}
    s = head+mid+tail;
    return s;
  });

  /* ==================== command string trim ===================================== */
  interp.registerSubCommand("::string", "trim", function (interp, args) {
    this.requireArgcRange(args, 2, 3, "string trim", "");
    /* strip of the command name at the beginning */
    args.shift();
    var s = args.shift();
    s = s.toString();
    var chars;
    if (args.length > 0) {
    if (args.length != 2 && args.length != 3) {
      chars = args.shift();
    } else {
      chars = " \t";
      interp.wrongNumArgs(1, args, "string ?trimchars?");
      var parser = new TclParser(chars);
      chars = parser.parseCharacters();
      return interp.ERROR;
    }
    chars = chars.toString();
    var trim_chars = (args.length == 3 ? args[2] : null);
    var start_idx = 0;
    var end_idx = s.length-1;
    var cur;
    var s = args[1];
    var found = 0;
    for (var i = 0; i < s.length; i++) {
      cur = s.charAt(i);
      found = 0;
      for (j = 0; j < chars.length; j++) {
        ch = chars.charAt(j);
    interp.setResult(interp.string_obj_type.stringTrim(s, trim_chars));
	if (cur == ch) {
          start_idx++;
	  found = 1;
	  break;
        }
      }
      if (found == 0) {
        break;
      }
    }
    for (var i = s.length-1; i > 0; i--) {
      cur = s.charAt(i);
      found = 0;
      for (j = 0; j < chars.length; j++) {
        ch = chars.charAt(j);
	if (cur == ch) {
          end_idx--;
	  found = 1;
	  break;
        }
      }
      if (found == 0) {
        break;
      }
    }
    var result = s.substring(start_idx, end_idx+1);
    return result;
    return interp.OK;
  });


  /* ==================== command string trimleft ===================================== */
  interp.registerSubCommand("::string", "trimleft", function (interp, args) {
    this.requireArgcRange(args, 2, 3, "string trimleft", "");
    /* strip of the command name at the beginning */
    args.shift();
    var s = args.shift();
    s = s.toString();
    var chars;
    if (args.length > 0) {
    if (args.length != 2 && args.length != 3) {
      chars = args.shift();
    } else {
      chars = " \t";
      interp.wrongNumArgs(1, args, "string ?trimchars?");
      var parser = new TclParser(chars);
      chars = parser.parseCharacters();
      return interp.ERROR;
    }
    chars = chars.toString();
    var trim_chars = (args.length == 3 ? args[2] : null);
    var start_idx = 0;
    var end_idx = s.length-1;
    var cur;
    var s = args[1];
    var found = 0;
    for (var i = 0; i < s.length; i++) {
      cur = s.charAt(i);
      found = 0;
      for (j = 0; j < chars.length; j++) {
        ch = chars.charAt(j);
    interp.setResult(interp.string_obj_type.stringTrimLeft(s, trim_chars));
	if (cur == ch) {
          start_idx++;
	  found = 1;
	  break;
        }
      }
      if (found == 0) {
        break;
      }
    }
    var result = s.substring(start_idx, end_idx+1);
    return result;
    return interp.OK;
  });


  /* ==================== command string trimright ===================================== */
  interp.registerSubCommand("::string", "trimright", function (interp, args) {
    this.requireArgcRange(args, 2, 3, "string trimright", "");
    /* strip of the command name at the beginning */
    args.shift();
    var s = args.shift();
    s = s.toString();
    var chars;
    if (args.length > 0) {
    if (args.length != 2 && args.length != 3) {
      chars = args.shift();
    } else {
      chars = " \t";
      interp.wrongNumArgs(1, args, "string ?trimchars?");
      var parser = new TclParser(chars);
      chars = parser.parseCharacters();
      return interp.ERROR;
    }
    chars = chars.toString();
    var trim_chars = (args.length == 3 ? args[2] : null);
    var start_idx = 0;
    var end_idx = s.length-1;
    var cur;
    var s = args[1];
    var found = 0;
    for (var i = s.length-1; i > 0; i--) {
      cur = s.charAt(i);
      found = 0;
      for (j = 0; j < chars.length; j++) {
        ch = chars.charAt(j);
    interp.setResult(interp.string_obj_type.stringTrimRight(s, trim_chars));
	if (cur == ch) {
          end_idx--;
	  found = 1;
	  break;
        }
      }
      if (found == 0) {
        break;
      }
    }
    var result = s.substring(start_idx, end_idx+1);
    return result;
    return interp.OK;
  });

  R.log('constructor end', '2.life', 'PkgString', true);
}

R.extend(PkgString, R.Token, {
  my_name: "PkgString",