Iterators for D

[nazo]

 >interface Iterator(T) {
 >    bool step();     // as C# MoveNext
 >    T value;         // getter (rvalue access)
 >    T value(T);      // setter (lvalue access)
 >    int opApply(...) // support foreach style iteration
 >}
I think that this is more better.

interface Iterator(T) {
     bool opNext();     // as C# MoveNext.
                        // also support in pointer with opBack().
     bool opNext(int);  // speed hack
     T opValue;         // getter (rvalue access). also support in pointer
     T opValue(T);      // setter (lvalue access). also support in pointer
     int opApply(...) // support foreach style iteration
}

while(iter.next)//call opNext()
   writefln(*iter);//call opValue()