function class(constructor)
    namespace = {}
    namespace.__index = namespace
    namespace.new = function(...)
        local outerSelf = self
        -- aliases
        local this = {}
        self = this
        -- finish
        setmetatable(this,namespace)
        constructor(unpack(arg))
        self = outerSelf -- used to allow constructors inside constructors
        return this
    end
    return namespace
end

-- I COULD MAKE class(namespace,extend,constructor) but new function name is clearer
function classExtends(extend,constructor)
    namespace = {}
    namespace.__index = namespace
    namespace.new = function(...)
        local outerSelf = self
        -- aliases
        local this = extend.new()
        self = this
        -- finish
        setmetatable(this,namespace)
        constructor(unpack(arg))
        self = outerSelf -- used to allow constructors inside constructors
        return this
    end
    return namespace
end

----------
-- TEST --
----------
Test = class(function()
    self.a = 1
    self.b = 3

    function self:set_a(new_a)
        self.a = new_a
    end
end)

App = classExtends(Test, function(c)
    print(self.a, self.b, c)
end)

local o = App.new(6)
o:set_a(2)
print(o.a)
App.new(7)