ENH: auto-detect otb version from CMakeLists.txt

CMakeLists.txt

@@ -63,10 +63,6 @@ include(OTBModuleRemote)
 
 set(main_project_name ${_OTBModuleMacros_DEFAULT_LABEL})
 
-#Please also update PACKAGE_VERSION var in SuperBuild/CMake/External_package.cmake
-#when updating values below. There is no direct way to get OTB_VERSION_STRING value
-#there.. other than I use an file(READ ... REGEX) option.
-#Manually updating PACKAGE_VERSION seems way better than using read file and stuff.
 #-----------------------------------------------------------------------------
 # OTB version number.
 set(OTB_VERSION_MAJOR "5")

SuperBuild/CMake/External_package.cmake

 
 message(STATUS "Setup OTB Packaging...")
 
-set(PACKAGE_VERSION 5.2.0)
+set(PACKAGE_VERSION)
+
+if(EXISTS "${CMAKE_SOURCE_DIR}/../CMakeLists.txt")
+  file(STRINGS "${CMAKE_SOURCE_DIR}/../CMakeLists.txt" _otb_version_vars   REGEX "set\\\(OTB_VERSION_")
+  file(WRITE  ${CMAKE_BINARY_DIR}/CMakeFiles/version_vars.cmake "#OTB version\n")
+  foreach(_otb_version_var ${_otb_version_vars})
+    file(APPEND ${CMAKE_BINARY_DIR}/CMakeFiles/version_vars.cmake "${_otb_version_var}\n")
+  endforeach()
+  include(${CMAKE_BINARY_DIR}/CMakeFiles/version_vars.cmake)
+  if(OTB_VERSION_STRING)
+    set(PACKAGE_VERSION ${OTB_VERSION_STRING})
+  else()
+    message(FATAL_ERROR "Packaging: Cannot find OTB_VERSION_STRING!")
+  endif()
+else()
+  message(FATAL_ERROR "Packaging: File '${CMAKE_SOURCE_DIR}/../CMakeLists.txt' does not exists")
+endif()
+
 set(PACKAGE_NAME OTB)
 set(PACKAGE_LONG_NAME OrfeoToolBox)