From 5b116a4a67fbe930fdc01913537f1ed743e59a05 Mon Sep 17 00:00:00 2001
From: Ellon Mendes <ellon.mendes@laas.fr>
Date: Sat, 28 Nov 2015 00:34:48 +0100
Subject: [PATCH] Add option to chose target python version to create module

---
 cmake/GtsamPythonWrap.cmake       | 13 +++++++------
 python/CMakeLists.txt             | 29 ++++++++++++++++++++++++-----
 python/handwritten/CMakeLists.txt |  2 +-
 3 files changed, 32 insertions(+), 12 deletions(-)

diff --git a/cmake/GtsamPythonWrap.cmake b/cmake/GtsamPythonWrap.cmake
index c23ee783d..f7d468940 100644
--- a/cmake/GtsamPythonWrap.cmake
+++ b/cmake/GtsamPythonWrap.cmake
@@ -1,4 +1,5 @@
 #Setup cache options
+set(GTSAM_PYTHON_VERSION "2.7" CACHE STRING "Version of python used to build the wrapper")
 set(GTSAM_BUILD_PYTHON_FLAGS "" CACHE STRING "Extra flags for running Matlab PYTHON compilation")
 set(GTSAM_PYTHON_INSTALL_PATH "" CACHE PATH "Python toolbox destination, blank defaults to CMAKE_INSTALL_PREFIX/borg/python")
 if(NOT GTSAM_PYTHON_INSTALL_PATH)
@@ -7,13 +8,13 @@ endif()
 
 #Author: Paul Furgale Modified by Andrew Melim
 function(wrap_python TARGET_NAME PYTHON_MODULE_DIRECTORY)
-  # Boost
-  find_package(Boost COMPONENTS python filesystem system REQUIRED)
-  include_directories(${Boost_INCLUDE_DIRS})
+  # # Boost
+  # find_package(Boost COMPONENTS python filesystem system REQUIRED)
+  # include_directories(${Boost_INCLUDE_DIRS})
 
-  # Find Python
-  FIND_PACKAGE(PythonLibs 2.7 REQUIRED)
-  INCLUDE_DIRECTORIES(${PYTHON_INCLUDE_DIRS})
+  # # Find Python
+  # FIND_PACKAGE(PythonLibs 2.7 REQUIRED)
+  # INCLUDE_DIRECTORIES(${PYTHON_INCLUDE_DIRS})
 
   IF(APPLE)
     # The apple framework headers don't include the numpy headers for some reason.
diff --git a/python/CMakeLists.txt b/python/CMakeLists.txt
index 0fcb1fc28..4fe0d8cf9 100644
--- a/python/CMakeLists.txt
+++ b/python/CMakeLists.txt
@@ -1,12 +1,31 @@
-# Obtain Dependencies
-# Boost Python
-find_package(Boost COMPONENTS python REQUIRED)
-include_directories(${Boost_INCLUDE_DIRS})
+# The code below allows to clear the PythonLibs cache if we change GTSAM_PYTHON_VERSION
+# Inspired from the solution found here: http://blog.bethcodes.com/cmake-tips-tricks-drop-down-list
+if((NOT DEFINED GTSAM_LAST_PYTHON_VERSION))
+	set(GTSAM_LAST_PYTHON_VERSION ${GTSAM_PYTHON_VERSION} CACHE STRING "Python version used in the last build")
+	mark_as_advanced(FORCE GTSAM_LAST_PYTHON_VERSION)
+endif()
+if((NOT (${GTSAM_PYTHON_VERSION} MATCHES ${GTSAM_LAST_PYTHON_VERSION})))
+	unset(PYTHON_INCLUDE_DIR CACHE)
+	unset(PYTHON_INCLUDE_DIR2 CACHE)
+	unset(PYTHON_LIBRARY CACHE)
+	unset(PYTHON_LIBRARY_DEBUG CACHE)
+	set(GTSAM_LAST_PYTHON_VERSION ${GTSAM_PYTHON_VERSION} CACHE STRING "Updating python version used in the last build" FORCE)
+endif()
+
+# Be sure that python version can be found by FindPythonLibs.cmake
+# See: http://stackoverflow.com/a/15660652/2220173
+set(Python_ADDITIONAL_VERSIONS ${GTSAM_PYTHON_VERSION})
 
 # Find Python
-find_package(PythonLibs 2.7 REQUIRED)
+find_package(PythonLibs ${GTSAM_PYTHON_VERSION} REQUIRED)
 include_directories(${PYTHON_INCLUDE_DIRS})
 
+# Boost Python
+string(REPLACE "." "" PYTHON_VERSION_NUMBER ${GTSAM_PYTHON_VERSION}) # Remove '.' from version
+string(SUBSTRING ${PYTHON_VERSION_NUMBER} 0 2 PYTHON_VERSION_NUMBER) # Trim version number to 2 digits
+find_package(Boost COMPONENTS python-py${PYTHON_VERSION_NUMBER} REQUIRED)
+include_directories(${Boost_INCLUDE_DIRS})
+
 # Numpy_Eigen
 include_directories(${CMAKE_SOURCE_DIR}/gtsam/3rdparty/numpy_eigen/include/)
 
diff --git a/python/handwritten/CMakeLists.txt b/python/handwritten/CMakeLists.txt
index 1090ef9cf..893fbae71 100644
--- a/python/handwritten/CMakeLists.txt
+++ b/python/handwritten/CMakeLists.txt
@@ -18,7 +18,7 @@ set_target_properties(${moduleName}_python PROPERTIES
     OUTPUT_NAME         ${moduleName}_python
     CLEAN_DIRECT_OUTPUT 1)
 
-target_link_libraries(${moduleName}_python ${Boost_PYTHON_LIBRARY} ${PYTHON_LIBRARY} ${gtsamLib}) #temp
+target_link_libraries(${moduleName}_python ${Boost_PYTHON-PY${PYTHON_VERSION_NUMBER}_LIBRARY} ${PYTHON_LIBRARY} ${gtsamLib}) #temp
 
 # On OSX and Linux, the python library must end in the extension .so. Build this
 # filename here.