[Izkata]

> I mean if you really need super strong isolation, you can always create a copy of the library object; metaprogramming, dynamic classes, etc, all make it really easy to even, say, create a duplicate class object with references to the original method implementations. Or decorated ones. Or countless other approaches.

> My point isn't that I don't see problems that could be solved by this; my point is that I can't think of any problems that this solves, that wouldn't be better solved by things that don't do any innards-fiddling in what is arguably the most sharply-edged part of python: packaging and imports.

All these examples have the dependency order wrong, and you're right on those - it's simpler to wrap them somehow. But this is doing something different, that is either much harder or outright impossible with those methods: Tweaking something internal to the module while leaving its interface alone. This is shown in both their examples where they modify the TextWrapper object but then use it through the library's wrap() function, and modify the Session object but then just use the standard get() interface to requests.

[nbadg]

In that case I'd opt for dynamic module creation using metaprogramming instead of an import hook. And I personally would argue that grabbing the code objects from module members and re-execing them into a new module object to re-bind their globals is simpler than an AST transformation.

But regardless of the transformation methodology: the import hook itself is just a delivery mechanism for the modified code. There's nothing stopping the library from using the same transformation mechanism but accessing it with dynamic programming techniques instead of an import hook. And there's nothing you can't do that way.