await — Advanced Playground

Pauses execution of an async coroutine until a result is available

Python Playground

import asyncio

class AsyncResult:
    def __init__(self, value, delay=0):
        self.value = value
        self.delay = delay

    def __await__(self):
        # Must return an iterator
        if self.delay:
            yield from asyncio.sleep(self.delay).__await__()
        return self.value

async def main():
    result = await AsyncResult(42, 0.01)
    print(f"Got: {result}")

    # Chain awaitables
    a = await AsyncResult(10)
    b = await AsyncResult(20)
    print(f"Sum: {a + b}")

asyncio.run(main())

# Check what's awaitable
print(f"\ncoroutine awaitable: {hasattr(main, '__await__') or asyncio.iscoroutinefunction(main)}")

Output

Click "Run" to execute your code

Any object with __await__ can be used with 'await'. __await__ must return an iterator. Coroutines, Tasks, and Futures all implement this protocol.

Challenge

Try modifying the code above to explore different behaviors. Can you extend the example to handle a new use case?

View all Advanced examples for await