Feature Request: add some version of "type erasure" range/iterator

[Ilya Murav'jov <muravev@…>]

Hi!

I successfully use B.Lambda/B.Function for closure functionality in my code and would like to do the same with complex iterators/ranges . I've successfully implemented such "any" iterator range on top of any_iterator ( thanks to ​http://thbecker.net/free_software_utilities/type_erasure_for_cpp_iterators/start_page.html ), see ​any_range.h . The common use case is as follows (my real code, ​select.cpp):

  fe::range<Comp::MediaObj*> SelectedMediaObjs(MenuRegion& mn_rgn, const int_array& sel_arr)
  {
      return fe::make_any( sel_arr | fe::transformed(ToMOTransform(mn_rgn)) );
  }
  fe::range<Comp::MediaObj*> SelectedMediaObjs(MEditorArea& edt_area)
  {
      return SelectedMediaObjs(edt_area.CurMenuRegion(), edt_area.SelArr());
  }

  ...
  // somewhere else
  ...
  BOOST_FOREACH( Comp::MediaObj* obj, SelectedMediaObjs(edt_area) )
  {
      res_mi = obj->MediaItem();
      break;
  }

[Neil Groves]

Implementation added to the trunk.