[swift-users] [Feature Request] Extend the `defer` statement

[Jun Zhang]

Yes that's true, but this requires me to set a return value in every `early
return` statement. I think this should be done by the compiler instead of
me, to make code cleaner and also less error-prone.

On Mon, Oct 9, 2017 at 11:24 AM, Slava Pestov <spestov at apple.com> wrote:

> I think you can achieve what you want by having the ‘defer’ block capture
> a mutable local variable. Eg,
>
> func doStuff() {
>   var success = false
>
>   defer {
>     if !success {
>       // do some additional cleanup
>     }
>   }
>
>   …
>   success = true
>   …
>
>   return result
> }
>
> On Oct 8, 2017, at 7:34 PM, Jun Zhang via swift-users <
> swift-users at swift.org> wrote:
>
> Hi dear swift developers,
>    I am kind of new to swift and I don't know if this feature already
> exists. And if it exists already please tell me how. Thank you very much!
>   The feature is to capturing the return value (maybe input value also) of
> the function. Here is the demo code:
>
>     func tableView(_ tableView: UITableView, numberOfRowsInSection
> section: Int) -> Int {
>         defer {
>             if $> >= 0 {
>                 // table is not empty
>             }
>             else {
>                 // table is empty
>             }
>         }
>         return dataSource.cout
>     }
>
>    I suggest using `$>` as the return value symbol and `$<` as the input
> parameter symbol.
>    Thank you all and best regards to you!
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>
>
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