CommandLoop module in python

http://littlelanguages.com/web/software/python/modules/cmdloop.py

Here's a python module which provides a base class for writing simple interactive command loop environments. It makes use of python 2.4 decorators to describe the command functions.

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()