RFC on range design for D2

[Denis Koroskin]

On Wed, 10 Sep 2008 01:56:40 +0400, Andrei Alexandrescu  
<SeeWebsiteForEmail at erdani.org> wrote:

> Andrei Alexandrescu wrote:
>> Manfred_Nowak wrote:
>>> Benji Smith wrote:
>>>
>>>> Given the use of "getNext", I think "hasNext" is a more natural
>>>> choice
>>>
>>> clapping hands.
>>  Walter would love that.
>>  for (R r = getR(); r.hasNext; r.next) { ... }
>>  Look ma, no negation! Oops, I just materialized one with the  
>> exclamation sign.
>
> I just discovered a problem with that. hasNext implies I'm supposed to  
> call next to get the thingie. It should be hasFirst, which is less  
> appealing.
>
> Andrei

I usually implement my iterators as follows:

interface Iterator(T) {
     bool isValid();
     T value();
     void moveNext();
}

Usage:

auto it = ...;
while (it.isValid()) {
     auto value = it.value();
     it.moveNext();
}

or

for (auto it = ...; it.isValid(); it.moveNext()) {
     auto value = it.value();
}