What are the best practices for using type annotations in Python?

What are the best practices for using type annotations in Python?

Using type annotations improves code readability and helps with static type checking. Here are some best practices:

1. Use Optional for nullable types.
2. Prefer List and Dict from the typing module for collections.
3. Annotate function return types for clarity.
4. Use type aliases for complex types.

Can you give an example of using type annotations in a function?

Sure! Here's a simple example:

from typing import List

def greet_users(names: List[str]) -> None:
    for name in names:
        print(f'Hello, {name}!')

What should I do if I have a complex data structure?

For complex data structures, you can create custom types using TypedDict or dataclasses. This allows you to define clear and structured types.

Are there any tools to help with type checking?

Yes! Tools like mypy and pyright can help you perform static type checking in your Python code, ensuring type safety.