Merge pull request #3040 from hakonhagland/python_nsp2

Make the Python `opm` package a namespace package

CMakeLists.txt

@@ -184,6 +184,8 @@ if (OPM_ENABLE_PYTHON)
     endif()
     set(Python3_EXECUTABLE ${PYTHON_EXECUTABLE})
     set(Python3_LIBRARIES ${PYTHON_LIBRARIES})
+    set(Python3_VERSION "${PYTHON_VERSION_STRING}"})
+    set(Python3_VERSION_MINOR ${PYTHON_VERSION_MINOR})
   else()
     # Be backwards compatible.
     if(PYTHON_EXECUTABLE AND NOT Python3_EXECUTABLE)
@@ -210,6 +212,10 @@ if (OPM_ENABLE_PYTHON)
         "Either use \"apt-get install python3-setuptools\" (on Debian/Ubuntu) "
         "or \"pip install setuptools\"")
     endif()
+    if(Python3_VERSION_MINOR LESS 3)
+      # Python native namespace packages requires python >= 3.3
+      message(SEND_ERROR "OPM requires python >= 3.3 but only version ${Python3_VERSION} was found")
+    endif()
 
     # Compatibility settings for PythonInterp and PythonLibs
     # used e.g. in FindCwrap, pybind11

python/opm/simulators/__init__.py

@@ -1,15 +0,0 @@
-# When using opm-simulators in combination with opm-common, the
-#   opm-simulators pybind11 module is placed in a package opm2, i.e. opm2.simulators.
-#   This is done to avoid conflict with the opm-common package prefix opm.
-#   The following is hack to avoid having to write
-#
-#  from opm2.simulators import BlackOilSimulator
-#  from opm.io.parser import Parser
-#  #....
-#
-#   when it would be more natural to use the "opm" prefix instead of "opm2"
-#   to import the BlackOilSimulator also. It assumes that PYTHONPATH includes
-#   the install directory for the pybind11 python module for opm2.simulators
-
-from opm2.simulators import BlackOilSimulator
-