cli.py

# Registry of commands
_registry = {}

def register(function):
    """Add command to registry."""
    _registry[function.__name__] = function

def mainloop(prompt="> "):
    """Run event loop."""
    import sys
    while True:
        sys.stdout.write(prompt)
        line = sys.stdin.readline()
        if not line:
            # terminate on end of input
            break
        args = line.strip().split()
        if not args:
            # ignore empty lines
            continue
        ambiguous = False
        f = None
        # look for command prefix in registry
        for k in _registry.keys():
            if k.startswith(args[0]):
                if f is not None:
                    ambiguous = True
                    break
                f = _registry[k]
        if ambiguous:
            print ("Error: %s is an "
                  "ambiguous command" % args[0])
        elif f is None:
            print ("Error: %s is an "
                  "unknown command" % args[0])
        else:
            if not f(args[1:]):
                break

usecli.py

def test(args):
    print "test", args
    return True

def tilt(args):
    print "tilt", args
    return True

def verify(args):
    print "verify", args
    return True

def quit(args):
    print "quit"
    return False

import cli
cli.register(test)
cli.register(tilt)
cli.register(verify)
cli.register(quit)
cli.mainloop()
print "Returned from command loop"