[swift-users] Using defer in Swift Playgrounds

[Joe DeCapo]

Since it's Playground bug, should I file it in Apple's bug reporter rather than Swift's?

> On Aug 7, 2017, at 3:12 PM, Jordan Rose <jordan_rose at apple.com> wrote:
> 
> I’d say that’s a bug! Mind filing it at https://bugs.swift.org ?
> 
> Thanks,
> Jordan
> 
>> On Aug 4, 2017, at 12:41, Joe DeCapo via swift-users <swift-users at swift.org> wrote:
>> 
>> Hi everyone,
>> 
>> I'm not sure if there's a more appropriate place to ask this question, but I figured at the very least I could get pointed in the right direction. I've tried searching online and haven't been able to find anything addressing this.
>> 
>> I was trying to use the `defer` statement in a Playground, and was surprised to find that it never prints anything in the preview pane on the side. I was expecting the evaluation of the code in the `defer` statement to show up in line with the statements, even though they're executed after the last line in the function. I made a very simple playground that modifies a global variable and prints the value in the `defer` statement, and when I print the global variable after calling my function it shows the correct updated value, so the code in the `defer` statement is getting run as expected. Here's my sample code with the Playground output in comments on the side:
>> 
>> var x = 3			// 3
>> func doSomething() {
>>   print(1)			// "1\n"
>>   defer {
>>       x += 1
>>       print(x)
>>   }
>>   print(2)			// "2\n"
>> }
>> doSomething()
>> print(x)			// "4\n"
>> 
>> I was expecting something like this:
>> 
>> var x = 3			// 3
>> func doSomething() {
>>   print(1)			// "1\n"
>>   defer {
>>       x += 1			// 4
>>       print(x)			// "4\n"
>>   }
>>   print(2)			// "2\n"
>> }
>> doSomething()
>> print(x)			// "4\n"
>> 
>> Is there some deep reason why code in `defer` statements doesn't show anything in the preview pane in Playgrounds?
>> 
>> -Joe
>> 
>> <Defer.playground>
>> 
>> _______________________________________________
>> swift-users mailing list
>> swift-users at swift.org
>> https://lists.swift.org/mailman/listinfo/swift-users
>