[chubot]

Thanks for the response, but I wouldn't call that empirical support for prototypes. They took JIT technology developed for Self and applied it to a class-based language, Java. That doesn't mean that prototypes are good for writing programs. It actually indicates the opposite, because the technology in Self that ended up actually being deployed turned out to be something else.

(I also worked at Google and am somewhat familiar with the Self to HotSpot to v8 heritage.)

Your second paragraph is exactly what I think is wrong with prototypes. There's not enough structure, and not enough constraint. Constraints are useful for reasoning about programs. You might as well just have a bunch of structs and function pointers (and certainly many successful programs are written that way).

Having every application roll its own class system is a terrible idea, in theory and in practice. In practice JavaScript programs end up with multiple class systems because of this. The Lua ecosystem also has this problem.

It's analogous to every library in C rolling their own event loop or thread pool, leading to a fragmenetation of concurrency approaches. Go and node.js both unify the approach to concurrency so every application doesn't end up with 3 different concurrency abstractions.

I don't buy your 3rd paragraph. Python is class-based; it has the characteristic you're talking about with respect to a small team of hackers; and that has been empirically supported by hundreds or thousands of startups being acquired (Instagram, etc.) and even huge companies created (Dropbox).

I honestly think prototypes have failed in the marketplace of ideas and there's a good reason for that. I use metaclasses all the time but not for dynamically changing sets of methods. That seems like a horrible idea. The way I use them is for generating types from external sources like CSV/SQL/protobuf schemas.

[nostrademons]

Python has metaclasses, and they're used extensively in many of the frameworks that were critical for those startups (Django etc.). They're coming to Javascript too, in the form of ES6 proxies, which have been long awaited.

I actually think metaclasses are probably a better solution than prototypes, because they let you write the majority of your code in a class-based style and only incorporate funky abstractions when they're really necessary, which is typically infrequently. My point is that prototypes are strictly more powerful than (non-metaclass) class-based systems, and that this power lets you build powerful abstractions that can dramatically decrease the number of lines of code you need to write for an initial system.