log.cs

using System.Linq;
using Umbraco.Core;
using Umbraco.Core.Composing;
using Umbraco.Core.Events;
using Umbraco.Core.Logging;
using Umbraco.Core.Services;
using Umbraco.Core.Services.Implement;

namespace MvcCourse.Core
{
    public class LetsLogComposer : IComposer
    {
        public void Compose(Composition composition)
        {
            composition.Components().Append<LetsLogComponent>();
        }
    }

    public class LetsLogComponent : IComponent
    {
        private readonly ILogger _logger;

        public LetsLogComponent(ILogger logger)
        {
            _logger = logger;
        }

        public void Initialize()
        {
            ContentService.Published += ContentService_Published;
        }

        private void ContentService_Published(IContentService sender, ContentPublishedEventArgs e)
        {
            _logger.Info<LetsLogComponent>($"You just published {e.PublishedEntities.Count()} item(s)!");
        }

        public void Terminate() { }
    }
}