[fpc-pascal] Changing iterator usage pattern in FCL-STL

Michael Van Canneyt michael at freepascal.org
Sun Nov 8 22:37:50 CET 2015

On Sun, 8 Nov 2015, Sven Barth wrote:

> On 08.11.2015 19:38, leledumbo wrote:
>> FCL-STL from the start has different iterator usage pattern compared to
>> existing containers (say a TSQLQuery). i.e. the common pattern is:
>> It := SomeContainer.Iterator;
>> while not It.EOF do begin
>>    ...
>>    It.Next;
>> end;
>> instead, it uses:
>> It := SomeContainer.Iterator;
>> repeat
>>    ...
>> until not It.Next;
>> Examining the iterator code, I can see that the latter has at least the
>> following disadvantage:
>> One must add additional guard before executing repeat-until to make sure
>> that the container has at least 1 data. Otherwise, Next in until expression
>> will trigger EAccessViolation.
>> I would like to change the pattern to follow existing one. However, FCL-STL
>> has been available for some time now that changing the pattern will break
>> existing code. How do you think I should proceed on this one?
> I'd say don't change. In my opinion the need to restructure one's code 
> outweighs that disadvantage. If anything then add a for-in compatible 
> iterator like was done for TVector<>.

Enumerator, you mean ?


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