Can you elaborate on what you are looking for here? Indigo has the API but no type of trigger or change callback hook for it. You can, of course, cache off the value and periodically call the API to see if it has changed.
Of course I can poll periodically, but polling sucks.
The easy way would be a Plugin method that gets called whenever there's a change to what
server.getLatitudeAndLongitude() would return. Call that when the preference is changed, or when the system location changes. (You
are getting notifications about this, right? Or at least checking when the system wakes up?)
If the location were a state or property or variable, then us interested developers could just register for change notifications and you'd be all set. (Of course, here we run into the fascinating limitations of the current implementation as to the supported types of these various things. The location is a tuple.)
I can work around this particular issue by re-checking upon wake-up, and by just sternly telling my users to restart my plugin whenever they change the Indigo preference. But I'd like you to give some thought to unifying instance attributes, utility function results, plugin properties, device properties, and device states into something that can be observed in a uniform way. 'cause that's easier on all of us... and 'cause Python can totally do this (with descriptors).
Cheers
-- perry