Reassignments to returned cancellables from within async blocks

[tcard]

At some points, we're doing the equivalent of this (pseudo-Swift):

func doSomething(callback) -> ARTCancellable {
    let task = someAsyncSubOperation() {
        task = innerAsyncOperation() {
            callback(...)
        }
    }
    return task
}

This won't work as expected. The inner assignment to task won't have any effect, since at that point we will have returned the previous task already.

What we need to do is to propagate a cancel to the top-level task to subtasks somehow. I don't know if there's some way of doing this or we'll have to implement it ourselves.

┆Issue is synchronized with this Jira Bug by Unito

[ricardopereira]

Oh, you're right. I think we have something like that in the Auth request. It's changing the local variable only. Well, we can use pointer to pointer and change the outside one but we need to be careful to not create leaks over the codebase.

[ricardopereira]

Maybe the best is to use some promise library. WDYT?