[Python-Dev] Tricky way of of creating a generator via a comprehension expression

[Antoine Pitrou]

On Thu, 23 Nov 2017 14:17:32 +0200
Serhiy Storchaka <storchaka at gmail.com> wrote:
> 
> I used the "yield" statement, but I never used the "yield" expressions. 
> And I can't found examples. Could you please present a real-world use 
> case for the "yield" (not "yield from") expression?

Of course I can.  "yield" expressions are important for writing
Python 2-compatible asynchronous code while avoiding callback hell:

See e.g. http://www.tornadoweb.org/en/stable/gen.html
or https://jdb.github.io/concurrent/smartpython.html

There are tons of real-world code written using this scheme (as opposed
to almost no real-world code, even Python 2-only, using "yield" in
comprehensions or generation expressions).

Regards

Antoine.