Lua multiple views solution

classes.lua

local classes = {}
local registry = {}

function classes.createClass(classname)
	local class = {}
	class.__views = {}
	registry[classname] = class
	return class
end

function classes.createInstance(classname)
	local class = registry[classname];
	local inst = {}
	local meta = {}
	meta.__index = function(inst, key) 
		return classes.indexClass(inst, class, key)
	end
	setmetatable(inst, meta)
	return inst
end

function classes.indexClass(inst, class, key)
	local view = getmetatable(inst).__view
	if view then
		local view = class.__views[view];
		if view[key] then
			return class[key]
		else
			error("not in view")
		end
	else
		return class[key]
	end
end

function classes.createView(classname, viewname)
	local class = registry[classname]
	local view = {}
	class.__views[viewname] = view
	return view
end

function classes.setInstanceView(instance, view)
	getmetatable(instance).__view = view
end

return classes

main.lua

local cls = require("classes")
local myClass = cls.createClass("MyClass")

function myClass:getInfo()
	print("MyClass:getInfo()")
	return self.info
end

function myClass:setInfo(value)
	print("MyClass:setInfo()")
	self.info = value
end

local publicView = cls.createView("MyClass", "public")
publicView.getInfo = true

local privateView = cls.createView("MyClass", "private")
privateView.getInfo = true
privateView.setInfo = true

local myInst = cls.createInstance("MyClass")
print("Without view:")
myInst:setInfo("hello world")
print(myInst:getInfo())

print()
print("With private view:")
cls.setInstanceView(myInst, "private")
myInst:setInfo("another world")
print(myInst:getInfo())

print()
print("With public view:")
cls.setInstanceView(myInst, "public")
myInst:setInfo("this will fail")
print("this should not print")