Shout out to D at cppcon, when talkign about ranges.

[bitwise via Digitalmars-d]

On Thursday, 1 October 2015 at 00:42:43 UTC, lobo wrote:
> If ranges are accepted into ISO C++ I can't imagine it would be 
> long before for(auto e:range).


Special features are not necessary to do this. C++ for loop works 
on anything with begin()/end() functions. Real ranges could just 
be a pair of iterators, and lazy ranges could give out dummies:

template<class T>
struct iota
{
     T first, last;

     iota(T first, T last)
         : first(first), last(last) {}

     T front() const { return first; }
     void popFront() { ++first; }
     bool empty() const { return first == last; }

     struct iterator {
         iota *_iota;

         bool operator!=(const iterator& that) const {
             assert(_iota == that._iota);
             return !_iota->empty();
         }

         void operator++() {
             _iota->popFront();
         }

         T operator*() const {
             return _iota->front();
         }
     };

     iterator begin() { return iterator{this}; }
     iterator end() { return iterator{this}; }
};

int main(int argc, const char * argv[])
{
     for(int x : iota<int>(0, 5))
         printf("%d ", x);

     return 0;
}

I don't think it would be that hard to make something this 
possible:

for(int x : iota<int>(0, 5).to<take>(3))
     printf("%d ", x);

The iterator dummy could probably be generalized with a template.

      Bit