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重磅来袭!Python3.10正式版发布了!我还在用3.6

2022-10-09 18:06:34 3408

摘要:来源:juejin.cn/post/7015590447745613854Python 3.10正式发布,你尝鲜了吗?本文参考自 Python官方文档 :Python Release Python 3.10.0 | Python.org[1...

来源:
juejin.cn/post/7015590447745613854

Python 3.10正式发布,你尝鲜了吗?

本文参考自 Python官方文档 :Python Release Python 3.10.0 | Python.org[1]

在正值国庆假期人山人海的2021年10月4号,Python官方正式发布了Python3.10.0[2]。作为一只假期期间宅着不动的coding人,自然是第一时间体验了一波。相较于之前的版本,该版本有以下主要变更。

新的 Union Type表达

新版本简化了 Union Type 的使用 ,改为更为简洁的|

旧版:

from typing import Union
a: Union[int, str] = 1

新的版本:

a: str | int = 1

二者完全等价:

Union[int, str] == int | str # True

这类变化在其他地方也相似:

# 旧版:
# def f(list: List[Union[int, str]], param: Optional[int]) -> Union[float, str]
def f(list: List[int | str], param: int | None) -> float | str:
pass
f([1, "abc"], None)
# 旧版:
# typing.List[typing.Union[str, int]]
typing.List[str | int]
list[str | int]
# 旧版:
# typing.Dict[str, typing.Union[int, float]]
typing.Dict[str, int | float]
dict[str, int | float]

该特性也可用于 isinstanceissubclass

# True
isinstance("FunnySaltyFish", int|str)
# True
issubclass(str, str|int)

zip 可选严格模式

zip新增可选参数strict, 当该选项为True时,传入zip的两个可迭代项长度必须相等,否则将抛出ValueError

旧版(及不加此参数),当二者长度不等时,以长度较小的为准

names = ["a","b","c","d"]
numbers = [1,2,3]
z = zip(names,numbers)
for each in z:
print(each)
# ("a", 1)
# ("b", 2)
# ("c", 3)

设置strict为True

# ...
z = zip(names,numbers,strict=True)
# ...
d:projectspythonlearnPy310探索.py in <module>
3 numbers = [1,2,3]
4 z = zip(names,numbers,strict=True)
----> 5 for each in z:
6 print(each)
ValueError: zip argument 2 is shorter than argument 1

带括号的上下文管理器

with可以加括号了

with (CtxManager as example):
...
with (
CtxManager1,
CtxManager2
):
...
with (CtxManager1 as example,
CtxManager2):
...
with (CtxManager1,
CtxManager2 as example):
...
with (
CtxManager1 as example1,
CtxManager2 as example2
):
...

import pathlib
p = pathlib.Path
p1 = p/"text1.txt" # 内容:文本1的内容
p2 = p/"text2.txt" # 内容:文本2的内容
with(
p1.open(encoding="utf-8") as f1,
p2.open(encoding="utf-8") as f2
):
print(f1.read, f2.read, sep=" ")
# 文本1的内容
# 文本2的内容

显式类型别名

使用 TypeAlias 显式标注类型别名,提高可读性

旧的方式:

x = int
def plus_int(a:x,b:x) -> x:
return a+b

可以看到,x很容易被搞混

新的方式:使用 TypeAlias表明这是个别名

from typing import TypeAlias
x : TypeAlias = int
def plus_int(a:x,b:x) -> x:
return a+b

match...case语句

对,就是其他语言的switch-case,python终于提供了支持,还是加强版的

完整语法参见:PEP 634 -- Structural Pattern Matching: Specification | Python.org[3]

举几个例子:

基本的类型匹配:

day = 6
match day:
case 1:
print("星期一")
case 6 | 7:
print("周末")
case _ :
print("其他情况")

subject:这在处理命令行参数的时候特别有用

"""
@copyright : [FunnySaltyFish](https://funnysaltyfish.github.io)
@date : 2021/10/05 21:08:42
"""
command = "save 1.txt"
# 试着把command改成 list / copy 1.txt 2.txt 看看效果
match command.split(" "):
case ["list"]:
print("列出文件~")
case ["save", file_name]:
print(f"保存文件到 {file_name}")
case ["copy",source,target]:
print(f"拷贝 {source} -> {target}")

也可以匹配对象:

class Person:
pass
class Student(Person):
def __init__(self, id: int) -> None:
self.id = id
class Teacher(Person):
def __init__(self, name: str) -> None:
self.name = name
a = Student(1)
# a = Student(2)
# a = Teacher("FunnySaltyFish")
match a:
case Student(id = 2):
print(f"这是位学生,且id正好是2")
case Student:
print(f"这是学生,id为{a.id}")
case Teacher:
print(f"这是老师, 姓名为{a.name}")

当然也可以匹配字典:

d = {
"name" : "李四", # 张三
"age" : 18,
"hobby" : "阅读"
}
match d:
case {"name":"张三", **args}:
# **收集其他参数
print("这是张三", args) # 这是张三 {"age": 18, "hobby": "阅读"}
case {"name" : name , "age" : age, "hobby": hobby}:
print(f"我叫{name}, 今年{age}岁, 喜欢{hobby}") #我叫李四,今年18岁,喜欢阅读

更复杂的还有结合Guard、匹配捕获等使用,具体可以参见:PEP 635 -- Structural Pattern Matching: Motivation and Rationale | Python.org[4]和 PEP 636 -- Structural Pattern Matching: Tutorial | Python.org[5]

更友好的报错提示

现在,当你的括号、引号未闭合时,python会抛出更加清晰明了的错误

str = "未闭合的str
File "d:projectspythonlearnPy310探索.py", line 90
str = "未闭合的str
^
SyntaxError: unterminated string literal (detected at line 90)
 arr = [1, 2, 2, 3
File "d:projectspythonlearnPy310探索.py", line 91
arr = [1, 2, 2, 3
^
SyntaxError: "[" was never closed

其他一些更新:

distutils 被弃用

推荐使用 setuptools

需要 OpenSSL 1.1.1 及以上版本

移除 Py_UNICODE编码API

PyUnicodeObject的wstr被弃用,并将在之后移除

完。摸鱼去了。

参考资料

[1]

https://www.python.org/downloads/release/python-3100/: https://link.juejin.cn?target=https%3A%2F%2Fwww.python.org%2Fdownloads%2Frelease%2Fpython-3100%2F

[2]

https://www.python.org/downloads/release/python-3100/: https://link.juejin.cn?target=https%3A%2F%2Fwww.python.org%2Fdownloads%2Frelease%2Fpython-3100%2F

[3]

https://www.python.org/dev/peps/pep-0634/#id25: https://link.juejin.cn?target=https%3A%2F%2Fwww.python.org%2Fdev%2Fpeps%2Fpep-0634%2F%23id25

[4]

https://www.python.org/dev/peps/pep-0635/#id15: https://link.juejin.cn?target=https%3A%2F%2Fwww.python.org%2Fdev%2Fpeps%2Fpep-0635%2F%23id15

[5]

https://www.python.org/dev/peps/pep-0636/: https://link.juejin.cn?target=https%3A%2F%2Fwww.python.org%2Fdev%2Fpeps%2Fpep-0636%2F

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