// only works within a module
// has mild race conditions
sclass SnippetInstaCache is AutoCloseable {
  // snippet ID to text
  SS texts = syncMap();
  AutoCloseable updater;

  *(S... snippetIDs) { this(asList(snippetIDs)); }
  
  *(Iterable<S> snippetIDs) {
    updater = dm_onSnippetEdited(voidfunc(S id) {
      bool contained = texts.containsKey(id);
      print("SnippetInstaCache: snippet edited " + id + ", contained: " + contained);
      if (contained)
        texts.put(id, loadSnippet(id));
    });
    
    fOr (snippetID : map fsI(snippetIDs))
      texts.put(snippetID, loadSnippet(snippetID));
  }
  
  // get snippet text
  S get(S snippetID) {
    ret texts.get(fsI(snippetID));
  }
  
  close { dispose updater; }
  
  Cl<S> cachedSnippetIDs() { ret cloneKeys(texts); }
}