, or ...)? Or was 
this a modification to keep it simple at first, to be possibly extended later?
Also, what would be the way to adapt the racket side of it -  given 
on-location-change's contract,


(on-location-change world-updater) → handler
  world-updater : (world [latitude number] [longitude number] -> world)


would you make world-updater a variable arity function, or use case-lambda or 
keyword arguments to obtain the desired flexibility, or rather create and pass 
a 'position' object analogous to the javascript-side Position object?

BTW I noticed that in phonegap's (current) phonegap.js, there are no observers 
for orientation and shake... I'm just curious, was this functionality added 
during moby implementation (i.e., it never existed in phonegap's own 
phonegap.js), or it was removed in a newer phonegap release?

Many thanks in advance,
Sigrid 







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