Class-based task definitions

[piercefreeman]

Class-based task definitions

[AlecRosenbaum]

In order to pass the function to the worker, we need to be able to serialize a dotted path to the task, which is then used to import and run the task on the worker side.

If you define tasks like this, my_task.__name__ == 'MyTask', so the worker ends up running module.MyTask(*args, **kwargs). I'm not aware of a way to programmatically generate a dotted path to a callable global variable, which is essentially what my_task is in this example. I have a feeling it's not possible to do from the object-definition side because you could end up with ambiguous scenarios when you have multiple references to the same object. It might be possible if you try to get a stack trace and inspect it looking for an assignment, but that would be really messy and unreliable.

There's a pretty nasty way to work around it that I wouldn't recommend, which would be setting __name__ after init to match the global name:

task = MyTask(echo=3)
task.__name__ = 'my_task'
my_task = tiger.task(task)

I'm sure your real scenario is more complicated, but in this example (assuming I couldn't change MyTask) I'd probably write something like this:

@tiger.task
def my_task(*args, **kwargs):
	return MyTask(echo=3)(*args, **kwargs)

[AlecRosenbaum]

In short, I don't foresee us adding support for this type of usage primarily because I'm not aware of a reliable way to get an importable path to the task when they're defined like this.

For now I'm going to close the issue but feel free to reopen if there's a good way to solve the problem I posed above that I'm just not aware of. Alternatively if you can provide more details on the real use case that invalidates my approach above, I'll try to respond to any additional comments when I get a chance.