Python **kwargs 的實測

都必填

都有待入值

```python= def test_func(a1, a2): print(a1) print(a2)

if name == 'main': d = dict() d['a1'] = 1 d['a2'] = 1

test_func(**d)


out put
```bash=
1
2

有值未帶入

```python= def test_func(a1, a2): print(a1) print(a2)

if name == 'main': d = dict() d['a1'] = 1

test_func(**d)


out put
```bash=
Traceback (most recent call last):
  File "xxx/main.py", line 44, in <module>
    test_func(**d)
TypeError: test_func() missing 1 required positional argument: 'a2'

有預設值參數

```python= def test_func(a1, a2=None): print(a1) print(a2)

if name == 'main': d = dict() d['a1'] = 1

test_func(**d)



output
```bash=
1
None

帶入沒有該參數的key & value (unexpected-keyword-arguments)

```python= def test_func(a1, a2=None): print(a1) print(a2)

if name == 'main': d = dict() d['a1'] = 1 d['a2'] = 2 d['a3'] = 3

test_func(**d)



output
```bash=
Traceback (most recent call last):
  File "xxx/main.py", line 46, in <module>
    test_func(**d)
TypeError: test_func() got an unexpected keyword argument 'a3'

解決unexpected-keyword-arguments 的作法

適用於向下相容

```python= def test_func(a1, a2=None,**kwargs): print(a1) print(a2) print(kwargs['a3'])