Using a range as a reference

[Paolo Invernizzi]

Hi all,

I've a custom generator, and is modelled as a structure 
forwardRange, and I want to be able to use it like this, printing 
the first ten fibonacci:

---
struct ForEacher(Range){
     Range* r;
     this(ref Range r_){ r=&r_; }
     @property bool empty(){ return r.empty; }
     @property auto front(){ return r.front; }
     void popFront(){ r.popFront(); }
}
auto forEacher(Range)(ref Range r){
     return ForEacher!Range(r);
}
void main(){
     auto fib = recurrence!("a[n-1] + a[n-2]")(1, 1);

     foreach(e; fib.forEacher){
         static i = 0; i++; if(i == 5) break;
         writeln(e);
     }
     foreach(e; fib.forEacher){
         static j = 0; j++; if(j == 5) break;
         writeln(e);
     }

     or

     writeln(fib.forEacher.take(5));
     writeln(fib.forEacher.take(5));

}
---

There's something in phobos like the 'forEacher'? What is the 
best strategy for something like that?