On Thu, 23 Nov 2017 14:17:32 +0200
Serhiy Storchaka <storchaka@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

Great, so I open this page and see this code:

results = []
for future in list_of_futures:
    results.append(yield future)

Interesting, why don't they use a comprehension for this and instead need to invent a whole `tornado.gen.multi` function?

--

Ivan