// only works within a module
sclass StandardClasses is AutoCloseable {
  volatile SS map;
  AutoCloseable updater;

  *() {  
    updater = dm_onSnippetEdited(voidfunc(S id) {
      if (contains(standardClassesSnippetIDs(), fsI(id)))
        map = null;
    });
  }
  
  // name to snippetID
  SS getMap() {
    if (map == null) map = standardClassesMap_uncached();
    ret map;
  }
  
  public void close {
    dispose updater;
  }
}

Began life as a copy of #1032676