Design Pattern: Not Just Mixin Pattern

1. Roles：Mixin Source & Mixin Target；

2. Mixin Source将织入自身的所有成员（方法和字段）到Mixin Target；

3. Mixin Source织入的方法必须具备实现，而不仅仅是签名而已；

4. Mixin Source 和 Mixin Target相互独立。就是Mixin Target与Mixin Source互不依赖，Target即使移除Source的成员依然有效，而Source也不针对Target来设计和编码；

5. 若存在签名相同的成员，后来者覆盖前者还是保留，还是以其他规则处理都是正常的；（对象的继承链依然只有一条，因此若存在签名相同的成员，其实还是好办的^_^）

/*!  * defc  * author: fsjohnhuang  * version: 0.1.0  * blog: fsjohnhuang.cnblogs.com  * description: define class with single inheritance, multiple mixins  * sample:  *   defc('omg.JS', {  *     ctor: function(version){  *         this.ver = verison      *     },  *     author: 'Brendan Eich',  *     getAuthor: function(){ return this.author }  *   })  *   var ES5 = defc('omg.ES5', 'omg.JS', {  *        ctor: function(version){}  *   })  *   var mixins = [{isGreat: true, hasModule: function(){return true}}]  *   var ES6 = defc('omg.ES6', ES5, mixins, {  *        ctor: function(version){},  *      getAuthor: function(){  *            var author = zuper() // invoke method of super class which is the same signature  *            return [author, 'JSers']  *      }  *   })  *   var es6 = new ES6('2015')  *   var es6_copy = new ES6('2015')  *   assert.deepEquals(['Branden Eich', 'JSers'], es6.getAuthor())  *   assert.equals(true, es6.isGreat)  *   ES6._mixin({isGreat: false})  *   assert.equals(false, es6_copy.isGreat)  *     *   defc.mixin(es6, {isGreat: true})  *   assert.equals(true, es6.isGreat)  *   assert.equals(false, es6_copy.isGreat)  */ ;(function(factory){         var require = function(module){ return require[module] }         require.utils = {             isArray: function(obj){                 return /Array/.test(Object.prototype.toString.call(obj))             },             isFn: function(obj){                 return typeof obj === 'function'             },             isObj: function(obj){                 return /Object/.test(Object.prototype.toString.call(obj))             },             isStr: function(obj){                 return '' + obj === obj             },             noop: function(){}         }          factory(require, this) }(function(require, exports){     var VERSION = '0.1.0'     var utils = require('utils')      var clazzes = {}      /**      * @method defc      * @public       * @param {DOMString} clzName - the full qualified name of class, i.e. com.fsjohnhuang.Post      * @param {Function|DOMString|Array.<Object>|Object} [zuper|mixins|members] - super class, mixin classes array or members of class      * @param {Array.<Object>|Object} [mixins|members] - mixin classes array or members of class      * @param {Object} [members] - members of class. ps: property "ctor" is the contructor of class      * @returns {Object}      */     var defc = exports.defc = function(clzName, zuper, mixins, members){         if (clazzes[clzName]) return clazzes[clzName].ctor         var args = arguments, argCount = args.length          members = utils.isObj(args[argCount-1]) && args[argCount-1] || {}         mixins = utils.isArray(mixins) && mixins || utils.isArray(zuper) && zuper || []         zuper = utils.isFn(zuper) && zuper || utils.isStr(zuper) && clazzes[zuper] && clazzes[zuper].ctor || 0           var clz = clazzes[clzName] = {}         var ctor = clz.ctor = function(){             // execute constructor of super class             if (zuper) zuper.apply(this, arguments)             // execute constructor             members.ctor && members.ctor.apply(this, arguments)             // contruct public fields             for(var m in members)                  if(utils.isFn(this[m] = members[m])) delete this[m]         }         ctor.toString = function(){ return (members.ctor || utils.noop).toString() }          // extends super class         if (zuper){             var M = function(){}             M.prototype = zuper.prototype             ctor.prototype = new M()                 ctor.prototype.contructor = members.ctor || utils.noop         }          // construct public methods          for(var m in members)             if(m === 'ctor' || !utils.isFn(members[m])) continue             else if(!(zuper.prototype || zuper.constructor.prototype)[m]) ctor.prototype[m] = members[m]             else (function(m){                 // operate the memebers of child within the methods of super class                 var _super = function(self){ return function(){ return (zuper.prototype || zuper.constructor.prototype)[m].apply(self, arguments)} }                 var fnStr = members[m].toString()                     , idx = fnStr.indexOf('{') + 1                     , nFnStr = fnStr.substring(0, idx) + ';var zuper = _super(this);' + fnStr.substring(idx)                                  eval('ctor.prototype[m] = ' + nFnStr)             }(m))          // do shallow mixins         for(var mixin in mixins)             for(var m in mixins[mixin]) ctor.prototype[m] = mixins[mixin][m]          // additional methods         ctor._mixin = function(/*...mixins*/){             var mixins = arguments             for(var mixin in mixins)                 for(var m in mixins[mixin]) this.prototype[m] = mixins[mixin][m]         }          return ctor     }      /**      * @method defc.mixin      * @public      * @param {Any} obj - mixin target      * @param {...Object} mixins - mixin source      */     defc.mixin = function(obj/*, ...mixins*/){         var mixins = Array.prototype.slice.call(arguments, 1)         for(var mixin in mixins)             for(var m in mixins[mixin]) obj[m] = mixins[mixin][m]     } }))