Nested Repeat loops

[Peter Haworth]

Submitted QCC report 12691  for this.

Pete
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On Sat, Jun 21, 2014 at 3:00 PM, Alex Tweedly <alex at tweedly.org> wrote:

> On 21/06/2014 15:22, Richard Gaskin wrote:
>
>> At the RevLive conference in Vegas a few yeas back, Robert Cailliau's
>> opening keynote covered some of the most adventurous feature requests I've
>> ever heard anyone suggest for xTalks.
>>
>> Among them was the notion of named control structures, in part for
>> exactly the reason covered in this thread, the desire to exit a specific
>> loop when loops are nested.
>>
>> I can't recall the specifics of his proposed syntax, but I remember being
>> impressed by how natural it seemed.  Maybe it was along the lines of:
>>
>>   repeat with i = 1 to tSomething named "MySomethingLoop"
>>       repeat with j = 1 to tSomethingElse named "MyOtherLoop"
>>         DoSomethingWith i,j
>>         exit "MySomethingLoop"
>>       end repeat
>>   end repeat
>>
>> With named control structures we'd never need to worry about line numbers.
>>
>> I'm not sure if that was submitted as a feature request, but IMO it
>> should be.  And it would be cool to have just about everything else he
>> proposed go into the DB as well - all of it was valuable, very
>> forward-thinking, reflecting the best of many other languages, all
>> presented in a very xTalk way.
>>
> I believe it would be even better to (be able to) name both ends of the
> control structure, and thereby get some extra help from the compiler if
> there was any mismatch, as well as a better visual clue when reading the
> code. (Without this, when you see an "exit repeat 'name'" statement you
> need to look backwards to see the named control structure, and then
> forwards to find the matching end; far easier to have the name at the end
> as well).
>
>   repeat for each key K in myArray named "arrayloop"
>       repeat with i = 1 to 1000
>          if someFunc(K,i) then
>              doit K, i
>              next repeat "arrayloop"
>          end if
>      end repeat
>      if something() then exit repeat "arrayloop"
>   end repeat named "arrayloop
>
> IMO, either or both named clauses should be optional - no need to put in
> both unless you choose to do the extra work for the extra convenience of
> compiler checks, cf. explicitvariables.
>
> -- Alex.
>
>
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