clsObject = { 
__ClassType = "class type" 
} 
                                                     
function clsObject:Inherit(o)   
  o = o or {} 
o.__ClassType = "class type" 
  o.mt = { __index = o} 
  setmetatable(o, {__index = self}) 
  return o 
end 
 
function clsObject:New(...) 
  local o = {} 
 
  setmetatable(o, self.mt) 
 
  if o.__init__ then 
    o:__init__(...) 
  end  
  return o 
end 
 
function clsObject:__init__() 
end 
 
function clsObject:Destroy() 
end 
 
function clsObject:GetType() 
  return "BaseClass" 
end 

function Super(TmpClass) 
  return getmetatable(TmpClass).__index 
end 
 
function IsSub(clsSub, clsAncestor) 
  local Temp = clsSub 
  while 1 do 
    local mt = getmetatable(Temp) 
    if mt then 
      Temp = mt.__index 
      if Temp == clsAncestor then 
        return true 
      end  
    else 
      return false 
    end  
  end  
end 

clsParent = clsObject:Inherit() 
 
function clsParent:Foo() 
  print("ParentFoo!") 
end 
 
local ParentObj = clsParent:New() 
ParentObj:Foo() 
 
 
clsSon = clsParent:Inherit() 
function clsSon:Foo() 
  Super(clsSon).Foo(self) 
  print("SonFoo") 
end 
 
local SonObj = clsSon:Inherit() 
SonObj:Foo() 
 
print(IsSub(clsSon, clsParent)) 
print(IsSub(clsSon, clsObject))