What’s New In Python 3.10

from typing import Callable, ParamSpec, TypeVar

P = ParamSpec('P')
R = TypeVar('R')

def decorator(func: Callable[P, R]) -> Callable[P, R]:
    def wrapper(*args: P.args, **kwargs: P.kwargs) -> R:
        print(f"Calling {func} with args={args} and kwargs={kwargs}")
        return func(*args, **kwargs)
    return wrapper

from collections.abc import Callable
from threading import Lock
from typing import Concatenate, ParamSpec, TypeVar

P = ParamSpec('P')
R = TypeVar('R')

my_lock = Lock()

def with_lock(f: Callable[Concatenate[Lock, P], R]) -> Callable[P, R]:
    def inner(*args: P.args, **kwargs: P.kwargs) -> R:
        return f(my_lock,*args,**kwargs)
    return inner

@with_lock
def sum_threadsafe(lock: Lock, numbers: list[float]) -> float:
    with lock:
        return sum(numbers)

sum_threadsafe([1.1, 2.2, 3.3])

from typing import TypeAlias

Vector: TypeAlias = list[int]

from typing import TypeGuard

def is_str_list(val: list[object]) -> TypeGuard[list[str]]:
    return all(isinstance(x, str) for x in val)

x: list[object] = ["a", "b", "c"]
if is_str_list(x):
    print("All strings:", x)
else:
    print("Not all strings")

match subject:
    case <pattern_1>:
        <action_1>
    case <pattern_2>:
        <action_2>
    case <pattern_3>:
        <action_3>
    case _:
        <action_wildcard>

def http_error(status):
    match status:
        case 400:
            return "Bad request"
        case 404:
            return "Not found"
        case 418:
            return "I'm a teapot"
        case _:
            return "Something's wrong with the internet"

# point is an (x, y) tuple
match point:
    case (0, 0):
        print("Origin")
    case (0, y):
        print(f"Y={y}")
    case (x, 0):
        print(f"X={x}")
    case (x, y):
        print(f"X={x}, Y={y}")
    case _:
        raise ValueError("Not a point")

class Point:
    def __init__(self, x, y):
        self.x = x
        self.y = y

def location(point):
    match point:
        case Point(x=0, y=0):
            print("Origin is the point's location.")
        case Point(x=0, y=y):
            print(f"Y={y} and the point is on the y-axis.")
        case Point(x=x, y=0):
            print(f"X={x} and the point is on the x-axis.")
        case Point():
            print("The point is located somewhere else on the plane.")
        case _:
            print("Not a point")

class Point:
    __match_args__ = ('x', 'y')

    def __init__(self, x, y):
        self.x = x
        self.y = y

def location(point):
    match point:
        case Point(0, 0):
            print("Origin is the point's location.")
        case Point(0, y=y):
            print(f"Y={y} and the point is on the y-axis.")
        case Point(x=x, y=y):
            print(f"X={x} and Y={y}.")
        case Point():
            print("The point is located somewhere else on the plane.")
        case _:
            print("Not a point")

location(Point(0,0))
location(Point(0,1))
location(Point(1,1))

match points:
    case []:
        print("No points in the list.")
    case [Point(0, 0)]:
        print("The origin is the only point in the list.")
    case [Point(x, y)]:
        print(f"A single point {x}, {y} is in the list.")
    case [Point(0, y1), Point(0, y2)]:
        print(f"Two points on the Y axis at {y1}, {y2} are in the list.")
    case _:
        print("Something else is found in the list.")

match test_variable:
    case ('warning', code, 40):
        print("A warning has been received.")
    case ('error', code, _):
        print(f"An error {code} occurred.")

match point:
    case Point(x, y) if x == y:
        print(f"The point is located on the diagonal Y=X at {x}.")
    case Point(x, y):
        print(f"Point is not on the diagonal.")

File "example.py", line 3
    some_other_code = foo()
                    ^
SyntaxError: invalid syntax

File "example.py", line 1
    expected = {9: 1, 18: 2, 19: 2, 27: 3, 28: 3, 29: 3, 36: 4, 37: 4,
               ^
SyntaxError: '{' was never closed

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