python *args *kwargs

def foo(*args, **kwargs):
    print 'args = ', args
    print 'kwargs = ', kwargs

if __name__ == '__main__':
    foo(1, 2, 3, 4)
    foo(a=1, b=2, c=3)
    foo(1, 2, 3, 4, a=1, b=2, c=3)
    foo('a', 1, None, a=1, b='2', c=3)

args =  (1, 2, 3, 4) 
kwargs =  {} 
--------------------------------------- 
args =  () 
kwargs =  {'a': 1, 'c': 3, 'b': 2} 
--------------------------------------- 
args =  (1, 2, 3, 4) 
kwargs =  {'a': 1, 'c': 3, 'b': 2} 
--------------------------------------- 
args =  ('a', 1, None) 
kwargs =  {'a': 1, 'c': 3, 'b': '2'} 
---------------------------------------

这两个是python中的可变参数。args表示任何多个无名参数，它是一个tuple；**kwargs表示关键字参数，它是一个dict。并且同时使用args和kwargs时，必须*args参数列要在kwargs前.