ECMA Script 6のgeneratorを使ってIoC (Inversion of Control)。node v0.11.4で--harmony-generatorsオプションをつけて実行。

ioc.js

/*
 * IoC (Inversion o Control) Computation Expression
 */

function ioc(fn) {
  assert(isGeneratorFunction(fn), 'The argument `fn` must be a GeneratorFunction.');

  run.mflow_generatorFunction = fn;
  return run;
 
  function run(container) {
    return function () {
      var gen = fn.apply(this, arguments);
      var ret = gen.next();
      var component;
      while (!ret.done) {
        if (typeof ret.value === 'string') {
          component = container[ret.value];
          if (component != null) {
            component = normalize(component, container);
            ret = gen.next(component);
          } else {
            get.throw(new Error('The component is not found. key = "') + ret.value + '"');        
          }
        } else {
          get.throw(new Error('The yieldable value must be a string'));        
        }
      }
      return ret.value;        
    };
  }

  function normalize(obj, container) {
    if (obj && obj.mflow_generatorFunction) obj = obj.mflow_generatorFunction;
    if (isGeneratorFunction(obj)) {
      obj = ioc(obj);
      obj = obj(container);
    } else if (isFunction(obj)) {
      obj = obj();
    }
    return obj;
  }

  function assert(prerequisite, message) {
    if (prerequisite) return;
    throw new Error(message);
  }

  function isFunction(obj) {
    return typeof obj === 'function';
  }

  function isGeneratorFunction(obj) {
    return obj && obj.constructor && 'GeneratorFunction' === obj.constructor.name;
  }
}


/*
 * MAIN
 */

var flow1 = ioc(function * () {
  var p = yield 'person';
  return JSON.stringify(p);
});

var flow2 = ioc(function * (prefix, suffix) {
  var m = yield 'message';
  return prefix + m.content + suffix;
});

var container = {
  // mutable state
  count: 0,

  // singleton
  person: {
    name: 'foo',
    age: 20
  },

  // singleton
  flow1: flow1,

  // singleton
  flow2: flow2,

  // prototype
  message : function () {
    var count = container.count++;
    return {
      content: 'hello ' + count
    };
  },

};

var main= ioc(function * () {
  var a = yield 'flow1';
  var b = yield 'flow2';
  var c = yield 'flow2';
  console.log(a()); // {"name":"foo","age":20}
  console.log(b('[', ']')); // [hello 0]
  console.log(c('<', '>')); // <hello 1>
});

main(container)();


/*
 * Test using mock
 */

var result = flow1({person: {name: 'test', age: 99}})();
console.log(result); // {"name":"test","age":99}

result = flow2({message: { content: 'dummy'}})('(', ')');
console.log(result); // (dummy)

いくつか改善案

yieldにコンポーネントの名前だけでなくパスを指定できるようにする

yield 'person.name';

コンポーネントが関数の場合にはそいつが属しているコンテナを引数で渡す

var container = {
  child: {
     fn: function (container, parent) {
        ...
     }
  }
};