> On Mar 15, 2017, at 3:35 AM, Rien via swift-evolution
> <swift-evolution@swift.org> wrote:
>
> What does the following code fragment do?
>
> serverCert.write(to: certificateUrl) { showErrorInKeyWindow(message); return }
>
> The only possible answer is: I don’t know.
No, that is incorrect.
The code block in question is either a training closure argument to
serverCert.write(), or it is a syntax error.
We don’t allow ‘naked’ blocks in Swift. If you want to evaluate a closure and
discard it, you have to use ‘_ =‘:
_ = { … }
If you want to just introduce a new lexical scope you have to use the ‘do’
keyword:
do {
stuff
return
}
>
> The problem is finding out what the “return” statement will do.
>
> Without knowing if the {...} is a code block or a trailing closure it is
> impossible to know what the return statement will do. It will either end the
> closure or it will end the function that contains this code block.
>
> This could be disambiguated by using the same syntax as for lazy variables:
There’s no special syntax for lazy variables, this is just a trick for turning
a statement into an expression. It works with non-lazy vars too:
var x = { some statement; return x }()
Slava
>
> serverCert.write(to: serverCertificateUrl) { showErrorInKeyWindow(message:
> message); return }()
>
> Now it is clear that the return statement will only terminate the (trailing)
> closure.
>
> A question to the educators on the list: Is this a real problem?
>
> Personally, I dislike this situation, but I am also ambivalent towards the
> solution I just described.
>
> Regards,
> Rien
>
> Site: http://balancingrock.nl
> Blog: http://swiftrien.blogspot.com
> Github: http://github.com/Balancingrock
> Project: http://swiftfire.nl
>
>
>
>
>
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