import std.stdio;
class Foo {
  int a;
  int opApply(scope int delegate(ref int) dg)const
  {
    auto r = dg(a);
    if (r) return r;
    return 0;
  }
}
class Bar {
  Foo foo;
  this(){ foo = new Foo; }
  void hoge() const
  {
    writeln(foo.a);
    foreach(ref fuga; foo){
      fuga = 1;
    }
    writeln(foo.a);
  }
}
void main() {
  (new Bar()).hoge();
}