Some Python Type Challenges

Zettel#176

zettelkasten
Published

2024-09-22

A series of Python type challenges made by laike9m:

https://python-type-challenges.zeabur.app/

Even in the basic challenges, I’ve discovered typing.Final (added in version 3.8) and the deprecated typing.TypeAlias (added in version 3.10 but deprecated since version 3.12) that should be replaced with the type statement.

typing.Final

Final names cannot be reassigned in any scope. Final names declared in class scopes cannot be overridden in subclasses. For example:

from typing import Final


MAX_SIZE: Final = 9000
MAX_SIZE += 1  # Error reported by type checker

class Connection:
    TIMEOUT: Final[int] = 10

class FastConnector(Connection):
    TIMEOUT = 1 # Error reported by type checker

type statement

The type statement declares a type alias, which is an instance of typing.TypeAliasType.

For example, the following statement creates a type alias:

type Point = tuple[float, float]

References