> There are other implementations of asyncio than the one in CPython.
> Pulsar and Tornado define their own Task class. The greenio project

I'm not sure if it's possible (or even makes any sense) to integrate 
tasks from other frameworks into asyncio.

greenio simply inherits its task class from asyncio.Task, and will
automatically support concurrent.futures if we support them in
asyncio.

> I'm not opposed to support concurrent.futures.Future object. I don't
> like the idea of starting to add a special case for one module. Others
> may want to do the same for their library.

concurrent.futures is in a unique position -- it's already supported and
integrated in asyncio.  We have executors and they are even used for
DNS lookups.  Supporting concurrent.futures in asyncio.Task seems 
natural to me.

I like Alex's approach -- his idea of '__await__' for concurrent.Future
is very generic, so any other framework can integrate it.  Creating
any kind of registry in asyncio.Task seems a bit unnecessary to me at 
this stage.