*args and **kwargs

[Andrew Lusk]

"Dan" <dan at cox.com> writes:
> I am still pretty new on Python and have been working with it for 5 months.
> I ran across some source code that has these constructs.  They look like C
> pointers but most likely aren't.  I can't find explanations to them in
> reference books but have only seen them on function declarations in the
> sources.  Can anyone give a brief explanation or provide a pointer link to
> an explanation?

*args is for multiple arguments.

>>> def foo(*args):
...    print args
... 
>>> foo(1,2,3,4,5)
(1, 2, 3, 4, 5)

So it treats its arguments as a tuple.

**args is for keyword arguments.

>>> def foo2(**args):
...     print args
... 
>>> foo2(a=1,b=2,c=[])
{'a': 1, 'c': [], 'b': 2}

So you can send in keyval pairs and it will get a dictionary.  Useful
for having multiple unordered optional arguments.

--Andrew