confusing behaviour of environments for lua > 5.2 about sol2

[lceWolf]

http://lua-users.org/wiki/EnvironmentsTutorial confirms that the _ENV table is changed for everything in the current chunk

When loading a chunk, the top-level function gets a new _ENV upvalue, and any nested functions inside it can see it. You can pretend that when loading works something like this:

local _ENV = _G
return function (...) -- this function is what's returned from load
-- code you passed to load goes here, with all global variable names replaced with _ENV lookups
-- so, for example "a = b" becomes "_ENV.a = _ENV.b" if neither a nor b were declared local
end
Now you can see that _ENV is an ordinary local variable, how all the functions have access to the _ENV, and why if one function changes _ENV all other functions in the loaded chunks will see the change. That's why if you want a function to only change its own environment, you need to make a new _ENV local that shadows the original one.