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Comment by jashkenas | Hacker News Reader

In fact, they're both implemented in the same way, using the "standard" JavaScript pattern for setting up a prototype chain. (With a few minor extra features). Here's the annotated source code:

http://documentcloud.github.com/backbone/docs/backbone.html#...

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That's really what I liked the most about the Backbone implementation. It stays very close to the standard JS pattern--essentially mirroring what someone would do if they wanted to setup the prototype chain and attach methods manually.

It asks you to name the constructor method 'constructor' (when it could've easily been called something short like 'init' instead, for brevity). This corresponds well with the standard 'constructor' property available on each object, which points back to the constructor function that created the object.

The '__super__' property is also a nice convenience, without doing something "fancy" like wrapping each method with logic that temporarily injects a 'super' property into the current instance for the duration of a method call. Although that's definitely clever and convenient, I prefer the simplicity of using '__super__'.

Interestingly enough, the fancy approach for calling "super()" is actually prohibitively expensive ... making any method call in a subclass far slower than it otherwise could be. I don't think it's a viable option for a baseline library.

http://www.broofa.com/2009/02/javascript-inheritance-perform...

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