*args与**kwargs用法

Posted 2020-10-11

*args 是用来发送一个非键值对的可变数量的参数列表给一个函数.

def test_var_args(f_arg, *argv):
    print("first normal arg:", f_arg)
    for arg in argv:
        print("another arg through *argv:", arg)

test_var_args(‘yasoob‘, ‘python‘, ‘eggs‘, ‘test‘)

输出——》

first normal arg: yasoob
another arg through *argv: python
another arg through *argv: eggs
another arg through *argv: test

**kwargs 允许你将不定长度的键值对, 作为参数传递给一个函数

def greet_me(**kwargs):
    for key, value in kwargs.items():
        print("{0} == {1}".format(key, value))


>>> greet_me(name="yasoob")
name == yasoob

使用 args 和 *kwargs 来调用函数

def test_args_kwargs(arg1, arg2, arg3):
    print("arg1:", arg1)
    print("arg2:", arg2)
    print("arg3:", arg3)
# 首先使用 *args
>>> args = ("two", 3, 5)
>>> test_args_kwargs(*args)
arg1: two
arg2: 3
arg3: 5

# 现在使用 **kwargs:
>>> kwargs = {"arg3": 3, "arg2": "two", "arg1": 5}
>>> test_args_kwargs(**kwargs)
arg1: 5
arg2: two
arg3: 3

标准参数与*args、**kwargs在使用时的顺序

那么如果你想在函数里同时使用所有这三种参数， 顺序是这样的：

some_func(fargs, *args, **kwargs)