But this `func_info_t` (rather than IID) is used for storing/creating the function object itself (like create_builtin_function but for proxies), not tied to any object, and such function object contains all the "code" of the function not just the signature, so isn't that actually more correct, idiomatically at least?
There is a difference between C/C++ and JS that we need to cover one way or another. C implementation is bound to a specific object type, which makes using `impl_from_*` possible. To keep that possibility in hooks, they need to be bound to a specific object type as well. More idiomatically: hooks are a part of C implementation of JS functions and C implementations are specific to object instance type.
There are no interfaces added to deal with prototype chains, unless you mean the new method I added for `func_info_t`?
Do you have a branch where I could see it in action?