pytriqs: add option to use mpi4py instead of boost.python.mpi

- to choose mpi4py over boost.python.mpi, pass -DPython_use_mpi4py=ON

- boost.mpi stays the default for python, but
  adding the possibility of using mpi4py instead.

- Due to numerous pbs on recent OS X + brew installation.
  boost.mpi does not work (crash in openmpi ??), mpi4py does

- the pytriqs/utility/mpi.py is now configured by the cmake (like
  version.py) to prepare one of the two possibilities.

- TODO:  not tested carefully : to be done in other machines.

pytriqs/CMakeLists.txt

@@ -1,3 +1,10 @@
+option(Python_use_mpi4py "Use mpi4py instead of boost.mpi" OFF)
+if (Python_use_mpi4py) 
+ SET (TRIQS_PYTHON_MPI_USE_MPI4PY 1)
+else()
+ SET(TRIQS_PYTHON_MPI_USE_MPI4PY 0)
+endif()
+
 # Create a temporary copy of the python modules so that we can run before installation with the test
 FILE(GLOB_RECURSE all_py_files RELATIVE ${CMAKE_SOURCE_DIR}/pytriqs *.py )
 SET(py_copy_tar  ${CMAKE_BINARY_DIR}/py_copy.tar)
@@ -13,6 +20,7 @@ SET(PYTHON_SOURCES
  )
 
 configure_file(${CMAKE_CURRENT_SOURCE_DIR}/version.py.in ${CMAKE_CURRENT_BINARY_DIR}/version.py)
+configure_file(${CMAKE_CURRENT_SOURCE_DIR}/utility/mpi.py.in ${CMAKE_CURRENT_BINARY_DIR}/utility/mpi.py)
 
 install (FILES ${PYTHON_SOURCES} DESTINATION ${TRIQS_PYTHON_LIB_DEST})
 

pytriqs/utility/CMakeLists.txt

@@ -3,7 +3,9 @@ SET(PYTHON_SOURCES
   ${CMAKE_CURRENT_SOURCE_DIR}/__init__.py
   ${CMAKE_CURRENT_SOURCE_DIR}/dichotomy.py
   ${CMAKE_CURRENT_SOURCE_DIR}/dist_on_nodes.py
-  ${CMAKE_CURRENT_SOURCE_DIR}/mpi.py
+  ${CMAKE_CURRENT_BINARY_DIR}/mpi.py
+  ${CMAKE_CURRENT_BINARY_DIR}/mpi_mpi4py.py
+  ${CMAKE_CURRENT_BINARY_DIR}/mpi_boost.py
   ${CMAKE_CURRENT_SOURCE_DIR}/redirect.py
 )
 

pytriqs/utility/mpi.py.in

@@ -0,0 +1,25 @@
+################################################################################
+#
+# TRIQS: a Toolbox for Research in Interacting Quantum Systems
+#
+# Copyright (C) 2013 by M. Ferrero, O. Parcollet
+#
+# TRIQS is free software: you can redistribute it and/or modify it under the
+# terms of the GNU General Public License as published by the Free Software
+# Foundation, either version 3 of the License, or (at your option) any later
+# version.
+#
+# TRIQS is distributed in the hope that it will be useful, but WITHOUT ANY
+# WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
+# FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
+# details.
+#
+# You should have received a copy of the GNU General Public License along with
+# TRIQS. If not, see <http://www.gnu.org/licenses/>.
+#
+################################################################################
+
+if @TRIQS_PYTHON_MPI_USE_MPI4PY@ : 
+    from mpi_mpi4py import *
+else:
+    from mpi_boost import *