// This method should be overridden in all subclasses to avoid casting the result when calling it.
// For the default one, the MPI_*_NULL returned is assumed to be NULL.
static F2C* f2c(int id);
// This method should be overridden in all subclasses to avoid casting the result when calling it.
// For the default one, the MPI_*_NULL returned is assumed to be NULL.
static F2C* f2c(int id);