Code available here: http://littlelanguages.com/web/software/python/modules/cmdloop.py Base class for writing simple interactive command loop environments. CommandLoop provides a base class for writing simple interactive user environments. It is designed around sub-classing, has a simple command parser, and is trivial to initialize. Here is a trivial little environment written using CommandLoop: import cmdloop class Hello(cmdloop.CommandLoop): PS1='hello>' @cmdloop.aliases('hello', 'hi', 'hola') @cmdloop.shorthelp('say hello') @cmdloop.usage('hello TARGET') def helloCmd(self, flags, args): ''' Say hello to TARGET, which defaults to 'world' ''' if flags or len(args) != 1: raise cmdloop.InvalidArguments print >> self.OUT, 'Hello %s!' % args[0] @cmdloop.aliases('quit') def quitCmd(self, flags, args): ''' Quit the environment. ''' raise cmdloop.HaltLoop Hello().runLoop() Here's a more complex example: import cmdloop class HelloGoodbye(cmdloop.CommandLoop): PS1='hello>' def __init__(self, default_target = 'world'): self.default_target = default_target self.target_list = [] @cmdloop.aliases('hello', 'hi', 'hola') @cmdloop.shorthelp('say hello') @cmdloop.usage('hello [TARGET]') def helloCmd(self, flags, args): ''' Say hello to TARGET, which defaults to 'world' ''' if flags or len(args) > 1: raise cmdloop.InvalidArguments if args: target = args[0] else: target = self.default_target if target not in self.target_list: self.target_list.append(target) print >> self.OUT, 'Hello %s!' % target @cmdloop.aliases('goodbye') @cmdloop.shorthelp('say goodbye') @cmdloop.usage('goodbye TARGET') def goodbyeCmd(self, flags, args): ''' Say goodbye to TARGET. ''' if flags or len(args) != 1: raise cmdloop.InvalidArguments target = args[0] if target in self.target_list: print 'Goodbye %s!' % target self.target_list.remove(target) else: print >> self.OUT, \ "I haven't said hello to %s." % target @cmdloop.aliases('quit') def quitCmd(self, flags, args): ''' Quit the environment. ''' raise cmdloop.HaltLoop def _onLoopExit(self): if len(self.target_list): self.pushCommands(('quit',)) for target in self.target_list: self.pushCommands(('goodbye', target)) else: raise cmdloop.HaltLoop HelloGoodbye().runLoop()