Simulating Lua states in Lua with only 250 lines of code

["Soni L." <fakedme@...>]

(Resending because someone said this was sent in HTML-only even tho I 
have my client set to send as both HTML and plaintext...)

https://github.com/SoniEx2/Stuff/blob/master/lua/Sandbox.lua

In C you can basically make multiple Lua states that are independent 
from eachother: they have their own globals (including global 
metatables, like the string metatable etc), their own registry? (idk), 
etc. This 250 LOC beast is slow as fuck and lets you do something 
similar enough that you can use it for sandboxing.

Why can't we get a way to make independent Lua states from Lua, anyway? 
(or rather with isolated registry and global metatables - this means the 
GC would be shared between them, thus allowing objects to be shared 
between them, but they wouldn't share the same global metatables or the 
same globals table) It would open up great possibilities! Not just 
sandboxing, but modularization and local monkeypatching (e.g. make your 
Lua module open a Lua state, then monkeypatch its string metatable etc 
so you can write your fancy monkeypatched code without breaking the code 
of ppl who use your module)

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