Re: Change from 3.23 to 3.24 - program doesn't work?

[Mike Tubby]

On 22/06/2022 20:35, Gary E. Miller wrote:
> Yo Mike!
>
> On Wed, 22 Jun 2022 15:57:00 +0100
> Mike Tubby <mike@tubby.org> wrote:
>
> > On 21/06/2022 19:11, Gary E. Miller wrote:
> > > Yo Mike!
> > >
> > > Care to share with everyone?
> > Its a work project, so I would have to remove some code to protect
> > the innocent.
> You get paid, we work for free?  Does not seem fair.  Try to give back
> in some way on the future.

I'll sanitise and post later ...


> >       22-06-2022 13:48:22 GMT [Info] *GPSD version: 3.22 API version:
> > 3.14  App built against API version: 11.0*
> >       22-06-2022 13:48:22 GMT [Notice] GPSD API mis-match ... exiting!
> >
> > the code that generates this error is in my reader:
> That is NOT an error, read what it says.  You have an API mismatch, and
> you either need to change your code for the new API, or stick with the
> old gpsd.


I think we're at slightly crossed purposes.

I am using a matching gpsd version 3.22 and libgps from Debian (actually 
Devuan 4.0) and it works as long as I don't attempt to check.

If I try to check then the things I have to play with appear to be:

    1) the version_t structure; and
    2) the pair of #defines for API major and minor versions

What's in the version_t is:

    a) a string in  the release name which says "3.22"

    b) an integer called 'proto_major' which contains the value 3 but 
the comment next to this field in gps.h says its the API major (which is 
11 in the #define)

    c) an integer called 'proto_minor' which contains the value 14 but 
the comment next to this field in gps.h says its the API minor (which is 
0 in the #define)


So, what what a program has available at run-time I don't see how I can 
ever do a valid check since

    proto_major (value 3) != API major (value 11)  && proto_minor 
(value 14) != API minor (value 0)


Its like I am trying to compare apples with pears ... what am I missing 
here?


I fully understand that if I install matching versions of gpsd/libgps 
everything will work, but what comparisons do I perform to check if 
things are out of step, for example if gpsd has been upgraded but libgps 
has not ... ?



> > I am slightly confused ... is there:
> >
> >       a) just an API version to check; or
> No.
>
> >       b) an API version *and* a protocol version to ckeck?
> Only if you want your code to work.  But the versions mean something.
> So you have to change your code to match the versions.
>
> If you access a gpsd with its matching libgps, then most version
> changes will be invisible to you.  Most of the remaining ones
> will give you compile errors.  What remains will be a few visible
> behavior change.
>
> > which appears to use "API version" interchangeably with "proto
> > version" ?
> They tend to go in tandem, but they can differ.
>
> > Can you advise further?
> Not much I can do without seeing your code.
>
> RGDS
> GARY
> ---------------------------------------------------------------------------
> Gary E. Miller Rellim 109 NW Wilmington Ave., Suite E, Bend, OR 97703
>         gem@rellim.com  Tel:+1 541 382 8588
>
>             Veritas liberabit vos. -- Quid est veritas?
>      "If you can't measure it, you can't improve it." - Lord Kelvin