sclass HCRUD_Data {
  new Map<S, Renderer> renderers;
  new SS fieldHelp;
  
  abstract sclass Renderer {}
  srecord TextArea(int cols, int rows) extends Renderer {}
  srecord TextField(int cols) extends Renderer {}
  srecord ComboBox(LS entries) extends Renderer {}
  srecord CheckBox() extends Renderer {}

  S itemName() { ret "object"; }
  S itemNamePlural() { ret plural(itemName()); }
  
  //LS fields() { null; }
  L<Map<S, O>> list() { null; }
  S fieldNameToHTML(S name) { ret htmlencode(humanizeLabel(name)); }
  S idField() { ret "id"; }
  Map<S, O> emptyObject() { null; }
  Map<S, O> getObject(O id) { null; }
  
  // return ID
  O createObject(SS map) { throw unimplemented(); }
  
  // return text msg
  S deleteObject(O id) { throw unimplemented(); }
  
  // return text msg
  S updateObject(O id, SS map) { throw unimplemented(); }
  
  // return null for standard input field
  Renderer getRenderer(S field) { ret renderers.get(field); }
  
  // returns HTML
  S fieldHelp(S field) { ret fieldHelp.get(field); }
  
  returnSelf addRenderer(S field, Renderer renderer) { renderers.put(field, renderer); }
  
  returnSelf fieldHelp(S field, S help) { fieldHelp.put(field, help); }
}