What are some examples of type hints in Python 3.10?

What are some examples of type hints in Python 3.10?

In Python 3.10, type hints help specify the expected data types of function arguments and return values. For example:

def add(a: int, b: int) -> int:
    return a + b

This function specifies that both a and b should be integers, and it returns an integer.

Can you show me more complex examples?

Sure! Here's a more complex example using lists and dictionaries:

from typing import List, Dict

def get_user_info(user_ids: List[int]) -> Dict[int, str]:
    return {user_id: f'User {user_id}' for user_id in user_ids}

This function takes a list of integers and returns a dictionary mapping each user ID to a string.

What about using type hints with classes?

Great question! Here's an example with a class:

class Person:
    def __init__(self, name: str, age: int) -> None:
        self.name = name
        self.age = age

    def greet(self) -> str:
        return f'Hello, my name is {self.name} and I am {self.age} years old.'

This class uses type hints for the constructor and the greet method.

Are there any new features in Python 3.10 related to type hints?

Yes! Python 3.10 introduced the | operator for union types, allowing you to write type hints more concisely. For example:

def handle_data(data: int | str) -> None:
    print(data)

This indicates that data can be either an integer or a string.