[Python-Dev] PEP 492: async/await in Python; version 5

[Guido van Rossum]

For this you should probably use an integration of asyncio (which can do
async subprocess output nicely) with Tkinter. Over in tulip-land there is
an demo of such an integration.

On Tue, May 5, 2015 at 6:03 PM, Terry Reedy <tjreedy at udel.edu> wrote:

> On 5/5/2015 6:25 PM, Yury Selivanov wrote:
>
>  Yes, there is no other popular event loop for 3.4 other
>> than asyncio,
>>
>
> There is the tk(inter) event loop which also ships with CPython, and which
> is commonly used.
>
>  that uses coroutines based on generators
>>
>
> Oh ;-) Tkinter event loop is callback based.  AFAIK, so is the asyncio
> event loop, but that is somehow masked by tasks that interface to
> coroutines.  Do you think the 'somehow' could be adapted to work with the
> tkinter loop?
>
> What I do not understand is how io events become event loop Event
> instances.  For tk, keyboard and mouse actions seen by the OS become tk
> Events associated with a widget.  Some widgets generate events. User code
> can also generate (pseudo)events.
>
> My specific use case is to be able to run a program in a separate process,
> but display the output in the gui process -- something like this (in Idle,
> for instance).  (Apologies if this misuses the new keywords.)
>
> async def menu_handler()
>     ow = OutputWindow(args)  # tk Widget
>     proc = subprocess.Popen (or multiprocessing equivalent)
>     out = (stdout from process)
>     await for line in out:
>         ow.write(line)
>     finish()
>
> I want the handler to not block event processing, and disappear after
> finishing.  Might 492 make this possible someday?  Or would having 'line in
> pipe' or just 'data in pipe' translated to a tk event likely require a
> patch to tk?
>
> --
> Terry Jan Reedy
>
>
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-- 
--Guido van Rossum (python.org/~guido)
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