--
-- $Header: /Users/dap/lua/RCS/OO.lua,v 1.4 2007/02/11 09:53:01 dap Exp $
--
-- Author (a) 2007, Damon Anton Permezel.  All bugs revered.
--
-- Object Oriented Package for Lua
--

module(..., package.seeall)

function class(o)
   local cls = o or {}

   function cls:subclass(o, ...)
      local super = self
      local new_class = super:new(o, ...)

      function new_class:class()
	 return new_class
      end
      function new_class:super()
	 return super:class()
      end

      function new_class:init(...)
	 --
	 -- important to use the current definition of super
	 -- (ok: we have it here, but this is for doco)
	 --
	 new_class:super().init(self, ...)
      end

      return new_class
   end

   -- return the class object of the instance
   function cls.class()
      return cls
   end

   -- return the super class object of the instance
   function cls.super()
      return nil
   end
   
   local function new(self, o, ...)
      self.__index = self
      self = setmetatable(o or {}, self)
      self:init(...)
      return self
   end
   cls.new  = cls.new  or new

   local function init(self, ...)
   end
   cls.init = cls.init or init
   
   local function copy(self, ...)
      local new = self:new(unpack(arg))
      for n,v in pairs(self) do new[n] = v end
      return new
   end
   cls.copy = cls.copy or copy

   -- return true if the caller is an instance of class
   function cls:isa(class)
      local cur_class = cls

      while cur_class do
	 if cur_class == class then
	    return true
	 else
	    cur_class = cur_class:super()
	 end
      end

      return false
   end

   return cls
end