From 046736e45d3d4637b1fcf3ff19d268c7efa6375e Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?H=C3=A5kon=20H=C3=A6gland?= <hakon.hagland@gmail.com>
Date: Tue, 7 Jun 2022 08:19:15 +0200
Subject: [PATCH] Make Python opm package a namespace package

Convert the Python opm package from a regular package to a namespace
package such that opm-simulators can contribute to the package from a
different filesystem path. In this way, the two packages opm.simulators
and opm.io (for example) can have a different parent filesystem path.
---
 CMakeLists.txt                    |  6 ++++++
 python/opm/__init__.py            |  0
 python/opm/simulators/__init__.py | 15 ---------------
 3 files changed, 6 insertions(+), 15 deletions(-)
 delete mode 100644 python/opm/__init__.py
 delete mode 100644 python/opm/simulators/__init__.py

diff --git a/CMakeLists.txt b/CMakeLists.txt
index d7ad834da..9cfe41712 100644
--- a/CMakeLists.txt
+++ b/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
diff --git a/python/opm/__init__.py b/python/opm/__init__.py
deleted file mode 100644
index e69de29bb..000000000
diff --git a/python/opm/simulators/__init__.py b/python/opm/simulators/__init__.py
deleted file mode 100644
index 66220f553..000000000
--- a/python/opm/simulators/__init__.py
+++ /dev/null
@@ -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
-