Thanks, Yury, for you quick response.
On 24.06.2015 22:16, Yury Selivanov
wrote:
Sven,
if we don't have 'async def', and instead say that "a function is
a *coroutine function* when it has at least one 'await'
expression", then when you refactor "useful()" by removing the
"await" from it, it stops being a *coroutine function*, which
means that it won't return an *awaitable* anymore. Hence the
"await useful()" call in the "important()" function will be
broken.
I feared you would say that. Your reasoning assumes that await
needs an explicitly declared awaitable.
Let us assume for a moment, we had no async keyword. So, any
awaitable needs to have at least 1 await in it. Why can we not have
awaitables with 0 awaits in them?
'async def' guarantees that function always return a "coroutine";
it eliminates the need of using @asyncio.coroutine decorator (or
similar), which besides making code easier to read, also improves
the performance. Not to mention new 'async for' and 'async with'
statements.
Recently, I read Guido's blog about the history of Python and how he
eliminated special cases from Python step by step. As I see it, the
same could be done here.
What is the difference of a function (no awaits) or an awaitable
(> 1 awaits) from an end-user's perspective (i.e. the
programmer)?
My answer would be: none. When used the same way, they should behave
in the same manner. As long as, we get our nice tracebacks when
something went wrong, everything seems find to me.
Please, correct me if I am wrong.
This is also covered in the rationale section of the PEP [2]
[1]
https://www.python.org/dev/peps/pep-0492/#importance-of-async-keyword
[2] https://www.python.org/dev/peps/pep-0492/#rationale-and-goals
Thanks,
Yury
P.S. This and many other things were discussed at length on the
mailing lists, I suggest you to browse through the archives.
I can imagine that. As said I went through of some of them, but it
could be that I missed some of them as well.
Is there a way to search them through (by not using Google)?
Regard,
Sven