gistfile1.lua

class = {}

class['@instance_protocol'] = {
  -- Dispatch instance methods
  __index= function(instance, member) end
}


class['@protocol'] = {
  class = class,

  -- Instantiation
  __call = function(class_obj, ...) end,

  -- Dispatch class methods
  __index = class['@instance_protocol'].__index
}

function class.constructor(self, prototype)
end

class.prototype = {
  is_domain_of = function(self, instance)
      local metatable = getmetatable(instance)
      if metatable then
        return metatable.class == self
      else
        return false
      end
  end;
  
  subclass = function(superclass, prototype)
    -- Missing constructor 
    if not (prototype[1] and type(prototype[1]) == 'function') then
      prototype[1] = superclass.constructor
    end
    
    local classobj = class(prototype)
    
    -- set superclass on classobj metatable, what about instance metatable
    local protocol = table.merge(
      getmetatable(classobj), { superclass = superclass }
    )
    setmetatable(classobj, protocol)
    classobj.prototype.super = superclass.constructor

    return classobj
  end;
}

setmetatable(class, class['@protocol'])



----- example
do -- test inhieritance
  local mammal = class {
    function(self, name)
      self.name = name
      self.body_features = {'hair', 'heart', 'teeth'}
    end;
    
    talk = function(self)
      print 'i am a mammal'
    end;
  }
  
  local pet = mammal.subclass {
    function(self, ...)
      self.name, self.owner = ...
      self.super(self.name)
    end;
    
    eat = function(self) 
      print 'feeting the pet' 
    end;
  }

  local mydog = pet('bobo', 'taylor luk')

  print(mydog.body_features)
  mydog.eat()
end