How can I write extensions for Session without having to write separate methods for HttpSessionState and HttpSessionStateBase?

Question

I wrote the following extension methods for Session so that I can persist and retrieve objects by their type. This works well for my solution, but I ended up having to duplicate my extension methods to cover the old HttpSessionState and the new HttpSessionStateBase. I'd like to find a way to get these back down to one set that covers both types. Any thoughts?

public static class SessionExtensions
{
    #region HttpSessionStateBase

    public static T Get<T>(this HttpSessionStateBase session)
    {
        return session.Get<T>(typeof(T).Name);
    }

    public static T Get<T>( this HttpSessionStateBase session, string key )
    {
        var obj = session[key];

        if( obj == null || typeof(T).IsAssignableFrom( obj.GetType() ) )
            return (T) obj;

        throw new Exception( "Type '" + typeof( T ).Name + "' doesn't match the type of the object retreived ('" + obj.GetType().Name + "')." );
    }

    public static void Put<T>(this HttpSessionStateBase session, T obj, string key)
    {
        session[key] = obj;
    }

    public static void Put<T>(this HttpSessionStateBase session, T obj)
    {
        session.Put(obj, typeof(T).Name);
    }

    #endregion

    #region HttpSessionState

    public static T Get<T>( this HttpSessionState session )
    {
        return session.Get<T>( typeof( T ).Name );
    }

    public static T Get<T>( this HttpSessionState session, string key )
    {
        var obj = session[ key ];

        if( obj == null || typeof( T ).IsAssignableFrom( obj.GetType() ) )
            return ( T ) obj;

        throw new Exception( "Type '" + typeof( T ).Name + "' doesn't match the type of the object retreived ('" + obj.GetType().Name + "')." );
    }

    public static void Put<T>( this HttpSessionState session, T obj )
    {
        session.Put( obj, typeof(T).Name );
    }

    public static void Put<T>( this HttpSessionState session, T obj, string key )
    {
        session[ key ] = obj;
    }

    #endregion
}

Answer 1

You could keep your initial implementation and use HttpSessionStateWrapper to handle the HttpSessionState case:

SomeType t = new HttpSessionStateWrapper(SomeHttpSessionStateInstance)
    .Get<SomeType>();