Asynchronous programming

[Terry Reedy]

On 8/10/2016 11:53 PM, Steven D'Aprano wrote:
> The latest versions of Python are introducing new keywords for
> asynchronous programming, async and await. See PEP 492:
>
> https://www.python.org/dev/peps/pep-0492/
>
> Is there a good beginner's tutorial introducing the basics of
> asynchronous programming? Starting with, why and where would you use
> it?
>
> I've read "What colour is your function" and it isn't quite jelling
> for me.
>
> http://journal.stuffwithstuff.com/2015/02/01/what-color-is-your-function/
>
>
>
> How is this the same as, or different from, event-based programming?
> I'm familiar with programming in an event-based language where the
> interpreter itself provides an event loop and dispatches messages to
> your objects:
>
> - I define objects such as buttons, text fields, etc., and give them
> methods ("handlers") which handle certain messages such as "mouseUp",
> etc.;
>
> - the interpreter runs in a loop, firing off messages in response to
> the user's actions;
>
> - there's a message passing hierarchy, whereby messages are first
> received by (let's say) the button the user clicked on, if not
> handled by a mouseUp method it is passed on to the next object in the
> hierarchy (say, the window), and then finally to the interpreter
> itself, at which point it either ignores the message or raises an
> exception.
>
> If I'm using async and await in Python, where's the event loop? What
> are the messages, and where are they sent? Or am I on the wrong track
> altogether?

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.

-- 
Terry Jan Reedy