python args和kwargs

args和kwargs组合起来可以传入任意的参数，这在参数未知的情况下是很有效的，同时加强了函数的可拓展性。

def test_kwargs(first, *args, **kwargs):
    print('Required argument: ', first)
    print(type(kwargs))
    for v in args:
        print ('Optional argument (args): ', v)
    for k, v in kwargs.items():
        print ('Optional argument %s (kwargs): %s' % (k, v))

test_kwargs(1, 2, 3, 4, k1=5, k2=6)

结果

Required argument:  1
<class 'dict'>
Optional argument (args):  2
Optional argument (args):  3
Optional argument (args):  4
Optional argument k1 (kwargs): 5
Optional argument k2 (kwargs): 6

与上边相比较，test_kwargs(1, 2, 3, 4, k1=5)少了k2=6

*args传输位置参数，**kwargs 传输的是字典参数

def test_kwargs(first, *args, **kwargs):
    print('Required argument: ', first)
    print(type(kwargs))
    for v in args:
        print ('Optional argument (args): ', v)
    for k, v in kwargs.items():
        print ('Optional argument %s (kwargs): %s' % (k, v))

test_kwargs(1, 2, 3, 4, k1=5)

结果

Required argument:  1
<class 'dict'>
Optional argument (args):  2
Optional argument (args):  3
Optional argument (args):  4
Optional argument k1 (kwargs): 5