Middleclass

local middleclass = {   _VERSION     = 'middleclass v3.0.1',   _DESCRIPTION = 'Object Orientation for Lua',   _URL         = 'https://github.com/kikito/middleclass',   _LICENSE     = [[     MIT LICENSE      Copyright (c) 2011 Enrique García Cota      Permission is hereby granted, free of charge, to any person obtaining a     copy of this software and associated documentation files (the     "Software"), to deal in the Software without restriction, including     without limitation the rights to use, copy, modify, merge, publish,     distribute, sublicense, and/or sell copies of the Software, and to     permit persons to whom the Software is furnished to do so, subject to     the following conditions:      The above copyright notice and this permission notice shall be included     in all copies or substantial portions of the Software.      THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS     OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF     MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.     IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY     CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,     TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE     SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.   ]] }  local function _setClassDictionariesMetatables(aClass)   local dict = aClass.__instanceDict   dict.__index = dict    local super = aClass.super   if super then     local superStatic = super.static     setmetatable(dict, super.__instanceDict)     setmetatable(aClass.static, { __index = function(_,k) return dict[k] or superStatic[k] end })   else     setmetatable(aClass.static, { __index = function(_,k) return dict[k] end })   end end  local function _setClassMetatable(aClass)   setmetatable(aClass, {     __tostring = function() return "class " .. aClass.name end,     __index    = aClass.static,     __newindex = aClass.__instanceDict,     __call     = function(self, ...) return self:new(...) end   }) end  local function _createClass(name, super)   local aClass = { name = name, super = super, static = {}, __mixins = {}, __instanceDict={} }   aClass.subclasses = setmetatable({}, {__mode = "k"})    _setClassDictionariesMetatables(aClass)   _setClassMetatable(aClass)    return aClass end  local function _createLookupMetamethod(aClass, name)   return function(...)     local method = aClass.super[name]     assert( type(method)=='function', tostring(aClass) .. " doesn't implement metamethod '" .. name .. "'" )     return method(...)   end end  local function _setClassMetamethods(aClass)   for _,m in ipairs(aClass.__metamethods) do     aClass[m]= _createLookupMetamethod(aClass, m)   end end  local function _setDefaultInitializeMethod(aClass, super)   aClass.initialize = function(instance, ...)     return super.initialize(instance, ...)   end end  local function _includeMixin(aClass, mixin)   assert(type(mixin)=='table', "mixin must be a table")   for name,method in pairs(mixin) do     if name ~= "included" and name ~= "static" then aClass[name] = method end   end   if mixin.static then     for name,method in pairs(mixin.static) do       aClass.static[name] = method     end   end   if type(mixin.included)=="function" then mixin:included(aClass) end   aClass.__mixins[mixin] = true end  local Object = _createClass("Object", nil)  Object.static.__metamethods = { '__add', '__call', '__concat', '__div', '__ipairs', '__le',                                 '__len', '__lt', '__mod', '__mul', '__pairs', '__pow', '__sub',                                 '__tostring', '__unm'}  function Object.static:allocate()   assert(type(self) == 'table', "Make sure that you are using 'Class:allocate' instead of 'Class.allocate'")   return setmetatable({ class = self }, self.__instanceDict) end  function Object.static:new(...)   local instance = self:allocate()   instance:initialize(...)   return instance end  function Object.static:subclass(name)   assert(type(self) == 'table', "Make sure that you are using 'Class:subclass' instead of 'Class.subclass'")   assert(type(name) == "string", "You must provide a name(string) for your class")    local subclass = _createClass(name, self)   _setClassMetamethods(subclass)   _setDefaultInitializeMethod(subclass, self)   self.subclasses[subclass] = true   self:subclassed(subclass)    return subclass end  function Object.static:subclassed(other) end  function Object.static:isSubclassOf(other)   return type(other)                   == 'table' and          type(self)                    == 'table' and          type(self.super)              == 'table' and          ( self.super == other or            type(self.super.isSubclassOf) == 'function' and            self.super:isSubclassOf(other)          ) end  function Object.static:include( ... )   assert(type(self) == 'table', "Make sure you that you are using 'Class:include' instead of 'Class.include'")   for _,mixin in ipairs({...}) do _includeMixin(self, mixin) end   return self end  function Object.static:includes(mixin)   return type(mixin)          == 'table' and          type(self)           == 'table' and          type(self.__mixins)  == 'table' and          ( self.__mixins[mixin] or            type(self.super)           == 'table' and            type(self.super.includes)  == 'function' and            self.super:includes(mixin)          ) end  function Object:initialize() end  function Object:__tostring() return "instance of " .. tostring(self.class) end  function Object:isInstanceOf(aClass)   return type(self)                == 'table' and          type(self.class)          == 'table' and          type(aClass)              == 'table' and          ( aClass == self.class or            type(aClass.isSubclassOf) == 'function' and            self.class:isSubclassOf(aClass)          ) end    function middleclass.class(name, super, ...)   super = super or Object   return super:subclass(name, ...) end  middleclass.Object = Object  setmetatable(middleclass, { __call = function(_, ...) return middleclass.class(...) end })  return middleclass