Python 3.11 - Five Cool Features!

Python 3.11 - Five Cool Features!

Sadra Yahyapour's photo
Sadra Yahyapour
·Oct 27, 2022·

2 min read

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Table of contents

  • tomllib Is Added to the Standard Library
  • add_note Method Is Added to Exception Base-Class
  • Tracebacks Are More Detailed
  • Self Type Class Is Here
  • Use StrEnum Over Enum For Your Strings
  • Final Words

This is a quick walk-through of the newly added features in Python 3.11. Of course, you can find many more other features and improvements during the migration from 3.10 to 3.11 but I tried to note five handy features and improvements that I think would be perfect for you to observe while coding along in Python.

tomllib Is Added to the Standard Library

The tomllib library used to be a third-party package for your Python<3.11 projects. Now, they've decided to add this handy package to the official standard library so that you won't need any further installation to access the utilities this library provides for you.

import tomllib

with open('setup.toml', 'rb') as f:
    data = tomllib.load(f)
    print(data) # -> {...}

TOML stands for Tom's Obvious, Minimal Language. It's a powerful config file data type that is compatible with other Python components such as setuptools. It's also more human-readable compared to JSON, YAML, and some other structures.

add_note Method Is Added to Exception Base-Class

try:
    email, message = input('to: '), input('message: ')
    send_email(email, message)
except ConnectionError as e:
    e.add_note('Make sure the mail server is up and running')
    raise

Tracebacks Are More Detailed

It shows the exact place that caused the error with "~" followed by "^".

Traceback (most recent call last):
    File "query.py", line 32, in query_user
        return 1 + query_count(db, response[e][b][user, retry=True)
                                   ~~~~~~~~~~~~~~~^^^^
TypeError: NoneType object is not subscriptable

Self Type Class Is Here

For all the methods you have, you can annotate the args with Self other than the name of your class. It helps you in a case when you have multiple methods that have arguments annotated to the class and you decide to change the class name. (There is a difference between self and Self in Python from now on. self refers to the object whereas Self refers to the class for annotations)

class Student:
    @classmethod
    def give_info(cls) -> Self:
        ...

Use StrEnum Over Enum For Your Strings

If you need a class of strings, then use StrEnum. They make your code readable and you won't need any additional writing. Just use auto() for the values. Both following enums work as same as the other.

from enum import Enum, StrEnum, auto

class Colors(Enum):
    RED = 'red'
    BLUE = 'blue'
    WHITE = 'white'

class Colors(StrEnum):
    RED = auto()
    BLUE = auto()
    WHITE = auto()

We also have ReprEnum which changes the return value of __repr__ of each object.

Final Words

We have so many typing improvements in 3.11 so far. That's awesome! Now all our annotations are more accurate and detailed.

 
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