Migrating to Python 3.10

• Motivation to use match instead of ifs

• Another explicit

• When you created decorator

• Union types as X | Y

Match

If x is tuple

if isinstance(x, tuple) and len(x) == 2:
    host, port = x
    mode = "http"
elif isinstance(x, tuple) and len(x) == 3:
    host, port, mode = x
# Etc.

match x:
    case host, port:
        mode = "http"
    case host, port, mode:
        pass
# Etc.

If x is JSON

{
	"type": "cat",
	"name": "Cat name 1",
	"pattern": "Pattern 1"
}

{
	"type": "dog",
	"name": "Dog name 1",
	"breed": "Breed 1"
}

match json_pet:
    case {"type": "cat", "name": name, "pattern": pattern}:
        return Cat(name, pattern)
    case {"type": "dog", "name": name, "breed": breed}:
        return Dog(name, breed)
    case _:
        raise ValueError("Not a suitable pet")

Parameter typing

from typing import Awaitable, Callable, TypeVar

R = TypeVar("R")

def add_logging(f: Callable[..., R]) -> Callable[..., Awaitable[R]]:
  async def inner(*args: object, **kwargs: object) -> R:
    await log_to_database()
    return f(*args, **kwargs)
  return inner

@add_logging
def takes_int_str(x: int, y: str) -> int:
  return x + 7

await takes_int_str(1, "A")
await takes_int_str("B", 2) # fails at runtime