If I wrote this:
if serverCert.write(to: certificateUrl) { showErrorInKeyWindow(message); return
}
then the meaning of return would have been different.
Imo it is a problem that two pieces of code impact the understanding of each
other and that those two pieces of code could potentially be very far apart.
I do agree that the parenthesis are not a perfect solution, it was just the
first thing that I could think of and that has some level of similarity in
meaning.
Regards,
Rien
Site: http://balancingrock.nl
Blog: http://swiftrien.blogspot.com
Github: http://github.com/Balancingrock
Project: http://swiftfire.nl
> On 15 Mar 2017, at 12:00, Adrian Zubarev <[email protected]>
> wrote:
>
> I’m slightly confused by this. How is a trailing closure different from a
> code block in Swift? It’s basically the same thing with some extra syntax
> sugar because it happens to be the last parameter of your function.
>
> You can simply write this if you wanted to:
>
> myFucntion(someLabel: abc, closureLabel: { …; return })
>
> Parentheses are indicating that your closure is immediately invoked.
>
> let someInt = { return 42 }()
> print(someInt)
>
> let someClosureWhichReturnsAnInt = { return 42 } // You can reuse the closure
> print(someClosureWhichReturnsAnInt()) // Invocation happens now here
>
> return is scope based and it’s totally clear (to me) that in your case return
> will return from your closure with a value of Void.
>
>
>
>
> --
> Adrian Zubarev
> Sent with Airmail
>
> Am 15. März 2017 um 11:35:39, Rien via swift-evolution
> ([email protected]) schrieb:
>
>> What does the following code fragment do?
>>
>> serverCert.write(to: certificateUrl) { showErrorInKeyWindow(message); return
>> }
>>
>> The only possible answer is: I don’t know.
>>
>> 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:
>>
>> 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
>>
>>
>>
>>
>>
>> _______________________________________________
>> swift-evolution mailing list
>> [email protected]
>> https://lists.swift.org/mailman/listinfo/swift-evolution
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