Python中*args 和**kwargs的用法

Python中*args 和**kwargs的用法
当函数的参数不确定时，可以使用*args 和**kwargs，*args 没有key值，**kwargs有key值。

def fun_var_args(farg, *args):  
    print "arg:", farg  
    for value in args:  
        print "another arg:", value  
  
fun_var_args(1, "two", 3) # *args可以当作可容纳多个变量组成的list  

result:

arg: 1  
another arg: two  
another arg: 3  

**kwargs:

def fun_var_kwargs(farg, **kwargs):  
    print "arg:", farg  
    for key in kwargs:  
        print "another keyword arg: %s: %s" % (key, kwargs[key])  
  
  
fun_var_kwargs(farg=1, myarg2="two", myarg3=3) # myarg2和myarg3被视为key， 感觉**kwargs可以当作容纳多个key和value的dictionary  

result:

arg: 1  
another keyword arg: myarg2: two  
another keyword arg: myarg3: 3  

也可以用下面的形式：

def fun_var_args_call(arg1, arg2, arg3):  
    print "arg1:", arg1  
    print "arg2:", arg2  
    print "arg3:", arg3  
  
args = ["two", 3] #list  
  
fun_var_args_call(1, *args)  

result：

arg1: 1  
arg2: two  
arg3: 3  

def fun_var_args_call(arg1, arg2, arg3):  
    print "arg1:", arg1  
    print "arg2:", arg2  
    print "arg3:", arg3  
  
kwargs = {"arg3": 3, "arg2": "two"} # dictionary  
  
fun_var_args_call(1, **kwargs)  

result：

arg1: 1  
arg2:"two"  
arg3:3