WPF：如何在Prism + MEF中重新加载AggregateCatalog？

Question

How to properly reload Prism's AggregateCatalog ? When a file changes, I need Prism to reload its catalog, but it keeps giving me this error:

An unhandled exception of type 'System.ComponentModel.Composition.ChangeRejectedException' occurred in System.ComponentModel.Composition.dll

Here is the Bootstrapper snippet. It fails when I clear the AggregateCatalog.

class Bootstrapper : MefBootstrapper
{
    private readonly FileSystemWatcher _fileWatcher;

    public Bootstrapper()
    {
        _fileWatcher = new FileSystemWatcher(Path.Combine(System.AppDomain.CurrentDomain.BaseDirectory, "Modules"));
        _fileWatcher.Created += fileWatcher_Changed;
        _fileWatcher.Changed += fileWatcher_Changed;
        _fileWatcher.Deleted += fileWatcher_Changed;
        _fileWatcher.Renamed += fileWatcher_Changed;
        _fileWatcher.EnableRaisingEvents = true;
    }

    private void fileWatcher_Changed(object sender, FileSystemEventArgs e)
    {
        this.AggregateCatalog.Catalogs.Clear(); //It fails here!
        ConfigureAggregateCatalog();
        ConfigureContainer();
    }

Answer 1

It is not possible to do that. When the application starts the module catalog is built during for initialisation and thereafter it is not used anymore and even destroyed. So dynamically, without restarting the application, adding modules is not possible with prism.