Change Cython version checking to match the way Cython is used (through import, rather than cython executable). Prevents a problem when PYTHON passed in to CMake differs from the default python and cython found in the path. Also, much simpler than finding cython and asking it for the version.

Former-commit-id: 312f1d6

Author: mattr1

cmake/FindCython.cmake

@@ -8,13 +8,24 @@ function(get_filename_components DEST ITEMS PART)
   set(${DEST} ${${DEST}} PARENT_SCOPE)
 endfunction()
 
+function(check_cython_version VERSION)
+  # We use the Cython library directly within Python, make sure it is installed
+  # and meets the minimum version required.
+  execute_process(COMMAND ${PYTHON} -c "import Cython; print Cython.__version__;" OUTPUT_VARIABLE CYTHON_VERSION)
+  if(${CYTHON_VERSION} VERSION_LESS ${VERSION})
+    message(FATAL_ERROR "DyNet needs at least Cython version ${VERSION}, found verson ${CYTHON_VERSION}")
+  else()
+    message(STATUS "Found Cython version ${CYTHON_VERSION}")
+  endif()
+endfunction()
+
 if(!PYTHON)
   find_program(PYTHON "python")
 endif()
 
 if(PYTHON)
-  # look for Cython
-  find_package(Cython REQUIRED)
+  # Verify Cython is installed with the given minimum version
+  check_cython_version(0.23)
 
   # Things to copy the files
   file(GLOB DepFiles ${CMAKE_CURRENT_SOURCE_DIR}/dynet.py