Python - 3.8 新特性之仅位置参数 & 仅关键字参数

def test1(a, b, c):
    print(a, b, c)


test1(a=1, b=2, c=3)


def test(a, /, b, c):
    print(a, b, c)


# 正确
test(1, b=2, c=3)
test(*(1,), b=2, c=3)

# 错误
test(a=1, b=2, c=3)


1 2 3
1 2 3
1 2 3

    test(a=1, b=2, c=3)
TypeError: test() got some positional-only arguments passed as keyword arguments: ‘a‘

def f1(a, *, b, c):
    return a + b + c


# 正确
f1(1, b=2, c=3)
f1(1, **{"b": 2, "c": 3})

# 错误
f1(1, 2, c=3)


# 输出结果
6
6

    f1(1, 2, c=3)
TypeError: f1() takes 1 positional argument but 2 positional arguments (and 1 keyword-only argument) were given 

def f(a, /, b, *, c):
    print(a, b, c)


# 正确
f(1, 2, c=3)
f(1, b=2, c=3)

# 错误
f(a=1, b=2, c=3)
f(1, 2, 3)


# 输出结果
1 2 3
1 2 3

def f(a, b, /, c, *, d, e):
    print(a, b, c, d, e)


# 正确
f(1, 2, c=3, d=4, e=5)

# 错误
f(1, 2, 3, 4, 5)

# 输出结果
1 2 3 4 5