I'm looking for a clean method to manage a batch of async calls where the number varies. For instance, if I have a condition in a function that decides whether to perform an extra database lookup based on a boolean flag, how should I handle that? In my current code, I use `asyncio.gather()` to collect results, but I use `asyncio.sleep(0, True)` for cases where an async call isn't needed, which feels a bit off. I'm wondering if there's a cleaner or more straightforward solution instead of using sleep for this purpose.
2 Answers
Check out using `asyncio.TaskGroup()` if you're working with Python 3.11 or newer. It gives a clearer structure for managing tasks. You can create tasks for the email retrieval and handle exceptions better without losing track of others that might fail. Here's a snippet to illustrate:
```python
async with asyncio.TaskGroup() as tg:
emails_task = tg.create_task(self._get_emails_for_notifications())
confirmed_task = None
if exclude_unconfirmed_email:
confirmed_task = tg.create_task(self._get_notification_email_confirmed())
if not (emails := emails_task.result()):
raise ...
if confirmed_task and not confirmed_task.result():
raise ...
return emails[0]
```
This way, you don’t need to fall back on sleep, and the semantics of the code are clearer.
If you prefer not to use blocking tasks or sleep, consider using `asyncio.Future`. You can create an awaitable that returns a preset value instead. Here's how you can do it:
```python
def _future[T](value: T) -> asyncio.Future[T]:
fut = asyncio.Future()
fut.set_result(value)
return fut
```
You could swap out your sleep call with this future, providing a result when you need one without the extra weirdness of sleep.
That's a neat solution! The wrapper approach helps but then it just becomes another thing to remember instead of the sleep. It makes me wonder what benefits it brings compared to using `sleep(0)` directly.
But using `sleep` to yield to the event loop can be confusing, especially if you're coming from a different programming background. It’s not the most intuitive idea! I totally get that concern! I agree that TaskGroup adds a bit of complexity with the extra checks, but it also brings safety and clarity when handling failures.