[Python-Dev] async/await in Python; v2

[Greg Ewing]

Yury Selivanov wrote:

> So you would have to write 'await fut()'?  This is non-intuitive.

That's because PEP 492 and its terminology encourage you
to think of 'await f()' as a two-step process: evaluate f(),
and then wait for the thing it returns to produce a
result.

PEP 3152 has a different philosophy. There, 'cocall f()'
is a one-step process: call f and get back a result (while
being prepared to get suspended in the meantime).

The two-step approach has the advantage that you can
get hold of the intermediate object and manipulate it.
But I don't see much utility in being able to do that.

Keep in mind that you can treat cofunctions themselves
as objects to be manipulated, just like you can with
ordinary functions, and all the usual techniques such
as closures, * and ** parameters, etc. are available
if you want to encapsulate one with some arguments.

About the only thing you gain from being able to pass
generator-iterators around instead of the functions that
produce them is that you get to write

    t = Task(func(args))

instead of

    t = Task(func, args)

which seems like a very minor thing to me. I would even
argue that the latter is clearer, because it makes it
very obvious that the body of func is *not* executed
before the Task is constructed. The former makes it
look as though the *result* of executing func with
args is being passed to Task, rather than func itself.

-- 
Greg