Code Sample 2 (factory pattern)

CodeSample2.cs

/* ***
 * This sample is again from an ORM tool that I had been working on.
 *
 * This is simply an example of a "factory" pattern that I wrote a few years ago.
 * This factory is designed to return the same IDataBinder instance when the same
 * database connection string is passed in.
 * *** */



/// <summary>
/// Creates instances of Data Binders.
/// Each data binder should be treated as a singleton per connection
/// for caching purposes. This factory handles that relationship.
/// </summary>
internal sealed class DataBinderFactory
{
    private static Dictionary<string, Dictionary<string, IDataBinder>> dataBinders = new Dictionary<string, Dictionary<string, IDataBinder>>();

    /// <summary>
    /// Get a data binder instance associated with the gives connection string.
    /// </summary>
    /// <param name="dbConnectionString">The connection string that the data binder is associated with.</param>
    /// <param name="dataBinderName">The full type name of the data binder.</param>
    /// <returns>An instance of the Data Binder.</returns>
    internal static IDataBinder GetDataBinder(string dbConnectionString, string dataBinderName)
    {
        // first check for an existing data binder instance.
        if(dataBinders.ContainsKey(dbConnectionString))
        {
            var bindersByName = dataBinders[dbConnectionString];
            if (bindersByName.ContainsKey(dataBinderName))
            {
                return bindersByName[dataBinderName];
            }
        }

        // if no existing instance found, then we need to create one.
        return CreateDataBinder(dbConnectionString, dataBinderName);
    }

    /// <summary>
    /// Removes cached data binders associated with the given connection string.
    /// </summary>
    /// <param name="dbConnectionString"></param>
    internal static void ClearDataBinders(string dbConnectionString)
    {
        if(dataBinders.ContainsKey(dbConnectionString))
        {
            dataBinders[dbConnectionString].Clear();
            dataBinders.Remove(dbConnectionString);
        }
    }

    /// <summary>
    /// Removes all cached data binders.
    /// </summary>
    internal static void ClearDataBinders()
    {
        var binderEnum = dataBinders.GetEnumerator();
        while (binderEnum.MoveNext())
            binderEnum.Current.Value.Clear();
        dataBinders.Clear();
    }

    private static IDataBinder CreateDataBinder(string dbConnectionString, string dataBinderName)
    {
        lock (dataBinders)
        {
            if (dataBinders.ContainsKey(dbConnectionString) && dataBinders[dbConnectionString].ContainsKey(dataBinderName))
                return dataBinders[dbConnectionString][dataBinderName];
            try
            {
                IDataBinder newBinder = (IDataBinder)(Activator.CreateInstance(Type.GetType(dataBinderName)));
                if (!dataBinders.ContainsKey(dbConnectionString))
                    dataBinders.Add(dbConnectionString, new Dictionary<string, IDataBinder>());
                Dictionary<string, IDataBinder> bindersByName = dataBinders[dbConnectionString];
                bindersByName.Add(dataBinderName, newBinder);
                return newBinder;
            }
            catch (Exception e)
            {
                throw new StormConfigurationException("Unable to create an instance of Data Binder with type [" + dataBinderName + "].", e);
            }
        }
    }
}