python/*args和**kwargs

*args和**kwargs

#coding=utf8
__author__ = 'Administrator'
# 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('args:', farg)
    print(args)
    print(*args)
    for value in args:
        print('another arg:',value)
# *args可以当作可容纳多个变量组成的list或tuple
fun_var_args(1, 'two', 3, None)
#args: 1
#another arg: two
#another arg: 3
#another arg: None
 
 
def fun_var_kwargs(farg, **kwargs):
    print('args:', farg)
    # print(**kwargs) #直接报错
    print(kwargs)
    for key in kwargs:
        print('another keyword arg:%s:%s' % (key, kwargs[key]))
# myarg1,myarg2和myarg3被视为key， 感觉**kwargs可以当作容纳多个key和value的dictionary
fun_var_kwargs(1, myarg1='two', myarg2=3, myarg3=None)
# 输出：
#args: 1
#another keyword arg:myarg1:two
#another keyword arg:myarg2:3
#another keyword arg:myarg3:None
 
 
def fun_args(arg1, arg2, arg3):
    print ('arg1:', arg1)
    print ('arg2:', arg2)
    print ('arg3:', arg3)
myargs = ['1', 'two', None]     # 定义列表
fun_args(*myargs)
# 输出：
#arg1: 1
#arg2: two
#arg3: None
mykwargs = {'arg1': '1', 'arg2': 'two', 'arg3': None}      # 定义字典类型
fun_args(**mykwargs)
# 输出：
#arg1: 1
#arg2: two
#arg3: None
# 两者都有<br><br>
def fun_args_kwargs(*args, **kwargs):
    print ('args:', args)
    print ('kwargs:', kwargs)
args = [1, 2, 3, 4]
kwargs = {'name': 'BeginMan', 'age': 22}
fun_args_kwargs(args,kwargs)
# args: ([1, 2, 3, 4], {'age': 22, 'name': 'BeginMan'})
# kwargs: {}
fun_args_kwargs(1,2,3,a=100)
#args: (1, 2, 3)
#kwargs: {'a': 100}
fun_args_kwargs(*(1,2,3,4),**{'a':None})
#args: (1, 2, 3, 4)
#kwargs: {'a': None}