sclass CFile extends Concept {
  S fileProgID;
  S fileName; // optional, relative (program ID + "/" + file name)

  *() {}
  *(S *fileProgID, S *fileName) {}

  File file() {
    ret getProgramFile(fileProgID, fileName);
  }
  
  bool fileExists() {
    ret file().exists();
  }
  
  void makeDefaultName(S extension) {
    if (fileName != null || loading()) ret;
    if (id == 0) fail("No ID");
    fileProgID = dbProgramID();
    fileName = shortDynClassName(this) + id + addPrefix(".", extension);
  }
}