there doesn't seem to be a cancelation hook when b...

# coroutines

[jw]

there doesn't seem to be a cancelation hook when building a Deferred (via CompletableDeferred). Is there something else that offers this callback?

[elizarov]

invokeOnCompletion is there. Or what else are you looking for?

[jw]

I'm wrapping Retrofit's Call. It completes with a result or completes exceptionally. I want to propagate cancellation of the Deferred up into the Call though.

[elizarov]

Use invokeOnCompletion and cancel call from there. It should work assuming that cancelling an otherwise completed call has no effect.

[jw]

It's meant to be cheap.

[elizarov]

You can also extend JobSupport just like CompletableDeferred. In this case, onCancellation can be overriden. Less stable API, but less overhead.

[jw]

Can you clarify what you mean by less stable? I thought binary compatibility was guaranteed despite the experimental status.

[jw]

Ah, I think I see it. There are warnings that it is an unstable API.