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POMEF + SL4 question
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copied!<p>I'm working on an app in the Silverlight 4 RC and i'm taking the oppertunity to learn MEF for handling plugin controls. I've got it working in a pretty basic manor, but it's not exactly tidy and I know there is a better way of importing multiple xap's.</p> <p>Essentially, in the App.xaml of my host app, I've got the following telling MEF to load my xap's:</p> <pre><code>AggregateCatalog catalog = new AggregateCatalog(); DeploymentCatalog c1 = new DeploymentCatalog(new Uri("TestPlugInA.xap", UriKind.Relative)); DeploymentCatalog c2 = new DeploymentCatalog(new Uri("TestPlugInB.xap", UriKind.Relative)); catalog.Catalogs.Add(c1); catalog.Catalogs.Add(c2); CompositionHost.Initialize(catalog); c1.DownloadAsync(); c2.DownloadAsync(); </code></pre> <p>I'm sure I'm not using the AggregateCatalog fully here and I need to be able to load any xap's that might be in the directory, not just hardcoding Uri's obviously....</p> <p>Also, in the MainPage.xaml.cs in the host I have the following collection which MEF puts the plugin's into:</p> <pre><code>[ImportMany(AllowRecomposition = true)] public ObservableCollection<IPlugInApp> PlugIns { get; set; } </code></pre> <p>Again, this works, but I'm pretty sure I'm using ImportMany incorrectly....</p> <p>Finally, the MainPage.xaml.cs file implements IPartImportsSatisfiedNotification and I have the following for handling the plugin's once loaded:</p> <pre><code>public void OnImportsSatisfied() { sp.Children.Clear(); foreach (IPlugInApp plugIn in PlugIns) { if (plugIn != null) sp.Children.Add(plugIn.GetUserControl()); } } </code></pre> <p>This works, but it seems filthy that it runs n times (n being the number of xap's to load). I'm having to call sp.Children.Clear() as if I don't, when loading the 2 plugin's, my stack panel is populated as follows:</p> <p>TestPlugIn A TestPlugIn A TestPlugIn B</p> <p>I'm clearly missing something here. Can anyone point out what I should be doing? Thanks!</p>

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