Python3.8

• 海象运算符:=

nums = list(range(10))
# 作用：把等号右面表达式的值 赋值给 这个符号 前面的变量
if (length := len(nums)) > 50:
    print(length)
else:
    print(length + 1)

• fstring增强

name = 'huahua'
age = 18
print(f'{name=}, {age=}')
# name='huahua', age=18

• 函数增强/和*

def fun(a, b, /, c, d, *, e, f):
    print(f'{a=}, {b=}, {c=}, {d=}, {e=}, {f=}')

Python3.9

• 字典合并

d1 = {'a': 1, 'b': 2}
d2 = {'c': 3, 'd': 4, 'b': 5}
new_d = d1 | d2
print(new_d)
# {'a': 1, 'b': 5, 'c': 3, 'd': 4}

• 字典更新

d1 = {'a': 1, 'b': 2}
d2 = {'c': 3, 'd': 4, 'b': 5}
d1 |= d2
print(d1)
# {'a': 1, 'b': 5, 'c': 3, 'd': 4}

• 字符串方法

s = 'Hello World everyone'
# 删除前缀
s.removeprefix('Hello ')
print(s)
# 删除后缀
s.removesuffix(' everyone')
print(s)

Python3.10

• match、case

status = 100
match status:
    case 400:
        print('11')
    case 500:
        print('22')
    case _:
        print('default')

• 新的类型联合运算符

print(isinstance(9, int | str))
# True

• typing.TypeAlias

from typing import TypeAlias

str_list: TypeAlias = list[str]
L1 = str_list(['1', '2'])
L2 = str_list([1, 2])

#执行静态类型检测器mypy test.py，结果：
#test.py:7: error: List item 0 has incompatible type "int"; expected "str"
#test.py:7: error: List item 1 has incompatible type "int"; expected "str"
#Found 2 errors in 1 file (checked 1 source file)