其实None对于“魔法”价值观来说要好得多：class Cheese():

def __init__(self, num_holes = None):

if num_holes is None:

...

现在，如果您想完全自由地添加更多参数：class Cheese():

def __init__(self, *args, **kwargs):

#args -- tuple of anonymous arguments

#kwargs -- dictionary of named arguments

self.num_holes = kwargs.get('num_holes',random_holes())

更好地解释*args和**kwargs(您实际上可以更改这些名称)：def f(*args, **kwargs):

print 'args: ', args, ' kwargs: ', kwargs>>> f('a')args: ('a',) kwargs: {}>>> f(ar='a')args: () kwargs:

{'ar': 'a'}>>> f(1,2,param=3)args: (1, 2) kwargs: {'param': 3}