With that said, I do not know why the cart is not updating as expected. I have just updated the extended cart class to CI 2.1.0 and had no problems getting the sample application to work. During the upgrade, the only things I changed were the parent call in the controller and the class itself. Maybe you could review my use of the class in the updated sample application and identify what you are doing differently?

When I change the constructor to:

function __construct()
{
parent::__construct();
}

Then the cart does not update and I get the same cart contents.

I am using CI 2.0.3
Do you have any solution for this?

The data in the included dump is not up to date. It has most of the geographic data, but I believe there have been some zips added since the data was collected.

Consider the Fibonacci sequence where f(n) = f(n – 1) + f(n – 2). Given n = 6 on the first call to the function, fib(5) and fib(4) will be calculated. However, fib(5) will also calculate fib(5-1), which has already been calculated by fib(6). That is wasted effort. If you run this script in Firebug, it will take a long time to complete or freeze/crash.

var fib = function(n) {
  if(n == 0 || n == 1) {
    return n;
  }

  return fib(n - 1) + fib(n - 2);
}

fib(100);

However, this snippet of code will run very quickly. The function is not amortized; it will run quickly on the first execution.

var computed = {};

var fib = function(n) {
  if(n == 0 || n == 1) {
    return n;
  }

  if(computed[n]) {
    return computed[n];
  }

  var val = fib(n - 1) + fib(n - 2);
  computed[n] = val;
  return val;
}

fib(100);

As for storing the look-up table in a more persistent location… that is definitely a possibility and a good idea depending on the context. I believe there is another term for this other than memoization, but I can’t think of it right now

It’s worth noting that the MY in MY_Cart must be uppercase. I spent a little time trying to figure out how codeigniter knows to load my custom library. Turns out it just magically knows as long as you get the name of the file and class correct.