[Telepathy] Geolocation in Telepathy

[Mikhail Zabaluev]

Hi,

2008/3/3, Jussi Kukkonen <jhkukkon at cc.hut.fi>:
>
>
> The C function looks like this:
>
>     GeocluePositionFields
>     geoclue_position_get_position (GeocluePosition  *position,
>                                    int              *timestamp,
>                                    double           *latitude,
>                                    double           *longitude,
>                                    double           *altitude,
>                                    GeoclueAccuracy **accuracy,
>                                    GError          **error);
>
> where the return value is a validity bitfield. So a check for altitude
> validity would be "if (retval & GEOCLUE_POSITION_FIELDS_ALTITUDE)".


As you allocate output structures and fill the call stack with pointers
anyway, I'd prefer that with a handier signature:

GeocluePositionData *
geoclue_position_retrieve (GeocluePosition *position, GError **error);

Then a validity check would be:

if ((data->field_flags & GEOCLUE_POSITION_FIELDS_ALTITUDE) != 0) {
    /* use data->altitude */
}

For convenience, the field validity checks could be macroized around a
pointer to GeocluePositionData.

BTW, position data could even be DBus properties on GeocluePosition. In
Telepathy, we're considering DBus properties where a Telepathy-specific
property access interface, or other assorted methods, are currently used.
Simon knows better if it's a worthwhile approach or not.

> Then, if we consider Python bindings, a straightforward binding would
> > turn the above into:
> > (time, lat, lon, alt, accuracy) = pos.get_position()
> >
> > Not very convenient if you need only some of those values.
>
>
> Not much of a python developer myself, so I can't judge how inconvenient
> that is...Would you say it's difficult for the binding to wrap that in a
> way that would be more natural to a python developer?


No, I'd create an object with data access fields or methods anyway. I just
can't see why the C API should be much different then.

Best regards,
  Mikhail
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