import(io) -- localize all string-key values in the io table
Even if it were possible, I don't think this is a good idea. It would encourage people to dump unnecessary locals into their scripts -- inflating the generated byte code for no terribly good reason. When reading a script, programmers wouldn't be able to tell whether a given "global" was actually global, or was being shadowed by an implicitly added local.
I want to create locals in batch and not simply modify the _ENV to "pass through" to the 'table' table (hah). Sometimes modifying _ENV is not an option or is just ~inappropriate~.
If what you want is convenience, there's any number of neat _ENV tricks than can help here. For example, if you don't want to pass definitions through to the original table, you can do something like:
local _ENV = setmetatable({env=_ENV},{__index=_ENV})
But if what you're after is efficiency, I suspect wildcard localizing would hurt more than it helps.
-Sven