【python学习笔记】Python中*args 和**kwargs的用法

说明

缺省参数

def foo(a,b=8):
print a,b

foo("leason")  #leason 0
foo("leason",88)  #def 88

参数名传参数

def foo(a,b):
print a,b

foo("hello",'world') # helloworld
foo(b='world',a="hello")   # helloworld

可变长度参数

def foo(arg1,*tupleArg,**dictArg):
print "arg1=",arg1          #arg1=leason
print "tupleArg=",tupleArg  #()
print "dictArg=",dictArg    #[]
foo("leason")

可变长度参数*args

# 接收不定长参数*args
def fun_var_args(farg, *args):
print "arg:", farg
for value in args:
print "another arg:", value

fun_var_args(1, 2, 3) # *args可以当作可容纳多个变量组成的list

<< arg: 1
<< another arg: 2
<< another arg: 3

# 传收不定长参数*args
def fun_var_args_call(arg1, arg2, arg3):
print "arg1:", arg1
print "arg2:", arg2
print "arg3:", arg3

args = [2, 3] #list

fun_var_args_call(1, *args)

<< arg1: 1
<< arg2: 2
<< arg3: 3

可变长度**kwargs

# 接收不定长参数**kwargs
def fun_var_kwargs(arg1, **kwargs):
print "arg1:", arg1
for key in kwargs:
print "%s: %s" % (key, kwargs[key])

fun_var_kwargs(arg1=1, arg2=2, arg3=3) # **kwargs可以当作容纳多个key和value的dict
<< arg1: 1
<< arg2: 2
<< arg3: 3

# 传收不定长参数**kwargs
def fun_var_args_call(arg1, arg2, arg3):
print "arg1:", arg1
print "arg2:", arg2
print "arg3:", arg3

kwargs = {"arg3": 3, "arg2": 2} # dictionary

fun_var_args_call(1, **kwargs)

<< arg1: 1
<< arg2: 2
<< arg3: 3