Changes to DD4hepConfig.cmake

Split libraries into DDCore and DDComponents.
One has to explicitely specify the required components in find_package.
See doc/release.notes for more details

cmake/DD4hep.cmake

@@ -34,7 +34,7 @@ endfunction()
 # calls all the function/includes/configurations that are needed to be done to create dd4hep plugins
 #---------------------------------------------------------------------------------------------------
 function ( dd4hep_instantiate_package PackageName )
-  MESSAGE (STATUS "instantiating the dd4hep package ${PackageName}" )
+  MESSAGE (STATUS "Instantiating the DD4hep package ${PackageName}" )
 
   IF ( NOT ${DD4hep_FOUND} )
     MESSAGE ( FATAL "DD4HEP was not found" )

cmake/DD4hepConfig.cmake.in

@@ -50,19 +50,30 @@ INCLUDE( ${DD4hep_ROOT}/cmake/DD4hepMacros.cmake )
 # additional components are set by cmake in variable PKG_FIND_COMPONENTS
 # first argument should be the package name
 if(@DD4HEP_USE_GEANT4@)
-  CHECK_PACKAGE_LIBS(DD4hep DDCore DDSegmentation DDRec DDG4)
-
   #--- if geant 4 was built with CLHEP we need to export this to client packages
   if( @GEANT4_USE_CLHEP@)
     set(GEANT4_USE_CLHEP  1 ) 
   endif()
 
-  set( Geant4_DIR @Geant4_DIR@)
+  set(Geant4_DIR @Geant4_DIR@)
 
-else()
-  CHECK_PACKAGE_LIBS(DD4hep DDCore DDSegmentation DDRec)
 endif()
 
+CHECK_PACKAGE_LIBS(DD4hep DDCore)
+
+IF(DD4hep_FIND_COMPONENTS)
+  MESSAGE( STATUS "Looking for these Components ${DD4hep_FIND_COMPONENTS}" )
+
+  FOREACH(comp ${DD4hep_FIND_COMPONENTS})
+    #CHECK_PACKAGE_LIBS is looking for components too, just need to check if they were found, if requested
+    STRING( TOUPPER ${comp} _ulibname )
+    if(NOT DD4hep_${_ulibname}_FOUND)
+      MESSAGE(FATAL_ERROR "Did not find required component: ${comp}")
+    ENDIF()
+  ENDFOREACH()
+ENDIF()
+
+
 
 ##---- build with Boost ?
 #if(@DD4HEP_USE_BOOST@)

doc/release.notes

@@ -4,6 +4,15 @@ DD4hep  ----  Release Notes
 =================================
 
 
+2015/05/11 Andre Sailer
+-----------------------
+  - CMake updates:
+         - Split libraries into components: use find_package(DD4hep COMPONENTS <component> [...] )
+           to find the components you need.
+         - At the moment there are these components are sensible to link against: DDRec, DDG4, DDEve, DDSegmentation
+	 - To link against the librarie use either DD4hep_COMPONENT_LIBRARIES or DD4hep_<COMPONENT>_LIBRARY,
+	   where <COMPONENT> needs to be replaced by the UPPER case name of the component
+
 2015/05/09 Markus Frank
 -----------------------
   - Allow to access detectors by type from lcdd.