javascript 在javascript中声明受保护的变量
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declaring protected variable in javascript
提问by indianwebdevil
How do i declare protected variable. Let me give an example here
我如何声明受保护的变量。让我在这里举个例子
// Constructor
function Car(){
// Private Variable
var model;
}
// Public variable
Car.prototype.price = "5 Lakhs";
// Subtype
function Indiancar(){
}
// Prototype chaining
Indiancar.prototype = new Car();
// Instantiating Superclass object
var c = new Car();
// Instantiating subclass object
var ic = new Indiancar();
in this I would like to have a variable that is accessible as ic.variabl that is also present in car class.
在这方面，我希望有一个可作为 ic.variabl 访问的变量，该变量也存在于汽车类中。
回答by Tejs
You would do something like this:
你会做这样的事情：
var Base = function()
{
var somePrivateVariable = 'Hello World';
this.GetVariable = function()
{
return somePrivateVariable;
};
this.SetVariable = function(newText)
{
somePrivateVariable = newText;
};
};
var Derived = function()
{
};
Derived.prototype = new Base();
var instance = new Derived();
alert(instance.GetVariable());
instance.SetVariable('SomethingElse');
alert(instance.GetVariable());
Assuming I understood your question correctly.
假设我正确理解了你的问题。
EDIT: Updating with true 'private' variable.
编辑：使用真正的“私有”变量进行更新。
回答by slobo
There is a way to define protected variables in JavaScript:
有一种方法可以在 JavaScript 中定义受保护的变量：
A constructor function in javascript may return any object (not necesserily this). One could create a constructor function, that returns a proxy object, that contains proxy methods to the "real" methods of the "real" instance object. This may sound complicated, but it is not; here is a code snippet:
javascript 中的构造函数可以返回任何对象（不一定是this）。可以创建一个构造函数，它返回一个代理对象，该对象包含“真实”实例对象的“真实”方法的代理方法。这听起来可能很复杂，但事实并非如此；这是一个代码片段：
var MyClass = function() {
var instanceObj = this;
var proxyObj = {
myPublicMethod: function() {
return instanceObj.myPublicMethod.apply(instanceObj, arguments);
}
}
return proxyObj;
};
MyClass.prototype = {
_myPrivateMethod: function() {
...
},
myPublicMethod: function() {
...
}
};
The nice thing is that the proxy creation can be automated, if we define a convention for naming the protected methods. I created a little library that does exactly this: http://idya.github.com/oolib/
好处是代理创建可以自动化，如果我们定义命名受保护方法的约定。我创建了一个小库，它就是这样做的：http: //idya.github.com/oolib/
