Example of a Unity Interceptor.

ProfilingInterceptionBehavior.cs

public class ProfilingInterceptionBehavior : IInterceptionBehavior
{
    [Dependency]
    public ILog Log { get; set; }
        
	public IMethodReturn Invoke(IMethodInvocation input,
        GetNextInterceptionBehaviorDelegate getNext)
    {
        // Code here will execute prior to the method that was called.
        // Add any custom code you want to execute prior to intercepted method here.

        // Invoke the next behavior in the chain.
        var result = getNext()(input, getNext);

        // Code here will execute after the method that was called.
        // Add any custom code you want to execute after the intercepted method here.
        if (result.Exception != null)
        {
            WriteLog(String.Format(
              "Method {0} threw exception {1}.",
              input.MethodBase, result.Exception.Message));
        }

        return result;
    }

    public IEnumerable<Type> GetRequiredInterfaces()
    {
        return Type.EmptyTypes;
    }

    public bool WillExecute
    {
        get { return true; }
    }

    private void WriteLog(string message)
    {
        if (Log != null)
        {
            Log.DebugFormat("Profiler: {0}", message);
        }
    }
}