Add an extension point to allow inserting external libraries and defi…

…nitions

.gitignore

@@ -120,3 +120,6 @@ nbproject
 .dir-locals.el
 Build.props
 Directory.Build.props
+
+# optional folder for extension projects
+/ext

CMakeLists.txt

@@ -62,6 +62,7 @@ option(QL_USE_STD_CLASSES "Enable all QL_USE_STD_ options" OFF)
 option(QL_USE_STD_SHARED_PTR "Use standard smart pointers instead of Boost ones" OFF)
 option(QL_USE_STD_FUNCTION "Use std::function and std::bind instead of Boost ones" OFF)
 option(QL_USE_STD_TUPLE "Use std::tuple instead of boost::tuple" OFF)
+set(QL_EXTRA_LINK_LIBRARIES "" CACHE STRING "Optional extra link libraries to add to QuantLib")
 
 # Convenience option to activate all STD options
 if (QL_USE_STD_CLASSES)
@@ -204,6 +205,11 @@ endif()
 include(CTest)
 include(Platform)
 
+# extension subdirectory if it exists (hook for external projects)
+if(EXISTS ${PROJECT_SOURCE_DIR}/ext AND EXISTS ${PROJECT_SOURCE_DIR}/ext/CMakeLists.txt)
+    add_subdirectory(ext)
+endif()
+
 # Add subdirectories
 add_subdirectory(ql)
 if (QL_BUILD_EXAMPLES)

ql/CMakeLists.txt

@@ -2332,6 +2332,10 @@ target_compile_definitions(ql_library PRIVATE
 target_compile_options(ql_library PRIVATE
     ${OpenMP_CXX_FLAGS})
 
+if(NOT "${QL_EXTRA_LINK_LIBRARIES}" STREQUAL "")
+    target_link_libraries(ql_library PUBLIC ${QL_EXTRA_LINK_LIBRARIES})
+endif()
+
 target_include_directories(ql_library PUBLIC
     $<BUILD_INTERFACE:${PROJECT_BINARY_DIR}>
     $<BUILD_INTERFACE:${PROJECT_SOURCE_DIR}>