CODEWITHSUNDEEP
javascriptgoogle-closure-compilergoogle-closure
FrancescoA
FrancescoA

Reputation: 131

Google closure compiler: How to do inheritance when using a factory

Say I have a class Car.

/**
 *
 * @constructor
 * @extends {Component}
 */
obj.Car = function(prop1, prop2) {
    goog.base(this, prop1);

    this.prop2 = prop2;
};

goog.inherits(obj.Car, Component);

/**
 * 
 * @return {obj.Car}
 */
obj.Car.create = function(a,b,c) {
    var prop1 = obj.Car.createProp1(a,b,c);
    var prop2 = obj.Car.createProp2(a,b,c);
    return new obj.Car(prop1, prop2);
 }

Cool. Now I want to sublcass car. Call it SuperCar. 

obj.SuperCar = function(prop1,prop2) {
    goog.base(this, prop1, prop2);
};
goog.inherits(obj.SuperCar, obj.Car);

How do I write the factory create method for SuperCar so that another class can also extend SuperCar?

So, ideally:

/**
 * @return {obj.SuperCar} 
 */
obj.SuperCar.create() = function() {
    return /** type {obj.SuperCar} */ Obj.Car.create.apply(this, arguments);
};

However, this means I have to change obj.Car to:

/**
 * @this {*) ????????? only this works
 * @return {obj.Car}
 */
obj.Car.create = function(a,b,c) {
    var prop1 = obj.Car.createProp1(a,b,c);
    var prop2 = obj.Car.createProp2(a,b,c);
    return new this(prop1, prop2);
};

This Javascript actually runs uncompiled and compiles. But I get a TypeError when running it compiled. Does anyone know the best solution for this? I've tried a few thing but can't seem to get it right.

Upvotes: 2

Views: 511

Answers (1)

Hatem Mostafa
Hatem Mostafa

Reputation: 85

I will assume that this is the base class.

SuperCar.js

/**
 * @constructor
 */
obj.SuperCar = function() {
};

/**
 * @return {obj.SuperCar}
 */
obj.SuperCar.create = function() {
   return new obj.SuperCar();
}

Car.js

/**
 * @param {*} prop1
 * @constructor
 * @extends {obj.SuperCar}
 */
obj.Car = function(prop1) {
    goog.base(this);

    this.prop1 = prop1;
};
goog.inherits(obj.Car, obj.SuperCar);

/**
 * @param {*} prop1
 * @return {obj.Car}
 * @override
 */
obj.SuperCar.create = function(prop1) {
   return new obj.Car(prop1);
}

Normally if you are going to override a function you can use /** @inheritDoc */ annotation or if you are going to change the function definition then write the new function definition and add the @override annotation.

Upvotes: 1

Related Questions