gistfile1.txt

define(function() {

  // https://gist.github.com/addyosmani/1057989

  /**
   Code copyright Dustin Diaz and Ross Harmes, Pro JavaScript Design Patterns.
   **/

  // Constructor.
  var Interface = function(name, methods) {
    if (arguments.length !== 2) {
      throw new Error("Interface constructor called with " + arguments.length + "arguments, but expected exactly 2.");
    }
    this.name = name;
    this.methods = [];
    for (var i in methods) {
      if (methods.hasOwnProperty(i)) {
        if (typeof i !== 'string' || typeof methods[i] !== 'object' ||
            methods[i].constructor.toString().substr(9, 7) !== 'Array()') {
          throw new Error("Interface constructor expects method to be " +
              "passed in as a key value pairs.");
        }
        this.methods[i] = methods[i];
      }
    }
  };

  Interface.DEBUG = true;
  Interface.OBJECT_PROPERTY = true;
  Interface.PROPERTY_KEY = 'interfaces';

  var ifIndex = 0;

  // Static class method.
  Interface.ensureImplements = function(ifaces, object) {
    if (Interface.OBJECT_PROPERTY) {
      object[Interface.PROPERTY_KEY] = [];
    }

    for (var i = 0, len = ifaces.length; i < len; i++) {
      var iface = ifaces[i];
      if (iface.constructor !== Interface) {
        iface = new Interface('__' + ifIndex, iface);
      }
      for (var method in iface.methods) {
        if (iface.methods.hasOwnProperty(method)) {
          var args = iface.methods[method];
          if (!object[method] || typeof object[method] !== 'function') {
            throw new Error("Function Interface.ensureImplements: object " +
                "does not implement the " + iface.name + " interface. Method " + method + " was not found.");
          }

          if (Interface.DEBUG) {
            object[method] = (function(method, args) {
                return function() {
                  for (var i = 0; i < args.length; i += 1) {
                    if (arguments.length <= i || !(arguments[i] instanceof args[i])) {
                      throw new Error("Called method \"" + method +
                          "\" - argument #" + i + " not passed or has invalid type");
                    }
                  }
                  return this[method].apply(this, arguments);
                };
              })(method, args);
          }
        }
      }

      if (Interface.OBJECT_PROPERTY) {
        object[Interface.PROPERTY_KEY].push(iface);
      }
    }

    return object;
  };

  return Interface;
});