Misunderstanding kwargs?

[deanhystad]

def test(*args, **kvargs):
    print(type(args), args, type(kvargs), kvargs)

test('this', 'is', a='a', test='test')
test(*('this', 'is'), **{'a':'a', 'test':'test'})

Output:
<class 'tuple'> ('this', 'is') <class 'dict'> {'a': 'a', 'test': 'test'}
<class 'tuple'> ('this', 'is') <class 'dict'> {'a': 'a', 'test': 'test'}

So args is a tuple and kvargs is a dictionary.
*(1, 2, 3) extracts the values from the tuple and provides them as separate items instead of a collection. This is called "unpacking". You can also unpack a dictionary though what is returned is less obvious.

You don't have to understand how kvargs works to use it. Even though kvargs is a dictionary you should not be treating it as a dictionary. To extract values from *args and **kvargs you specify arguments for your function:

def leftovers(*args, **kvargs):
    print(args, kvargs)

def filter(a, *args, b='thing', **kvargs):
    leftovers(*args, **kvargs)

filter(1, 2, b=3, c=4)

Output:
(2,) {'c': 4}

The function "filter" consumes the first position argument and the 'b' keyword argument. The remaining arguments can be passed on to the "leftovers" function. This is so much simpler than:

def leftovers(*args, **kvargs):
    print(args, kvargs)

def filter(*args, **kvargs):
    a = args[0]
    b = kvargs['b']
    del kvargs['b']
    leftovers(args[1:], **kvargs)

filter(1, 2, b=3, c=4)