concept G22LeftArrowScript > ConceptWithChangeListeners {
  settableWithVar S description;
  
  // the script (last "saved" version)
  settableWithVar S text;
  
  // the latest code that has been cleared to auto-run (if any)
  settableWithVar ClearForAutoRun<S> autoRunnableVersion;

  // text currently being modified in an editor (or null)
  // Note that "" doesn't count as null.
  settableWithVar S editingText;
  
  {
    varEditingText().onChange(r {
      editingText(eq(latestText, text) ? null : latestText);
    });
  }
  
  @Override void _doneLoading2() {
    //print("_doneLoading " + this);
    cMigrateField(this, "code", "text");
  }
  
  S myType() { ret dropPrefix("G22", shortClassName(this)); }
  
  toString { ret or2(description, myType() + " " + id); }
  
  S latestText() { ret or(editingText, text); }
  S stableText() { ret text; }
  
  File historyFile() {
    ret fileInConceptsDir("History/" + shortDynName(this) + id + ".history");
  }
  
  void saveTextToHistory() {
    File historyFile = assertNotNull(+historyFile());
    S text = this.text;
    appendToTextFile(historyFile,
      "\n===\n" +
      "Concept ID: " + id + "\n" +
      "Date: " + dateWithMSUTC() + "\n" +
      "Text (" + nLines(text) + ", " + nChars(text) + "):\n" +
      indentx(text) + "\n" +
      "\n" +
      "===" + "\n");
  }
  
  void _onChange :: after {
    lvLatestText?.set(latestText());
  }
}