Asynchronous programming

[Christian Gollwitzer]

Am 11.08.16 um 06:38 schrieb Terry Reedy:
> You might be able to glean something from the succession of files I
> uploaded to
> https://bugs.python.org/issue27546
> Integrate tkinter and asyncio (and async)
>
> I started with just mixing tk and asyncio callbacks.  After some
> struggle with similar question as you ask above, I ended up with more or
> less callback free code using async def and async for. Once I got over
> the hump, I rather like it.

Interesting discussion! Tcl itself acquired coroutines some years ago 
(in 8.6) and people in this community are very excited with async based 
programming.

I'm convinced that it is possible to integrate Tcl's event loop with 
asyncio's loop without regular update polling. This might require a 
patch to Tkinter at the C level. For example, an easy way is to put 
Tcl/Tk in it's own thread. The Tcl event loop can be woken up from a 
different thread by the TclThreadQueueEvent() and TclTheradAlert() API 
calls. Basically, you would spawn a new thread (from the C level), when 
loading Tkinter, which loads Tk and sits in a Tcl event loop ("vwait 
forever"). tk.eval() and tk.call() would be redefined to post events 
using the aforementioned functions. When a Tcl callback arrives, it 
would send an event to asyncio in the main thread - no idea how this 
works, though. In the end, it would also allow to use Tkinter from 
different Python threads, because all calls would be rooted to the one 
instance only.

	Christian