Since the new _storagePath data member internally contains the add-on
id, changing _id after _storagePath has been initialized would make both
data members inconsistent. As changing the add-on id is probably not a
very useful operation, the simplest way to prevent such an inconsistency
from happening is to make Addon's _id data member const (as is already
the case for _storagePath), and thus remove Addon::setId().
Consequently, remove the Addon default constructor too, since add-ons
with an empty id would be ill-formed and couldn't be changed (_id being
const now). This leaves us with one Addon constructor:
Addon(std::string id, AddonVersion version = AddonVersion(),
SGPath basePath = SGPath(), std::string minFGVersionRequired = "",
std::string maxFGVersionRequired = "",
SGPropertyNode* addonNode = nullptr);
Changes to test_AddonManagement.cxx:
- in testAddonVersionSuffix(), fgtest::initTestGlobals() was called
with the wrong test name (not used anyway, but might be in the
future);
- in testAddon():
* rename variable 'm' to 'addon' ('m' used to stand for the old
class name AddonMetadata);
* call fgtest::initTestGlobals() and fgtest::shutdownTestGlobals()
(not technically needed, but cleaner).
This commit adds C++ classes for add-on management, most notably
AddonManager, Addon and AddonVersion. The AddonManager is used to
register add-ons. It relies on an std::map<std::string, AddonRef> to
hold the metadata of each registered add-on (keys of the std::map are
add-on identifiers, and AddonRef is currently SGSharedPtr<Addon>).
Accessor methods are available for:
- retrieving the list of registered or loaded add-ons (terminology
explained in $FG_ROOT/Docs/README.add-ons);
- checking if a particular add-on has already been registered or
loaded;
- for each add-on, obtaining an Addon instance which can be queried
for its name, id, version, base path, the minimum and maximum
FlightGear versions it requires, its base node in the Property Tree,
its order in the load sequence, short and long description strings,
home page, etc.
The most important metadata is made accessible in the Property Tree
under /addons/by-id/<addon-id> and the property
/addons/by-id/<addon-id>/loaded can be checked or listened to, in
order to determine when a particular add-on is loaded. There is also a
Nasal interface to access add-on metadata in a convenient way.
In order to provide this metadata, each add-on must from now on have in
its base directory a file called 'addon-metadata.xml'.
All this is documented in much more detail in
$FG_ROOT/Docs/README.add-ons.
Mailing-list discussion:
https://sourceforge.net/p/flightgear/mailman/message/36146017/
