parent of chained task returning tuple

[komuw]

Currently, if we have a chained task, we use the return_value of the parent to queue the child:

wiji/wiji/worker.py

Lines 183 to 186 in e9da8ef

	return_value = await self.the_task.run(*task_args, **task_kwargs)
	if self.the_task.chain:
	# enqueue the chained task using the return_value
	await self.the_task.chain.delay(return_value)

However, what happens if return_value is a tuple?
I think in that case, we ought to;

await self.the_task.chain.delay(*return_value)

ie only if return_value is a tuple

[komuw]

def cool():
    return 34, "name"

def run(*args, **kwargs):
    print(args, kwargs)

return_value = cool()

## what we are currently doing
>>> run(return_value)
((34, 'name'),) {}

## versus what I think we ought to do
>>> run(*return_value)
(34, 'name') {}
>>>

[komuw]

however, think of situation where:

import typing
def run(value: typing.Tuple, **kwargs):
    print(value, kwargs)

ie, run expects a tuple as it's first argument.

in such a case

## what we are currently doing
>>> run(return_value)
(34, 'name') {}

## versus what I think we ought to do
>>> run(*return_value)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: run() takes 1 positional argument but 2 were given

so we haven't made the situation any better.

[komuw]

this is the way celery does it; https://github.com/celery/celery/blob/e2161783e1a4cb021cd37d5df8581f7729f9095c/celery/app/trace.py#L439-L446

[komuw]

I think, we'll leave it as is for now.

[komuw]

I'm labelling this as a bug since it might be surprising for people using wiji.