[swift-users] Using defer in Swift Playgrounds

[Jordan Rose]

I’d say that’s a bug! Mind filing it at https://bugs.swift.org <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>
> 
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