Two small object systems.

Miniobj.lua

Object={}Object.__index=Object
setmetatable(Object,Object)function Object:__call(...)return self:new(...)end
function Object:init()end
function Object:parent()return getmetatable(self)end
function Object:new(...)local e={}setmetatable(e,self)self.__index=self
e:init(...)return e
end

Miniobjl.lua

Object = {}
Object.__index = Object
setmetatable(Object, Object)

function Object:__call(...)
    return self:new(...)
end

function Object:init()
end

function Object:parent()
    return getmetatable(self)
end

function Object:new(...)
    local o = {}
    setmetatable(o, self)
    self.__index = self
    o:init(...)
    return o
end

Object.lua

Object = {}
Object.__index = Object
setmetatable(Object, Object)

-- Variables
Object.__metamethods =  {
    "__add", "__sub", "__mul", "__div", "__mod", "__pow", "__unm",
    "__len", "__lt", "__le", "__concat", "__tostring"
}

-- Metamethods
function Object:__call(...)
    return self:new(...)
end

function Object:__newindex(k, v)
    if k == "init"  and not rawget(self, __init) then
        rawset(self, "__init", v)
    elseif getfenv(2)[k] == self and not rawget(self, __init) then
        rawset(self, "__init", v)
    end
    
    rawset(self, k, v)
end

-- Constructor
function Object:__init()
end

-- Private/Static methods
function Object:__metamethod(event)
    return function(...)
        if self:parent() == self then
            error "Unimplemented metamethod called on object."
        end
        
        func = rawget(self, event)
        if func then
            return func(...)
        else
            return self:parent()[event](...)
        end
    end
end

-- Methods
function Object:parent()
    return getmetatable(self)
end

function Object:new(...)
    local o = {}
    setmetatable(o, self)
    self.__index = self
    self.__call = Object.__call
    self.__newindex = Object.__newindex
    
    for k,v in pairs(Object.__metamethods) do
        o[v] = self:__metamethod(v)
    end
    
    o:__init(...)
    return o
end