// progID is just for information

static class JavaXClassLoader extends URLClassLoader {

  S progID;

  Set<File> files = syncLinkedHashSet();

  Set<S> libraryIDs = syncLinkedHashSet();

  Set<S> triedToLoad = synchroSet();

  Set<Class> loadedClasses = synchroSet();

  bool retired;

  O retiredMarker;

  IF1<S, Class> findClass_extension;

  S mainClassName;

  bool verbose;

  *(S progID, L<File> files) {

    this(progID, files, getSystemClassLoader());

  }

  *(S progID, L<File> files, ClassLoader parent) {

    // sadly can't see this constructor

    //super(progID, new URL[0], parent, vm_globalACC());

    super(new URL[0], parent);

    this.progID = progID;

    fOr (File f : files)

      addFile(f);

    // TODO: how to get around this

    fixACCInClassLoader(this);

  }

  Class<?> super_findClass(S name) throws ClassNotFoundException {

    ret super.findClass(name);

  }

  protected Class<?> findClass(S name) throws ClassNotFoundException {

    if (verbose) System.out.println(this + " findClass: " + name);

    if (findClass_extension != null) {

      Class<?> c = findClass_extension.get(name);

      if (verbose) System.out.println("extension returned: " + c);

      if (c != null) ret c;

    }

    bool triedBefore = !triedToLoad.add(name);

    try {

      Class<?> c = super.findClass(name);

      if (verbose) System.out.println("super.findClass returned: " + c);

      loadedClasses.add(c);

      if (eq(name, mainClassName()))

        callOpt(javax(), 'registerAMainClass, c);

      ret c;

    } catch (ClassNotFoundException e) {

      if (verbose) System.out.println(getStackTrace(e));

      throw new ClassNotFoundException("Class " + name + " not found in " + joinWithComma(map f2s(files)) + " (progID=" + progID + ")"

        + (triedBefore ? ", tried to load before" : ""), e);

    }

  }

  toString {

    ret shortClassName(this) + "[" + systemHashCodeHex(this) + "] - " + progID;

  }

  S mainClassName() {

    if (mainClassName == null) {

      mainClassName = "main";

      pcall {

        mainClassName = or2(trim(loadTextFileResource(this, "main-class")), mainClassName);

      }

    }

    ret mainClassName;

  }

  bool addFile(File f, S libraryID) {

    if (nempty(libraryID))

      if (!libraryIDs.add(libraryID))

        false;

    ret addFile(f);

  }

  bool addFile(File f) ctex {

    if (!files.add(f)) false;

    addURL(f.toURI().toURL());

    mainClassName(); // calculate early. no good loading text files later

    true;

  }

  Set<S> libraryIDs() { ret libraryIDs; }

  bool hasLibraryID(S libraryID) { ret libraryIDs.contains(libraryID); }

  protected swappable S findLibrary(S libname) { ret super.findLibrary(libname); }

  // make public

  public void addURL(URL url) {

    super.addURL(url);

  }

}