Javascript模仿接口可以有三种方式：1.注释法 2.检查属性法 3.鸭式辨形法
1.注释法:此方法属于程序文档范畴，对接口的继承实现完全依靠程序员自觉
/* interface People{ function createHead(); function createBody(); } */ var woman = function(name){ //implements People interface this.name = name; } woman.prototype.showName = function(){ alert(this.name); } woman.prototype.createBody = function(){ //实现必要的方法 alert("身体已经创建好"); } woman.prototype.createHead = function(){ alert("头部已经创建好"); }
//2.属性检查法：把要实现的接口方法添加到类属性列表里，通过定义好的检测反复检查是否已经实现了那些方法
//优缺点：可以强迫程序员实现接口，没实现就报错。不过虽然声明了自己实现了哪些方法，但实现时很可能有遗漏
/* interface People{ function createHead(); function createBody(); } */ var woman = function(name){ this.name = name; this.implementsInterfaces = ['People']; } woman.prototype.showName = function(){ alert(this.name); } woman.prototype.createBody = function(){ //实现必要的方法 alert("身体已经创建好"); } woman.prototype.createHead = function(){ alert("头部已经创建好"); } function implement(obj,interfaces){ for(var i=1;i<interfaces.length;i++){ var interfaceName = interfaces[i]; var interfaceFound = false; for(var j=0;j<obj.implementsInterfaces.length;j++){ if(obj.implementsInterfaces[j] = interfaceName){ interfaceFound = true; break; } } if(!interfaceFound){ return false; } } return true; } function isImplememts(instance,interfaces){ //判断对象是否已经继承相应接口 if(!implement(instance,interfaces)){ throw new Error("Object doesn't implement a required interface"); } }
3.鸭式辨型法：（不通过外表判断鸭子，而通过其是否有鸭子的特性来判断。如James Whitcomb Riley所说，像鸭子一样走路并且嘎嘎叫的就是鸭子）
上面俩种都声明了自己实现了那些接口，其实声明不重要，实现接口核心的是类实现了接口方法集。如果类具有了接口定义的所有方法函数名相同的函数，那么认为它实现了接口
//接口类，用来创建接口 var Interface = function(name,motheds){ if(agruments.length!=2){ throw new Error("Interface constructor called with "+arguments.length+"arguments,but expected exactly 2"); } this.name = name; this.methods = []; for(var i=0;i<motheds.length;i++){ if(typeof motheds[i] !== 'string'){ throw new Error('Interface constructor expects mothed names to be'+'passes in as a string'); } this.methods.push(motheds[i]); } } Interface.prototype.ensureImplements = function(objs){ if(agruments.length != 1){ throw new Error("Interface constructor called with "+arguments.length+"arguments,but expected exactly 1") } for(var i=0;i<objs.length;i++){ var obj = objs[i]; for(var j=0;j<this.motheds.length;j++){ var mothed = this.methods[j]; if(!obj[mothed] || !typeof obj[mothed] !== 'function'){ throw new Error('Function Interface.ensureImplements:implements interface'+this.name+',obj.mothed'+mothed+'was not found'); } } } } //创建接口 var People = new Interface('People',['createHead','createBody']); //子类 var Woman = function(name){ this.name = name; this.implementsInterfaces = ['People']; } Woman.prototype.showName = function(){ alert(this.name); } Woman.prototype.createBody = function(){ //实现必要的方法 alert("女人身体已经创建好"); } Woman.prototype.createHead = function(){ alert("女人头部已经创建好"); } //子类 var Man = function(name){ this.name = name; this.implementsInterfaces = ['People']; } Man.prototype.showName = function(){ alert(this.name); } Man.prototype.createBody = function(){ //实现必要的方法 alert("男人身体已经创建好"); } Man.prototype.createHead = function(){ alert("男人头部已经创建好"); } //判断是否实现 Poeple.ensureImplements(['Woman','Man']);
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