Using IronPython's 1.0.1 new community written built-in module support

In a previous post I mentioned the community written built-in modules support provided with IronPython 1.0.1. I remembered that Kevin Chu had posted a C# replacement for the CPython md5 library on the mailing list for inclusion in the IronPython core. His code is a perfect candiate for using the new external module loading support. So if you compile the code below as a library assembly

using System;
using System.Collections.Generic;
using System.Text;
using IronPython.Runtime;
using System.Security.Cryptography;
using System.Runtime.InteropServices;

[assembly: PythonModule("md5", typeof(IronPythonCommunity.Modules.PythonMD5))]
namespace IronPythonCommunity.Modules
{
   [PythonType("md5")]
   public class PythonMD5
   {
       private MD5 _provider;
       private readonly Encoding raw = Encoding.GetEncoding("iso-8859-1");
       private byte[] empty;

       public PythonMD5()
       {
           _provider = MD5.Create();
           empty = raw.GetBytes("");
       }

       public PythonMD5(string arg)
           : this()
       {
           this.Update(arg);
       }

       internal PythonMD5(MD5 provider)
           : this()
       {
           _provider = provider;
       }
       [PythonName("new")]
       public static PythonMD5
PythonNew([DefaultParameterValue(null)] string arg)
       {
           PythonMD5 obj;
           if (arg == null)
               obj = new PythonMD5();
           else
               obj = new PythonMD5(arg);
           return obj;
       }
       [PythonName("md5")]
       public static PythonMD5
PythonNew2([DefaultParameterValue(null)] string arg)
       {
           return PythonMD5.PythonNew(arg);
       }
       [PythonName("update")]
       public void Update(string arg)
       {
           byte[] bytes = raw.GetBytes(arg);
           _provider.TransformBlock(bytes, 0, bytes.Length, bytes, 0);
       }
       [PythonName("digest")]
       public string Digest()
       {
           _provider.TransformFinalBlock(empty, 0, 0);
           return raw.GetString(_provider.Hash);
       }
       [PythonName("hexdigest")]
       public string HexDigest()
       {
           _provider.TransformFinalBlock(empty, 0, 0);
           string hexString = "";
           foreach (byte b in empty)
           {
               hexString += b.ToString("X2");
           }
           return hexString;
       }
       [PythonName("copy")]
       public PythonMD5 Clone()
       {
           PythonMD5 obj = new PythonMD5(this._provider);
           return obj;
       }
   }
}

and create a DLLs directory in your IronPython 1.0.1 installation and copy the compiled assembly to it. When you start a new IronPython console, you be able to import md5 and use it like the CPython version.

>>> import md5
>>> md5
<module 'md5' (built-in)>
>>> m = md5.new()
>>> m.update("Nobody inspects")
>>> m.update(" the spammish repetition")
>>> m.digest()
u'\xbbd\x9c\x83\xdd\x1e\xa5\xc9\xd9\xde\xc9\xa1\x8d\xf0\xff\xe9'

Mind you, if you compare the code for the C# implementation with Seo Sanghyeon's md5.py you can see why using IronPython with .NET or Mono makes a programmers life easier.