mef

I recently started using Lazy throughout my application, and I was wondering if there are any obvious negative aspects that I need to take into account when using Lazy<T> ? I am trying to utilize Lazy<T> as often as I deem it appropriate, primarily to help reduce the memory footprint of our loaded, but inactive plugins. I'll expand a bit on my comment, which reads: I've just started using Lazy, and find that it's often indicative of bad design; or laziness on the part of the programmer. Also, one disadvantage is that you have to be more vigilant with scoped up variables, and create proper

I have IMessageSender interface. using System.ComponentModel.Composition; public interface IMessageSender { void Send(string message); } And I have two plugins that implements this interface. This is plugin.cs. using System.ComponentModel.Composition; using System.ComponentModel.Composition.Hosting; using System.Reflection; using System; [Export(typeof(IMessageSender))] public class EmailSender : IMessageSender { public void Send(string message) { Console.WriteLine(message); } } and this is plugin2.cs [Export(typeof(IMessageSender))] public class EmailSender : IMessageSender { public void Send

I'm using MEF to load plugins in my app. Everything works, but I want new parts to be discovered when they are dropped into my app folder. Is this possible? DirectoryCatalog has a Changed event but I'm not sure how it works. This is my code right now: public sealed class RevealerFactory { private static readonly Lazy<RevealerFactory> lazy = new Lazy<RevealerFactory>(() => new RevealerFactory()); public static RevealerFactory Instance { get { return lazy.Value; } } private FileSystemWatcher watcher; private RevealerFactory() { Initialize(); } [ImportMany(RequiredCreationPolicy = CreationPolicy

Is it possible to intercept dependency requests in MEF before they get handled by MEF? This would be useful for implementing decorators and advanced lifetime management. Something like... catalogue.AddInterceptor<IExpensiveService>(b => ... return from pool ...); Or even... catalogue.AddInterceptor<IExpensiveService>(b => new Decorator(b())); (where 'b' is the underlying MEF resolution func for resolving the service) Not out of the box, but you can write your own ExportProvider or ComposablePartCatalog implementation to do this. MefContrib appears to have implemented something like that, take

I have set up an assembly catalog: private CompositionContainer GetContainer() { // initialize directory info ExtensionDirectory = new DirectoryInfo(settings.ExtensionsPath); // directory catalog var dirCatalog = new DirectoryCatalog(ExtensionDirectory.FullName); return new CompositionContainer(dirCatalog); } The contents of the container will load up all the assemblies in the directory as expected. I do not want to actually compose anything yet because I have constructors that will be injected with dependencies. What I want to do is use the AssemblyCatalog as a repository; query for a

I'm using MEF to add plugins to our DAL which is used by our WebApp. This works fine, but when our service layer references the DAL, it's looking for plugins in \ServiceLayer\Plugins\ rather than \WebSite\Plugins\ (which makes sense are we're using a relative path. {DirectoryCatalog (Path="plugins/")}. The problem is if we use an absolute path it refuses to load the plugins from both the SL and the DAL, which I believe is because the path isn't within the same directory or subdiectory of the App loading the plugins(?). How can I get them to both load plugins from one folder? Thanks You can't