[Flightgear-devel] Add-ons: API changes between FG 2017.4 and the upcoming 2018.2

[Florent R. <f.r...@fr...>]

Hi,

In order to make the add-on API nicer, I made changes (FlightGear commit
da961b97f[1] and FGData commit c17d9377f[2]) that require add-on
maintainers to perform the following renamings in their add-on
directory:

  config.xml -> addon-config.xml
  main.nas   -> addon-main.nas

I believe this was the last chance to make the add-on API clean in this
respect without annoying too many people.

The idea is that all files comprising the interface between FG core and
add-ons now start with 'addon-' (like the existing addon-metadata.xml)
so that when you browse an add-on directory, you can easily tell which
files belong to the “FG core <-> add-on” interface and which files
belong to the add-on proper. This will also be beneficial when more
files are added to the “FG core <-> add-on” interface, such as possibly
addon-events.xml in the future.

To summarize the incompatible changes to the add-on API between
FlightGear 2017.4 and the upcoming 2018.2 release:
  - addon-metadata.xml in the add-on directory is now required;
  - config.xml must be renamed to addon-config.xml (and may be absent if
    you don't need its functionality);
  - main.nas must be renamed to addon-main.nas;
  - the main() function from addon-main.nas is now passed the add-on
    ghost (an addons.Addon instance) instead of a path to the add-on
    base directory (in order to get the same path, just use
    addon.basePath where 'addon' is the first parameter of your main()
    function, i.e., the add-on ghost).

For more info on all these points, see $FG_ROOT/Docs/README.add-ons[3].

I've adapted all add-ons present in FGAddon, so only those maintained
elsewhere need the two renamings.

Regards

[1] https://sourceforge.net/p/flightgear/flightgear/ci/da961b97f22925887742bffc19d7b03871e89b49/

[2] https://sourceforge.net/p/flightgear/fgdata/ci/c17d9377f8da51e9ad57dfecb5a3f25f29782d5c/

[3] https://sourceforge.net/p/flightgear/fgdata/ci/next/tree/Docs/README.add-ons

-- 
Florent