Extending the MefModuleManager

Question

I want to extend the MefModuleManager. Now I am searching for a way to do this. First I have created my own ModuleManager:

public class MyModuleManager : MefModuleManager {
    public MyModuleManager(IModuleInitializer moduleInitializer, IModuleCatalog moduleCatalog, ILoggerFacade loggerFacade) : base(moduleInitializer, moduleCatalog, loggerFacade) {
    }

    protected override void HandleModuleTypeLoadingError(ModuleInfo moduleInfo, Exception exception) {
        // ... my Code
    }
}

Now, In my Shell I have (like described in Prism with Mef):

// The shell imports IModuleManager once to load modules on-demand.
// Due to SilverLight/MEF restrictions this must be public.
[Import(AllowRecomposition = false)]
public IModuleManager ModuleManager

I don't know, how to tell Mef, that It should use MyModuleManager instead of MefModuleManager for IModuleManager.

Answer 1

In order to have the MefBootStrapper use different dependencies, you need to declare your custom classes with the [Export] attribute.

Then, if you want Mef to use your custom ModuleManager for a specific type class, you may add a parameter on the attribute for specifying the dependency type which would be resolved as follows:

[Export(typeof(IModuleManager))]
public class MyModuleManager : MefModuleManager
{
    [ImportingConstructor]
    public MyModuleManager(IModuleInitializer moduleInitializer, IModuleCatalog moduleCatalog, ILoggerFacade loggerFacade) : base(moduleInitializer, moduleCatalog, loggerFacade) {
    }

    protected override void HandleModuleTypeLoadingError(ModuleInfo moduleInfo, Exception exception) {
        // ... my Code
    }
}

Notice that I have added an [ImportingConstructor] attribute so the BootStrapper would be able to pass the requested arguments when initializing. That way, Mef would use your custom ModuleManager when a request is made for an IModuleManager instance.

You can refer to the following MSDN Prism Guide chapter for more information:

• 3: Managing Dependencies Between Components

I hope this helped, regards.