A resource can be specified with the syntax:
[addon=ADDON_ID]relative/path
Such a resource corresponds to the file $addon_base_path/relative/path
for the specific add-on whose identifier is ADDON_ID.
If the particular add-on isn't registered, looking up such a resource
throws sg_exception.
(everything described here lives in the namespace flightgear::addons)
New classes: Author, Maintainer, and Contact. Author and Maintainer
derive from Contact. For each contact, the following can be defined in
addon-metadata.xml: name, email, and url. See [1] for details about the
syntax and usage policy. Nasal bindings have been updated accordingly,
there are three new ghosts: addons.Contact, addons.Author and
addons.Maintainer.
The enum class UrlType has two new members: author and maintainer. The
Addon::getUrls() method has a new signature:
std::multimap<UrlType, QualifiedUrl> getUrls() const;
because non-empty 'url' fields for authors and maintainers contribute to
the result, and there can be an arbitrary number of authors and an
arbitrary number of maintainers defined for a given add-on---therefore,
std::map can't be used anymore.
Finally, QualifiedUrl has a new field (detail) which stores the author
name (resp. maintainer name) when the QualifiedUrl type is
UrlType::author (resp. UrlType::maintainer). Currently, this 'detail'
field is not used for other URL types, but this could be changed if
desired.
[1] https://sourceforge.net/p/flightgear/fgdata/ci/next/tree/Docs/README.add-ons
flightgear::addons::shared_ptr_traits allows one to easily switch for
instance from an SGSharedPtr<T> to an std::shared_ptr<T> for "all" uses
of a particular T, and automatically have std::make_shared<T>(...) used
instead of SGSharedPtr<T>(new T(...)) when creating a shared instance of
T. This is interesting because std::make_shared<T>() allocates all
needed memory as one block, whereas std::shared_ptr<T>(new T(args...))
would perform at least two allocations (one for the object T and one for
the control block of the shared pointer).
This is done via static methods (one for each kind of smart pointer):
shared_ptr_traits<SGSharedPtr<T>>::makeStrongRef()
shared_ptr_traits<std::shared_ptr<T>>::makeStrongRef()
that forward their arguments in the same way as std::make_shared<T>().
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/
