What are some examples of annotations in Python 3.10?

What are some examples of annotations in Python 3.10?

In Python 3.10, annotations can be used to indicate the expected types of function arguments and return values. For example:

def greet(name: str) -> str:
    return f'Hello, {name}!'

This function uses annotations to specify that name should be a string and the function returns a string.

Can you show me more complex examples?

Sure! Here's a more complex example using a list of integers:

def process_numbers(numbers: list[int]) -> float:
    return sum(numbers) / len(numbers) if numbers else 0.0

This function takes a list of integers and returns their average.

What about using annotations with classes?

Absolutely! Here's an example with a class:

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

In this class, the constructor uses annotations to specify that name is a string and age is an integer.

Are there any new features in Python 3.10 related to annotations?

Yes! Python 3.10 introduced the | operator for union types, allowing you to write annotations like this:

def handle_data(data: str | None) -> None:
    pass

This indicates that data can be either a string or None.