Boolean parameters to API functions considered harmful (2011)(jlebar.com)

   gtk_box_pack_start (Box, Widget, bool expand, bool fill, int padding);

    enum GtkBoxPackingOptions
    {
       PACK_SHRINK,
       PACK_EXPAND_PADDING,
       PACK_EXPAND_WIDGET
    };

    foo.frob(true, false, true);

  /* caller */
  doSomething (arg1, arg2, XYZ_SYNC);

  /* platform 1 */
  #define XYZ_SYNC 0
  #define XYZ_ASYNC 0x01

  /* platform 2 */
  #define XYZ_SYNC 0x01
  #define XYZ_ASYNC 0

    document.addObserver(observer, "load", Yes.isWeak);

    xhr.OpenUrl(url, options, No.sync)

    function foo({a = 1, b = 2} = {}) {...}

    foo({a: 1, b: 2}) {...}

    function foo({a = 1, b = 2, c} = {c: 3}) {
      console.log(a, b, c);
    }
    foo();         // 1 2 3
    foo({a: 'a'}); // a 2 undefined
    foo({c: 'c'}); // 1 2 c

    function foo({length = 2} = 'foobar') {
      console.log(length);
    }
    foo();            // 6
    foo({length: 0}); // 0
    foo({x: 'x'});    // 2

    (async ? dispatch_async : dispatch_sync)(queue, ^{
        /* stuff */
     });

  Xhr.open(type, url, Xhr.ASYNC);

  function addObserver(observer, func, { weak = false } = {}) {
    if (weak) {
      // ...
    }
  }

  addObserver(observer, 'load', { weak: true });

   enableOutput(bool)