[python] *args **kwargs

Source code is as below:

def func(*args,**kwargs):
    print 'args=',args
    print 'kwargs=',kwargs
    print '_'*30

def main():
    func(1,2,3,4)
    func(a=1,b=2,c=3)
    func(1,2,3,4,a=1,b=2,c=3)
    func('a',1,None,a=1,b='2',c=3)

if __name__=='__main__':
    main()

When the above code is executed,it produces the following result.

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'}
______________________________

*args representing a tuple()

**kwargs representing a dict()

*args and **kwagrs are used simultaneously,it should put *args as first argument followed by the **kwargs, instead,if the order is reversed,the error exception will be raised ,it should be like this:“SyntaxError: non-keyword arg after keyword arg”。

Tips and tricks:

one another way of using this is to create and generate dict()

def my_dict(**kwargs):

　　return kwargs

print my_dict(a=1,b=2,c=3)

{a=1,b=2,c=3}

 

dict(a=1,b=2,c=3) can generate a dict as well.