"Assign by reference"-like behavior in Lua

ref.lua

ref=(function(obj,key)
return (function(...)
local p={...}
if select('#',...)==0 then
return obj[key]
else
obj[key]=p[1]
end
end)
end)

ghost = {boo = true}
boo = ref(ghost,'boo')
boo(nil)
print(boo())
print(ghost.boo)
print(boo())