关于Python中*args和**kwargs的深入理解

In [6]: a, b, c = [1, 2, 3]
In [7]: a
Out[7]: 1
In [8]: b
Out[8]: 2
In [9]: c
Out[9]: 3

In [10]: a, *other = [1, 2, 3, 4]
In [11]: a
Out[11]: 1
In [12]: other
Out[12]: [2, 3, 4]
 
In [13]: a, *middle, x = [1, 2, 3, 4]
In [14]: middle
Out[14]: [2, 3]

In [15]: print(['a', 'b', 'c', 'd'])
['a', 'b', 'c', 'd']
 
In [16]: print(*['a', 'b', 'c', 'd'])
a b c d

In [1]: def func(a, b, c, d):
   ...:    print(a, b, c, d)

In [2]: func(1, 2, 3, 4)
1 2 3 4

In [3]: func(d=1, c=2, b=3, a=4)
4 3 2 1

In [4]: func(1, 2, d=3, c=4)
1 2 4 3
 
In [5]: func(1, 2, a=3, c=4)
TypeError: func() got multiple values for argument 'a'

In [1]: def func(var, *args, key=None, **kwargs):
   ...:     print('args: ', args)
   ...:     print('kwargs: ', kwargs)

In [2]: func('one', 'two', 'three', key='key', four=4, five=5,)
args:  ('two', 'three')
kwargs:  {'four': 4, 'five': 5}
 
In [3]: func('one', 'two', key='key', three='three', four=4, five=5,)
args:  ('two',)
kwargs:  {'three': 'three', 'four': 4, 'five': 5}

In [1]: def func(a, /, b, *, c, d):
   ...:    print(a, b, c, d)

In [2]: func(1, 2, c=3, d=4)
1 2 3 4
In [3]: func(1, b=2, c=3, d=4)
1 2 3 4
 
In [4]: func(a=1, b=2, c=3, d=4)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: func() got some positional-only arguments passed as keyword arguments: 'a'
 
In [5]: func(1, 2, 3, d=4)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: func() takes 2 positional arguments but 3 positional arguments (and 1 keyword-only argument) were given

In [1]: a = {'k': 1, 'm': 2}
In [2]: y = {'y': '3', 'z': 'ii'}
 
In [3]: {**a}
Out[3]: {'k': 1, 'm': 2}
In [4]: {**a, **y}
Out[4]: {'k': 1, 'm': 2, 'y': '3', 'z': 'ii'}
In [5]: {**a, **y, 'uu': 88}
Out[5]: {'k': 1, 'm': 2, 'y': '3', 'z': 'ii', 'uu': 88}