With a multiple expression switch statement, the associated case is
executed if any expression is equal to the switch expression. For a
multiple expression select, would all channel expressions have to proceed
for the associated case to execute?
e.g.
select {
case x := <-c1, y := <-c2:
// is it guaranteed that both c1 and c2 have produced a value, or just
one or the other?
}
What about send operations?
select {
case c1 <- 10, c2 <- 20:
// is this only executed if both sends happened?
}
Jason
On Thursday, December 21, 2017 at 9:04:35 AM UTC-5, matthe...@gmail.com
wrote:
>
> First the switch behavior surprised me when looking at how to stack cases,
> but then later I was surprised that select doesn't have the same thing.
> Consistency is the only reason to write it down, my concrete example
> doesn't need this as shown by Damien in the proposal.
>
> Matt
>
> On Wednesday, December 20, 2017 at 6:51:36 PM UTC-6, Rob 'Commander' Pike
> wrote:
>>
>> There is no particular reason, it was just to keep things simple, if it
>> was even talked about. I don't think it was.
>>
>> If you want to propose a change, now is a good time to do that. Not sure
>> the idea is above the bar, though.
>>
>> -rob
>>
>>
>>
>>
>> On Thu, Dec 21, 2017 at 9:39 AM, <matthe...@gmail.com> wrote:
>>
>>> Tracker proposal for this: https://github.com/golang/go/issues/23196
>>>
>>> Matt
>>>
>>> On Monday, December 18, 2017 at 10:11:02 AM UTC-6, matthe...@gmail.com
>>> wrote:
>>>>
>>>> I guess with select you can't do the comma for multiple cases having
>>>> one behavior like with switch:
>>>>
>>>> select{
>>>> case <-c1, <-c2: // gofmt: expected 1 expression
>>>> fmt.Println("c1 or c2")
>>>> case <-c3:
>>>> }
>>>>
>>>> switch s{
>>>> case v1, v2:
>>>> fmt.Println("v1 or v2")
>>>> case v3:
>>>> }
>>>>
>>>> I assume this is because select cases have an optional var assignment.
>>>> This would have been nice for detecting an explicit client cancel action
>>>> versus a w.(http.CloseNotifier).CloseNotify() where the resulting server
>>>> action is the same.
>>>>
>>>> Matt
>>>>
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>>
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