[swift-evolution] use standard syntax instead of "do" and "repeat"

[Howard Lovatt]

-1. Doesn’t seem worthwhile. There aren’t that many use cases were your code gets littered with try and it is nice to identify exactly what is throwing.

Sorry,

 — Howard.

> On 4 Jan 2016, at 2:52 PM, Andrew Duncan via swift-evolution <swift-evolution at swift.org> wrote:
> 
> 
>> On 3 Jan, 2016, at 10:51, David Waite <david at alkaline-solutions.com> wrote:
>> 
>> One possible approach if it was desirable to not have this used arbitrarily in place of do+try, and to avoid looking too much like exception syntax: instead define rethrows blocks:
>> 
>>  func recognizeHandler() throws {
>>      rethrows {
>>           accept(.on)        
>>           recognizeName()
>>           recognizeFormalParamSeq()
>>           accept(.newline)
>>           recognizeCommandSeq()
>>           accept(.end)
>>           recognizeName()   
>>           accept(.newline)
>>      }
>>  }
> 
> Not bad, modulo all the subsequent reasonable comments, of course.
> 
> It is worth pointing out that (some would say) this is not error-handling at all. It’s a normal part of the recognizer life-cycle that it finds a syntax error in the source code. True, it is the (l)user’s error, but not mine. (Those have full-on asserts. Hey, could we have Eiffel-style contracts? Oops, new thread.)
> 
> What I am after here is a quick-and-clean way to unwind the stack. My throwing recognizer has about 200 “try” statements in it. I tried (NPI) this both with exceptions and with Optional return values. Hard to say which I prefer. But is it not more or less the same underneath the hood? I gather that Swift adds an extra return value for throwing functions.
> 
> 
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