Python args Kwargs The difference between passing parameters

Let's look at an example:

def foo (*args, **kwargs):    print ' args = ', args    print ' Kwargs = ', Kwargs    print '---------------------------- -----------' if __name__ = = ' __main__ ':    foo (1,2,3,4)    foo (a=1,b=2,c=3)    foo (1,2,3,4, a=1,b=2,c=3)    foo (' A ', 1, None, a=1, b= ' 2 ', c=3)

The output results are as follows:

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 '}
---------------------------------------

As you can see, these two are mutable parameters in Python. *args represents any number of nameless arguments, which is a tuple;**kwargs representing the keyword argument, which is a dict. And when using both *args and **kwargs, the parameter column must be *args before **kwargs, such as foo (a=1, b= ' 2 ', c=3, a ', 1, None,), which would prompt a syntax error "SyntaxError: Non-keyword arg after keyword arg ".

Oh, know *args and **kwargs is what it is. There is also a very nice way to create a dictionary:

    def kw_dict (**kwargs):        return Kwargs    print kw_dict (a=1,b=2,c=3) = = {' A ': 1, ' B ': 2, ' C ': 3}

In fact Python has the Dict class, you can use Dict (a=1,b=2,c=3) to create a dictionary.

"Life is short, I use Python." ”

Python args Kwargs The difference between passing parameters