Lua返回一个Closures函数实例

do
 function button(x)
  print("call button");
  x.action();
  print(x.label);
 end

 function add_to_display(digit)
  print("call add_to_display");
  print(digit);
 end

 function digitbutton(digit)
  return button{//return a table and the function(button), it means that the button receives the param(the table{...})
      label = tostring(digit),
      action = function()
         print("digit: ", digit);
         add_to_display(digit);
         end
       }

 end

 local fun = digitbutton(3);

end

写个简单的迭代器：

do
 t_ = {9, 2, 3, 4};

 function values(t)
  local i = 0;
  return function()
     i = i + 1;
     return t[i];
    end
 end

 iter = values(t_);

 while true do
  local element = iter();
  if element == nil then
   break;
  end

  print(element);
 end

end