Re: [gpsd-dev] Adding new fields to JSON reports

[Gary E. Miller]

Yo Eric!

On Wed, 1 Apr 2015 15:57:37 -0400
"Eric S. Raymond" <address@hidden> wrote:

> Gary E. Miller <address@hidden>:
> > I have added the "precision" field to the gpsd PPS JSON output.  It
> > is in this afternoon's git head of gpsd.
> 
> Maybe this needed to be done, but you left the job very incomplete.
> As a result, gpsmon is almost certain to have flaky failures.

WIP.  You just beat me to it, 5 mins not a long time for me to upload
the next patch...

> 4. Update the JSON parse templates in libgps_json.c.  If you don't do
> this, clients (including gpsmon) will throw an error when they trip
> over the new field.

That seems less than ideal.  Clients should be able to handle upwardly
compatible changes with at most a warning.  If you can force this to 
happen with precision I'll fix it.

> 5. The hard part: the data wants to go somewhere on the client side,
> but doing this may involve a compatibility break in the user-visible
> core structures.  You need to make a call on whether to extend them
> or accept that the new data will be invisible untol the next
> structure upgrade and if so document that as an item in TODO.

Which also make me questions the core structures.  Maybe better to
convert to a hash style so field can be added with less downside?

RGDS
GARY
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