celery
Behavior of then() for a resolved promise?
What's the expected behavior for calling then() on a resolved promise? Right now you add callbacks that will never get called.
E.g. using an EagerResult in celery you end up with something like this:
val = 40
result = EagerResult(val)
# Internally result.on_ready is a promise that has already fired, e.g. promise(val) is called.
result.then(callback, errback)
# Neither of these will ever fire.
I'd expect adding a callback to an already resolved promise to call it immediately.
Note that Twisted will immediately run your callbacks if a Deferred already has resolved, so I'm expecting the same behavior here.
(As an aside -- I find it odd you can resolve a promise multiple times...but it doesn't seem to have the same callback chain.)
whats your current thoughts on this?
My thought is that it is confusing that the callbacks never get called, but it is unclear what should happen. This package sadly lacks any documentation of the expected behaviors.
some little addition https://github.com/celery/vine/commit/e8813210b8b493a1cea02da94da3fc5f0bedc28e