add Sigslot as a generic publish/subscribe framework

The intention is to use this instead of adding more and more methods to
the coVRPlugin base class.

Usage examples: https://github.com/palacaze/sigslot

deviceDiscovery is the first user of this.

Author: aumuell

.gitmodules

@@ -32,3 +32,6 @@
 [submodule "src/3rdparty/crow"]
 	path = src/3rdparty/crow
 	url = https://github.com/CrowCpp/Crow.git
+[submodule "src/3rdparty/sigslot"]
+	path = src/3rdparty/sigslot
+	url = https://github.com/palacaze/sigslot.git

src/3rdparty/CMakeLists.txt

@@ -89,3 +89,12 @@ endif()
 
 set(CROW_USE_BOOST ON CACHE BOOL "Use Boost.Asio for Crow" FORCE)
 add_subdirectory(crow)
+
+#include(sigslot/cmake/SigSlotUtils.cmake)
+add_library(PalSigslot INTERFACE sigslot/include/sigslot/signal.hpp)
+target_include_directories(PalSigslot INTERFACE
+    $<BUILD_INTERFACE:${CMAKE_CURRENT_LIST_DIR}/sigslot/include>
+    $<INSTALL_INTERFACE:include>
+)
+install(TARGETS PalSigslot EXPORT covise-targets)
+add_library(Pal::Sigslot ALIAS PalSigslot)

src/3rdparty/sigslot

@@ -312,6 +312,8 @@ TARGET_LINK_LIBRARIES(${COVERKERNEL_TARGET} coOpenVRUI coOSGVRUI coMessages coOp
    ${COVISE_VRBCLIENT_LIBRARY} ${COVISE_GRMSG_LIBRARY} ${COVISE_UTIL_LIBRARY} ${COVISE_GPU_LIBRARIES} ${COVISE_NET_LIBRARY}
    ${XERCESC_LIBRARIES} ${OPENSCENEGRAPH_LIBRARIES} ${TIFF_LIBRARIES} ${CMAKE_THREAD_LIBS_INIT} ${EXTRA_LIBS})
 
+TARGET_LINK_LIBRARIES(${COVERKERNEL_TARGET} Pal::Sigslot)
+
 IF(CURL_FOUND)
   USING(CURL)
   add_dependencies(${COVERKERNEL_TARGET} coCurlHTTPClient)

src/OpenCOVER/cover/CMakeLists.txt

@@ -103,6 +103,12 @@ namespace opencover
 	    }
     }
     toAdd.clear();
+    auto firstNew = devices.end() - numToAdd;
+    for (int i = 0; i < numToAdd; i++)
+    {
+        deviceAdded(*firstNew);
+        ++firstNew;
+    }
     }
     void deviceDiscovery::run()
     {

src/OpenCOVER/cover/input/deviceDiscovery.cpp

@@ -22,6 +22,8 @@
 #include <OpenThreads/Mutex>
 #include <util/UDPComm.h>
 
+#include <sigslot/signal.hpp>
+
 
 namespace opencover
 {
@@ -56,6 +58,7 @@ namespace opencover
 
         // only to be used from main thread
         const std::vector<const deviceInfo *> &getDevices() const;
+        sigslot::signal<const deviceInfo *> deviceAdded;
 
     private:
         std::vector<const deviceInfo *> devices;