I think I'm going to disagree here -- perhaps vim's -c option will
help. See :help -c .
As an example, consider
vim -c "echo 'hello'" -c "sleep 3" -c q
which will run vim, show "hello" in the messages, wait 3 seconds, and
then quit. So, you presumably could
vim -c "call MyFunction()" -c q
and vim will run your function.
Now, I agree with Marc that I don't really know what you mean by running
vim via an "external system call". How do you intend to launch vim? If
by an icon, you presumably could set its "properties" so as to run vim
with the -c arguments as I showed. If you're using cygwin or the
dos-shell, again, you could run vim as shown (you may need to specify
the full path).
I also agree with Marc that you can't really interact with vim via an
external interface other than via the client-server or netbeans
mechanisms (well, mostly not; I've managed to put together something
that lets gdb talk to vim under linux/unix systems).
Regards,
Chip Campbell