Javascript 继承静态和实例方法/属性 [英] Javascript inherit static and instance methods/properties
问题描述
在javascript中,我将如何设置继承以便静态和实例属性/方法被继承?
In javascript how would I set up inheritance so that static and instance properties/methods are inherited?
我的目标是构建一个基础类",第三方将从中继承,并且能够调用从基础类"继承的静态和实例属性/方法.
My goal is to build a base "class" that 3rd parties would inherit from, and be able to call static and instance properties/methods inherited from the base "class".
在我的示例中,我定义了一个配方基类,其他人可以从中继承并创建配方:
In my example I define a recipe base class that others can inherit from and create recipes off of:
Function.prototype.inherits = function (base) {
// code to inherit instance and static
// props/methods here
var temp = function () { };
temp.prototype = base.prototype;
this.prototype = new temp();
}
function Recipe() {
var self = this;
Recipe.ingredients = { };
Recipe.prepare = function (ingredients) {
// prepare each of the ingredients...
var preparedIngredients = ingredients;
Recipe.ingredients = preparedIngredients;
};
self.share = function () {
console.log('Recipe Shared!');
};
}
Toast.inherits(Recipe);
function Toast() {
var self = this;
}
var toast = new Toast();
// Child function should inherit static methods
Toast.Prepare({
bread: '2 slices',
butter: '1 knob',
jam: '1 tablespoon'
});
// Child function should inherit static properties
console.log(Toast.ingredients);
// Child function should inherit instance methods as well
toast.share();
// And if I define another it gets its own static properties/methods
// Spaghetti.ingredients !== Toast.ingredients
Spaghetti.inherits(Recipe);
function Spaghetti() {
var self = this;
}
Spaghetti.prepare({
noodles: '1 box',
tomatoes: 2,
sausage: 1
});
Plnkr 在这里:http://plnkr.co/edit/x8rKeKXSxDHMB4CD6j1c
推荐答案
你的继承是错误的,Toast 不是 Recipe 它有一个 Recipe.Recipe 的成分不能是静态的,因为 Recipe 可以用于烤面包、煎饼或许多其他菜肴.
Your inheritance is wrong, Toast is not a Recipe it has a Recipe. Ingredients of Recipe cannot be static because a Recipe can be used for toast, pancake or many other dishes.
function Recipe(name,ingredients) {
this.name=name;
this.ingredients = ingredients;
};
var Toast = function(){}
Toast.prototype.recipe = new Recipe('toast',{
bread: '2 slices',
butter: '1 knob',
jam: '1 tablespoon'
});
可以在此处找到有关原型的更多信息:https://stackoverflow.com/a/16063711/1641941
More info on prototype can be found here: https://stackoverflow.com/a/16063711/1641941
如果你想继承静态成员,你需要一个更好的例子:例如 MyDate 和 MyDateTime.
If you want to inherit static members you need a better example: for example MyDate and MyDateTime.
var MyDate=function(dateString){
this.date=(dateString)?new Date(dateString)
:new Date();
};
MyDate.YEAR=Date.prototype.getFullYear;
//... others like MONTH, DAY ...
MyDate.prototype.get = function(what){
if(what && typeof what==='function'){
return what.call(this.date);
}
console.log('nope');
};
var MyDateTime=function(dateString){
MyDate.call(this,dateString);
};
//set static properties (can write a function for this)
for(mystatic in MyDate){
if(MyDate.hasOwnProperty(mystatic)){
MyDateTime[mystatic]=MyDate[mystatic];
}
}
MyDateTime.HOUR=Date.prototype.getHours;
//instead of breaking encapsulation for inheritance
// maybe just use Object.create and polyfil if needed
// and stop reading DC when it comes to this subject
MyDateTime.prototype=Object.create(MyDate.prototype);
MyDateTime.prototype.constructor=MyDateTime;
var d = new MyDate();
console.log(d.get(MyDate.YEAR));
var dt = new MyDateTime();
console.log(dt.get(MyDateTime.YEAR));
console.log(dt.get(MyDateTime.HOUR));
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