[Python-ideas] Are there asynchronous generators?

Nick Coghlan ncoghlan at gmail.com
Fri Jul 3 12:36:34 CEST 2015

On 3 July 2015 at 13:16, Andrew Barnert <abarnert at yahoo.com> wrote:
> The difference between a server and an MDI app is that you usually need hundreds or thousands of connections as opposed to a handful of documents, but the control flow for each is usually more linear, so the wizard-like design is a much more obvious choice.

Ah, thank you - yes, the "stepping through a wizard" case is a good
example, as it hits the same kind multi-step process that causes
problems with network applications.

Simple request-response cases are easy to handle with callbacks:
"event A happens, invoke callback B, which will trigger action C". If
things stop there, you're fine.

Things get messier when they start looking like this: "event A
happens, invoking callback B, which triggers action C after setting up
callback D to wait for event E, which triggers action F after setting
up callback G to wait for event H and finally trigger action I"

This is where coroutines help, as that second case instead becomes:
"event A happens, invoking coroutine B, which triggers action C, then
waits for event E, then triggers action F, then waits for event H,
then triggers the final action I"

Rather than having to create a new callback to handle each new
action-event pair, you can instead have a single coroutine which
triggers an action, and then waits for the corresponding event, and
may do this multiple times before terminating.


Nick Coghlan   |   ncoghlan at gmail.com   |   Brisbane, Australia

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