Quarrel: WSGI-style routing for command line tools, in about 50 lines

example.py

import sys
from quarrel import Quarrel

@Quarrel("multiply", int, int)
@Quarrel("multiply", int)
def multiply_int(a, b = 2):
  print(a * b)

@Quarrel("greet", str)
def greet(name):
  print("Hello, {}!".format(name))

@Quarrel("pick", list)
def pick(selection):
  import random
  print(random.choice(selection))

@Quarrel(None)
@Quarrel("help")
def help():
  print("Welcome to the Quarrel sample!")
  print("Try:")
  print("example.py multiply 5") # 10
  print("example.py multiply 5 5") # 25
  print("example.py greet world") # Hello, world!
  print("example.py pick one two three") # one, two, or three

if __name__ == "__main__":
  if not Quarrel.route(sys.argv[1:]):
    print(help())

quarrel.py

from inspect import isclass

class Quarrel(object):
	routes = []
	
	def __init__(self, *args):
		for arg in args:
			if not (isclass(arg) or isinstance(arg, basestring) or arg is None):
				raise ValueError()
		
		self.args = args
	
	def __call__(self, func):
		Quarrel.routes.append((self.args, func))
		return func
	
	@staticmethod
	def route(args):
		if len(args) == 0:
			for pattern, func in Quarrel.routes:
				if len(pattern) == 1 and pattern[0] is None:
					func()
					return True
		else:
			for pattern, func in Quarrel.routes:
				if pattern[-1] != list and len(pattern) != len(args):
					continue
				
				match = True
				func_args = []
				
				for i, part in enumerate(pattern):
					if isclass(part):
						if part == bool:
							func_args.append(True if args[i].lower() in ["true", "yes", "y"] else False)
						elif part == list:
							func_args.append(args[i:])
							break
						else:
							try:
								func_args.append(part(args[i]))
							except ValueError:
								match = False
								break
					elif isinstance(part, basestring):
						if part != args[i]:
							match = False
							break
				
				if match:
					func(*func_args)
					return True
		return False