On 26-09-17 11:51, STINNER Victor wrote:
> 
> STINNER Victor added the comment:
> 
> I'm not confortable with the change because of following questions:
> 
> * It seems like your patch changes the SelectSelector behaviour on Windows. How is a selectors user supposed to upgrade his/her code to get the same behaviour on Python 3.6 and 3.7? Would it make sense to add a flag to SelectSelectors get the old behaviour?
The wrapper method around the winsock select method causes 
SelectSelector to behave differently on Windows, which is wrong IMHO. 
The behaviour should be the same. Why this wrapper exists is unclear to 
me and since it conflicts with the change I want to make, I asked 
questions about it 8 weeks ago. Now time has passed and no answers were 
given, I decided to remove it. Without further documentation I do not 
know how to modify it otherwise.

The other solution would be to add the new feature to all OS's but 
Windows, but again, since the wrapper method defies logic and is 
undocumented, I chose to remove it.
> 
> * KqueueSelector doesn't support urgent event. How is a selectors user suppose to be aware of them? Use a blacklist of selectors which doesn't support urgent events? This list might evolve in the future, so maybe the selector should announce which events are supported?
KqueueSelector raises a ValueError on registering an invalid event. 
Accepted events defined in the base class are READ, WRITE and URGENT. 
Accepted events is overruled in KQueueSelector, allowing only READ and 
WRITE.

> 
> * This change alone is going to change asyncio behaviour on Windows, no? Because of the SelectSelector behaviour change on Windows.
Reviewing the documentation of winsock select, I can think of no reason 
why this should change the runtime behaviour of SelectSelector, as well 
as asyncio.
> 
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> <https://bugs.python.org/issue30844>
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