//static final Map<Class, HashMap<S, Field>> getOpt_cache = newDangerousWeakHashMap(f getOpt_special_init);

sclass getOpt_Map extends WeakHashMap {
  *() {
    if (getOpt_special == null) getOpt_special = new HashMap;
    clear();
  }
  
  public void clear() {
    super.clear();
    //print("getOpt clear");
    put(Class.class, getOpt_special);
    put(S.class, getOpt_special);
  }
}

static final Map<Class, HashMap<S, Field>> getOpt_cache = 
  ifdef AssumeNoClassUnloading
    syncHashMap();
  endifdef
  ifndef AssumeNoClassUnloading
    _registerDangerousWeakMap(synchroMap(new getOpt_Map));
  endifndef
  
static HashMap getOpt_special; // just a marker

/*static void getOpt_special_init(Map map) {
  map.put(Class.class, getOpt_special);
  map.put(S.class, getOpt_special);
}*/

static Map<S, Field> getOpt_getFieldMap(O o) {
  Class c = _getClass(o);
  HashMap<S, Field> map = getOpt_cache.get(c);
  if (map == null)
    map = getOpt_makeCache(c);
  ret map;
}

static Object getOpt_cached(Object o, String field) ctex {
  if (o == null) ret null;

  Map<S, Field> map = getOpt_getFieldMap(o);

  if (map == getOpt_special) {
    if (o instanceof Class)
      return getOpt((Class) o, field);
    /*if (o instanceof S)
      ret getOpt(getBot((S) o), field);*/
    if (o instanceof Map)
      ret ((Map) o).get(field);
  }
    
  Field f = map.get(field);
  if (f != null) ret f.get(o);
  ifclass DynamicObject
    if (o instanceof DynamicObject)
      ret syncMapGet2(((DynamicObject) o).fieldValues, field);
  endif
  ret null;
}

// used internally - we are in synchronized block
static HashMap<S, Field> getOpt_makeCache(Class c) {
  HashMap<S, Field> map;
  if (isSubtypeOf(c, Map.class))
    map = getOpt_special;
  else {
    map = new HashMap;
    new HashSet<Class> interfaces;
    if (!reflection_classesNotToScan().contains(c.getName())) {
      Class _c = c;
      do {
        for (Field f : _c.getDeclaredFields()) {
          makeAccessible(f);
          S name = f.getName();
          if (!map.containsKey(name))
            map.put(name, f);
        }
        for (intf : c.getInterfaces())
          interfaces.add(intf);
        _c = _c.getSuperclass();
      } while (_c != null);
      
      // Scan interfaces for static final fields
      
      for (intf : interfaces) {
        for (Field f : intf.getDeclaredFields()) {
          makeAccessible(f);
          S name = f.getName();
          if (!map.containsKey(name))
            map.put(name, f);
        }
      }
    }
  }
  
  if (getOpt_cache != null) getOpt_cache.put(c, map);
  ret map;
}

Began life as a copy of #1005583