WARNING: just a temporary development for the TRIQS project, not intended for distribution.

Goal
----

A demo code to call Python from a C (or Fortran code).

- execute_py.h, execute_py.c : 
  the function to open a new interpreter, run a script in it and close it

- main.c : a small demo code, which : 
   
   - opens mpi in C, does a basic operation with it
   - call Python, which itself launch mpi4py and use it a bit
   - redo some mpi after the Python is finalized, to check mpi is not affected.

- test.py : the python script for the test

NB : one can also split the function in 3 functions (init, run, finalize) 
to keep the interpreter alive between calls. Is it useful ?

- to use it form fortran, call the execute_py with 2 strings...
  (todo)

Compilation
------------

- This is a C code (not C++), you need to compile with a C compiler.
  (to have a mangling compatible with fortran).

- You need to link to dl (for dlopen), and mpi (for the test)

- Compilation instructions.

 * OS X : 
   clang execute_py.c main.c  -ldl  -lmpi
 

Run
----

./a.out requires two arguments:

 - the location of the Python shared library (.so on Linux, .dylib on OS X).
 - the name of the script

e.g.

kondo:~/execute_python (master)$ mpirun -np 4 ./a.out /usr/local/install/python-2.7.5/lib/libpython2.7.so ./test.py 
Hello world! I'm process 0 out of 4 processes
Hello world! I'm process 1 out of 4 processes
Hello world! I'm process 2 out of 4 processes
Hello world! I'm process 3 out of 4 processes
Python I am node  2
Python I am node  3
Python I am node  0
Python I am node  1
Hello again ! I'm process 1 out of 4 processes
Hello again ! I'm process 3 out of 4 processes
Hello again ! I'm process 0 out of 4 processes
Hello again ! I'm process 2 out of 4 processes