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Dynamic prototyping support

As mentioned earlier, prototype chaining can’t be used in the true spirit of dynamic prototyping, which

is to keep all code for a class inside of its constructor. The zInherit library fixes this problem by allowing

the

inheritFrom()

method to be called from inside the constructor.

Take a look at the polygon dynamic prototyping example used earlier, now with the addition of the

zInherit library:

function Polygon(iSides) {

this.sides = iSides;

if (typeof Polygon._initialized == “undefined”) {

Polygon.prototype.getArea = function () {

return 0;

};

Polygon._initialized = true;

}

function Triangle(iBase, iHeight) {

Polygon.call(this, 3);

this.base = iBase;

this.height = iHeight;

if (typeof Triangle._initialized == “undefined”) {

Triangle.prototype.inheritFrom(Polygon);

Triangle.prototype.getArea = function () {

return 0.5 * this.base * this.height;

};

Triangle._initialized = true;

}

function Rectangle(iLength, iWidth) {

Polygon.call(this, 4);

this.length = iLength;

this.width = iWidth;

if (typeof Rectangle._initialized == “undefined”) {

Rectangle.prototype.inheritFrom(Polygon);

Rectangle.prototype.getArea = function () {

return this.length * this.width;

};

Rectangle._initialized = true;

}

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