This small example demonstrates how to pass a communicator from Python to Rust and use it with rsmpi from within Rust.
It is developed so that maturin can automatically generate the correct cffi bindings. To compile just call
maturin develop -b cffi
This compiles the Rust part, generates a pip module and installs
the pip module. To execute the code create a small file called
say_rank.py which contains
from mpi4py_with_rsmpi import say_rank, COMM
say_rank(COMM)
and call it for example with
mpirun -n 4 python say_rank.py
This will initialize the MPI system within Python. But the rank of each process is printed out from Rust with rsmpi.