LHF did mention that "This is totally different in nature from the introduction of _ENV.
While it was a simple, consistent solution, it did require some magic in the compiler: the creation of _ENV as an upvalue behind the scenes."
my question is: how much overhead in terms of bytecode space and speed does _ENV cost with respect to setfenv/getfenv?
from an historical perspective: why were getfenv/setfenv removed and substituted by _ENV? what was the advantage?
Andrea
