Python3.10 official release! Quick overview of new features

Python 3.10 is officially released. Have you tried it yet?

This paper reference since Python official documentation: Python Release Python 3.10.0 | Python.org

Python3.10.0 was officially released on October 4, 2021, just in time for the National Day holiday. As a coders who did not move during the holidays, I naturally experienced the wave at the first time. Compared with previous releases, this release has the following major changes.

Ps: Want to see better typography? Access: funnysaltyfish. Making. IO / 2021/10/05 /…

New Union Type expression

The use of the new version has simplified the Union Type, instead more concise |

The old version:

from typing import Union
a: Union[int.str] = 1
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New version:

a: str | int = 1
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The two are completely equivalent:

Union[int.str] = =int | str # True
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The changes are similar elsewhere:

# the old version:
# 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)

# the old version:
# typing.List[typing.Union[str, int]]
typing.List[str | int]
list[str | int]

# the old version:
# typing.Dict[str, typing.Union[int, float]]
typing.Dict[str.int | float]
dict[str.int | float]
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This feature is also available for isInstance and IsSubClass

# True
isinstance("FunnySaltyFish".int|str)

# True 
issubclass(str.str|int)
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Zip Select strict mode

Zip adds strict to the optional argument. When True, the two iterable entries passed to zip must be of the same length, otherwise ValueError is raised

Old version (and do not add this parameter), when the two lengths are different, the smaller length shall prevail

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)
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Set strict to True

#...
z = zip(names,numbers,strict=True)
#...D: \ \ projects \ python learn \ Py310 exploration. Pyin <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
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Context manager with parentheses

With can be put in parentheses

with (CtxManager() as example):
    ...

with (
    CtxManager1(),
    CtxManager2()
):
    ...

with (CtxManager1() as example,
      CtxManager2()):
    ...

with (CtxManager1(),
      CtxManager2() as example):
    ...

with (
    CtxManager1() as example1,
    CtxManager2() as example2
):
    ...
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Such as

import pathlib
p = pathlib.Path()
p1 = p/"text1.txt" # content: The content of text 1
p2 = p/"text2.txt" # Content: The content of text 2
with(
    p1.open(encoding="utf-8") as f1,
    p2.open(encoding="utf-8") as f2
):
    print(f1.read(), f2.read(), sep="\n") 
    
    # The contents of text 1
	# The content of text 2
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Explicit type alias

Use TypeAlias to explicitly annotate type aliases to improve readability

The old way:

x = int
def plus_int(a:x,b:x) -> x:
    return a+b
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As you can see, x’s are easy to confuse

New way: Use TypeAlias to indicate that this is an alias

from typing import TypeAlias
x : TypeAlias = int
def plus_int(a:x,b:x) -> x:
    return a+b
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match… A case statement

Yes, switch-case is another language. Python finally provides support for switch-case

Complete syntax see: PEP 634 – Structural Pattern Matching: Specification | Python.org

A few examples:

Basic type matching:

day = 6
match day:
    case 1:
        print("Monday")
    case 6 | 7:
        print("Weekend")
    case _ : 
        print("Other circumstances")
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Subject: This is particularly useful when working with command-line arguments

""" @copyright : [FunnySaltyFish](https://funnysaltyfish.github.io) @date : 2021/10/05 21:08:42 """
command = "save 1.txt"
# try changing command to list/copy 1.txt 2
match command.split(""):
    case ["list"] :print("List files ~")
    case ["save", file_name]:
        print(F "save the file to{file_name}")
    case ["copy",source,target]:
        print(F "copy{source} -> {target}")
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Can also match objects:

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 "This is a student whose ID happens to be 2")
    case Student():
        print(F "This is the student whose ID is{a.id}")
    case Teacher():
        print(F "This is the teacher, named{a.name}")
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You can also match a dictionary:

d = {
    "name" : "Bill".# zhang SAN
    "age" : 18."hobby" : "Reading"
} 
match d:
    case {"name":"Zhang", **args}:
        # ** Collect additional parameters
        print("This is Joe.", args) {'age': 18, 'hobby': 'read '}
    case {"name" : name , "age" : age, "hobby": hobby}:
        print(F "I called{name}This year,{age}Years old, like{hobby}") My name is Li Si. I am 18 years old and like reading
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For more complex uses, see PEP 635 — Structural Pattern Matching: Motivation and Rationale comment and PEP 636 | Python.org – Structural Pattern Matching: Tutorial | Python.org

More friendly error notification

Python now throws more explicit errors when your parentheses and quotes are not closed

str = "Unclosed STR File"D: \ \ projects \ python learn \ Py310 exploration. Py", line 90 str = "Not closedstr
          ^
SyntaxError: unterminated string literal (detected at line 90)
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 arr = [1.2.2.3
    
  File "D: \ \ projects \ python learn \ Py310 exploration. Py." ", line 91
    arr = [1.2.2.3
          ^
SyntaxError: '[' was never closed
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Some other updates:

Distutils was abandoned

Setuptools is recommended

OpenSSL 1.1.1 or later is required

Remove the Py_UNICODE encoding API

WSTR of PyUnicodeObject is deprecated and will be removed later

To the end. Fishing for fish.

Author: FunnySaltyFish homepage: FunnySaltyFish. Making. IO /