[swift-users] Using defer in Swift Playgrounds

[Joe DeCapo]

Here's the JIRA: https://bugs.swift.org/browse/SR-5641

Thanks again!
-Joe

> On Aug 7, 2017, at 3:33 PM, Joe DeCapo via swift-users <swift-users at swift.org> wrote:
> 
> Ok, cool. Thanks for the response. I'll file it in the Swift bug tracker.
> 
>> On Aug 7, 2017, at 3:23 PM, Jordan Rose <jordan_rose at apple.com> wrote:
>> 
>> Either way is fine. I suspect this is a bug with the transformation the Swift compiler performs when compiling for a playground, rather than with the machinery that goes with running the playground, but I haven’t looked into it.
>> 
>> Jordan
>> 
>> 
>>> On Aug 7, 2017, at 13:22, Joe DeCapo <snoogansbc at gmail.com> wrote:
>>> 
>>> 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
>>>> 
>>> 
>> 
> 
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