Javascript模仿接口可以有三種方式：1.注釋法 2.檢查屬性法 3.鴨式辨形法
1.注釋法:此方法屬於程序文檔范疇，對接口的繼承實現完全依靠程序員自覺
/*
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(){ //實現必要的方法
alert("身體已經創建好");
}
woman.prototype.createHead = function(){
alert("頭部已經創建好");
}
//2.屬性檢查法：把要實現的接口方法添加到類屬性列表裡，通過定義好的檢測反復檢查是否已經實現了那些方法
//優缺點：可以強迫程序員實現接口，沒實現就報錯。不過雖然聲明了自己實現了哪些方法，但實現時很可能有遺漏
/*
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(){ //實現必要的方法
alert("身體已經創建好");
}
woman.prototype.createHead = function(){
alert("頭部已經創建好");
}
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){ //判斷對象是否已經繼承相應接口
if(!implement(instance,interfaces)){
throw new Error("Object doesn't implement a required interface");
}
}
3.鴨式辨型法：（不通過外表判斷鴨子，而通過其是否有鴨子的特性來判斷。如James Whitcomb Riley所說，像鴨子一樣走路並且嘎嘎叫的就是鴨子）
上面倆種都聲明了自己實現了那些接口，其實聲明不重要，實現接口核心的是類實現了接口方法集。如果類具有了接口定義的所有方法函數名相同的函數，那麼認為它實現了接口
//接口類，用來創建接口
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');
}
}
}
}
//創建接口
var People = new Interface('People',['createHead','createBody']);
//子類
var Woman = function(name){
this.name = name;
this.implementsInterfaces = ['People'];
}
Woman.prototype.showName = function(){
alert(this.name);
}
Woman.prototype.createBody = function(){ //實現必要的方法
alert("女人身體已經創建好");
}
Woman.prototype.createHead = function(){
alert("女人頭部已經創建好");
}
//子類
var Man = function(name){
this.name = name;
this.implementsInterfaces = ['People'];
}
Man.prototype.showName = function(){
alert(this.name);
}
Man.prototype.createBody = function(){ //實現必要的方法
alert("男人身體已經創建好");
}
Man.prototype.createHead = function(){
alert("男人頭部已經創建好");
}
//判斷是否實現
Poeple.ensureImplements(['Woman','Man']);