Metaprogramming: An Introduction to JavaScript (ES6) Proxy

https://blog.greenroots.info/metaprogramming-an-introduction-to-javascriptes6-proxy-cjwkk64ly000gvds10db4l034

by atapas • 7 years ago

19 11 7 years ago

blog.greenroots.info

These make stack traces a pain in the ass to debug. This kind of magic is great for prototyping, but I'm very unconvinced it has a general purpose role in maintainable code.

codingvelocity• 7 years ago

You're quite correct. My team just inherited a large node codebase that had proxy sprinkled everywhere, complete with a custom undocumented dsl written using proxies. It was a nightmare to learn, hard to extend without breaking and resulted in quite a few refactoring sessions.

I think proxies have their place, but most apps don't need them imo

Waterluvian• 7 years ago

I've been using Immer which relies on proxies to give you a plain object interface but also copy on write immutability.

It's very nice and I think is a practical example of when proxies make sense. However it does at times suffer from the cost of doing magic: you handle them in unusual ways and suddenly they break a lot.

SomeOldThrow2• 7 years ago

Yea, you’re right, I can see that working in the right context. These ARE essentially DSLs, though, so their success largely depends on hard to define things like documentation, coupling, and quarantining to expected places.

kyriakos• 7 years ago

Looks like PHP magic methods for JavaScript.

quelltext2• 7 years ago

I wouldn't exactly call Proxies metaprogramming. It's not wrong but it's just not the best example of what metaprogramming is.

yvdriess• 7 years ago

Proxies trace back their origin in mirrors/mirages in metaprogramming for OO languages. (shoutout to AmbientTalk) It's a very Smalltalk way of doing reflection and intersection.

Do you mean that it lacks syntactic abstractions to be called metaprogramming?

quelltext2• 7 years ago

The author mentioned that metaprogramming is treating "code as data" which Proxies themselves don't really do.

atapas3• 7 years ago

If I understood correctly, The Reflection part of the Metaprogramming can be broken further into multiple parts like, - Introspection: Code is able to inspect itself - Self-Modification - Intercession: Acting behalf of somebody else

To me, Proxy is more into the category of 'Intercession', isn't it?

atapas3• 7 years ago

Awesome Discussions, Learned from it, Thanks!

Metaprogramming: An Introduction to JavaScript (ES6) Proxy

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