static long objectID(O o) {
  if (o == null) ret 0;
  Map generalMap = vm_generalMap();
  if (generalMap == null) fail("Please upgrade JavaX");
  synchronized(generalMap) {
    Map map = cast generalMap.get("objectIDs");
    if (map == null) {
      pcall-short {
        map = (Map) nuForeignObject(javax(), className(javax()) + '$WeakIdentityHashMap);
      }
      if (map == null) map = new WeakIdentityHashMap; // older JavaX
      generalMap.put("objectIDs", map);
    }
    Long l = cast map.get(o);
    if (l == null) {
      l = toLong(generalMap.get("lastObjectID"))+1;
      generalMap.put("lastObjectID", l);
      map.put(o, l);
    }
    ret l;
  }
}

static Collection<Long> objectID_liveIDs() {
  Map generalMap = cast getOpt(javax(), 'generalMap);
  if (generalMap == null) ret new L;
  synchronized(generalMap) {
    ret cloneList(values((Map<O, Long>) generalMap.get("objectIDs")));
  }
}