StaticSingletonHelper.cs

/// <summary>
/// Provides a way to override the current <see cref="implementation"/>.
/// </summary>
/// <param name="valueFactory">Factory that creates the new implementation</param>
/// <param name="implementation">Reference to the current implementation, it will be
///  updated with the new <see cref="valueFactory"/>.</param>
/// <param name="lazyLoad">Set to true if you want to lazy load your new implementation
/// (not recommended if your implementation listens for events in it's constructor).</param>
public static void OverrideDefault<TInterface>(Func<TInterface> valueFactory, ref Lazy<TInterface> implementation, bool lazyLoad = false)
{
    if (implementation.IsValueCreated)
    {
        // ReSharper disable once SuspiciousTypeConversion.Global
        var oldImpl = implementation.Value as INeedToUnSubscribeFromEvents;
        oldImpl?.UnSubscribeFromEvents();
    }

    implementation = new Lazy<TInterface>(valueFactory, LazyThreadSafetyMode.ExecutionAndPublication);

    if (!lazyLoad)
    {
        Current.Touch();
    }
}