Decorator Pattern extend()

[iramirezc]

Hi Addy,

I wonder why in this line of code

essential-js-design-patterns/book/snippets/01-JavaScript-Design-Patterns/12-the-decoration-pattern.es5.js

Line 255 in 21346c1

extend( CaseDecorator, MacbookDecorator );

we are extending CaseDecorator with MacbookDecorator. As functions, they don't have any enumerable properties by their own yet. Shouldn't happen the extension in the prototype like:

extend(CaseDecorator.prototype, MacbookDecorator.prototype);

because trying to do this console.log(decoratedMacbookPro.addEngraving()); results in a TypeError: decoratedMacbookPro.addEngraving is not a function

[iramirezc]

Also, in this constructor:

essential-js-design-patterns/book/snippets/01-JavaScript-Design-Patterns/12-the-decoration-pattern.es5.js

Line 249 in 21346c1

var CaseDecorator = function( macbook ){

shouldn't CaseDecorator be a "subclass" of MacbookDecorator as we learned from the Mixins Pattern:

var CaseDecorator = function( macbook ){
   MacbookDecorator.call(this, macbook)
};

That way, when doing

essential-js-design-patterns/book/snippets/01-JavaScript-Design-Patterns/12-the-decoration-pattern.es5.js

Line 274 in 21346c1

var decoratedMacbookPro = new CaseDecorator( myMacbookPro );

we are ensuring that the MacbookPro instance fulfills the required interface.