All 15 Async Generators & Async Context Managers questions
More in Async Generators & Async Context Managers
How would you implement a custom async iterator class from scratch, without using an async generator function? How do you handle backpressure when an async generator produces items faster than the consumer can process them? How would you implement timeout handling for an async generator's individual yields, so a stalled source doesn't hang the consumer forever? How do async generators interact with asyncio.Queue to implement a producer-consumer pattern across separate tasks? How do you properly propagate cancellation into an async generator when the consuming task is cancelled mid-iteration? How would you implement a 'fan-out, fan-in' pattern using multiple async generators consumed concurrently and merged into one stream? How do you correctly test async generators and async context managers using pytest and pytest-asyncio?
Advertisement
Python › Async Generators & Async Context Managers

How would you implement an async context manager that also supports being used as a decorator, similar to contextlib.contextmanager's decorator support?

Advanced

Answer

contextlib.AsyncContextDecorator (or simply using @asynccontextmanager, which already supports this) lets the same async context manager be applied either with 'async with' OR as a decorator on an async function, automatically wrapping the entire function call in the context manager's enter/exit logic.
from contextlib import asynccontextmanager

@asynccontextmanager
async def timed():
    start = time.monotonic()
    try:
        yield
    finally:
        print(f"Took {time.monotonic() - start:.2f}s")

@timed()
async def slow_operation():
    await asyncio.sleep(1)
Real-world example Building a reusable async timing or logging decorator that can ALSO be used explicitly as an 'async with' block when needed.

Common follow-ups: What's the underlying mechanism that lets a single @asynccontextmanager-decorated function support both usages?

Decorators
All 15 Async Generators & Async Context Managers questions