%gtkdocentities; ]> The purpose of libfeedback is to make it simple to supply audible, haptic and visual feedback to the user. This is done by notifying a &feedback_daemon; over DBus that a certain event happened and the daemon selects the appropriate feedbacks (such as a buzzing haptic motor or playing an audio file) based on the user session's current feedback profile, feedback theme and available hardware. Events are identified by strings like message-new-sms or message-new-sms. The available event names are described in the &event_naming_spec;. &package; provides synchronous and asynchronous APIs to trigger and stop feedback for these events and is usable from other languages than C by GObject introspection. Like other GNOME libraries, &package_string; uses pkg-config to provide compiler options. The package name is "&package_ver_str;". So in your configure.ac script, you might specify something like: PKG_CHECK_MODULES(LIBFEEDBACK, [&package_string;-&package_api_version;]) AC_SUBST(LIBFEEDBACK_CFLAGS) AC_SUBST(LIBFEEDBACK_LIBS) If using Meson/Ninja use a dependency('&package_string;-&package_api_version;') dependency. The "&package_api_version;" in the package name is the "API version" (indicating "the version of the &package_string; API that first appeared in version &package_api_version;") and is essentially just part of the package name. When using the Meson build system you can declare a dependency like dependency(libfeedback-0.0') Since the library is young and is still changing a lot, in order to use it you are required to acknowledge that your are using an unstable API. To do so, LIBFEEDBACK_USE_UNSTABLE_API must be defined for compilation to succeed. From C code or any compatible language, you can prefix your inclusion of the &package_string; header like so: #define LIBFEEDBACK_USE_UNSTABLE_API #include <libfeedback.h> Including individual headers rather than libfeedback.h is not recommended. You can also acknowledge this with the definition option of your C compiler, like -DFEEDBACK_USE_UNSTABLE_API. This is required from Vala. To use &package_name; from Vala, you must define the acknowledgment in C via -X -DFEEDBACK_USE_UNSTABLE_API. If your build system uses a two pass compilation and hence your Vala compiler outputs C (Meson, Automake, or using the --ccode Vala compiler option trigger that) then you must add -DLIBFEEDBACK_USE_UNSTABLE_API to your C compiler arguments instead.