What are the advantages of using Depends for dependency injection in FastAPI?

In FastAPI, Depends is used for dependency injection, which provides several advantages:

• Code reuse: common dependencies (e.g., database connection, authorization check) can be defined and used across different endpoints.
• Cleanliness and readability of code: dependencies are explicitly specified in function parameters, making it easier to understand and maintain.
• Automatic lifecycle management: FastAPI automatically creates and destroys dependency objects if they are defined as generators.
• Integration with Python's type system: allows for autocomplete and type checking.

Example of usage:

from fastapi import Depends, FastAPI

def get_token_header(token: str):
    if token != "secret-token":
        raise HTTPException(status_code=400, detail="Invalid Token")

app = FastAPI()

@app.get("/items/")
async def read_items(token: str = Depends(get_token_header)):
    return [{"item": "Foo"}]