Implement support for async and iterators. #3
Conversation
This change makes the decorator work correctly for async functions, instead of always returning the same coroutine, which can only be awaited once and calls subsequent calls to fail. This also detects returned iterators, evaluates them to completion, and returns the result as a tuple. Prior to this change, an exhausted iterator would be returned.
| self.called = False | ||
| self.return_value: typing.Any = None | ||
| self.func = func | ||
| self.is_asyncgen = inspect.isasyncgenfunction(self.func) | ||
| self.is_async = True if self.is_asyncgen else inspect.iscoroutinefunction(self.func) |
There was a problem hiding this comment.
Maybe a comment about why you chose iscoroutinefunction vs something like isawaitable would be good
once/__init__.py
Outdated
| if self.called: | ||
| return self.return_value | ||
| if self.is_asyncgen: | ||
| self.return_value = tuple([i async for i in func(*args, **kwargs)]) |
There was a problem hiding this comment.
This is a big caveat that needs detailing in the documentation, that the generator result gets converted to a tuple. I think the more correct version, that's also more work, would wrap the generator in a generator that extends the return_value list each time next is called. This is potentially surprising enough to call it a bug that warrants exclusion from this library until it's fully supported.
once/__init__.py
Outdated
| if self.called: | ||
| return self.return_value | ||
| with self.lock: | ||
| if self.called: | ||
| return self.return_value | ||
| self.return_value = func(*args, **kwargs) | ||
| if isinstance(self.return_value, types.GeneratorType): |
There was a problem hiding this comment.
Ditto, this is a deal breaker IMO
Also, better handle sync iterators to be API-compatible with the unwrapped function call by returning an iterator object instead of a tuple object.
|
@mattalbr - I would appreciate help with the generator proxy, especially in async. The sync one at least is API-compatible now, but I disabled async because it was not. |
This change makes the decorator work correctly for async functions, instead of always returning the same coroutine, which can only be awaited once and calls subsequent calls to fail.
This also detects returned iterators, evaluates them to completion, and returns the result as a tuple. Prior to this change, an exhausted iterator would be returned.