MEF - [ImportMany]使用ExportFactory&LT; T&GT;在WPF - .NET 4.0

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问题描述

我有一些进口的部分，我需要创建的多个实例。通过围绕搜索，我决定我需要使用ExportFactory类。不幸的是，ExportFactory类不可用WPF中默认，但幸运的是格伦座具有

I have some part imports that I need to create multiple instances of. By searching around I decided I needed to use the ExportFactory class. Unfortunately, the ExportFactory class is not available in WPF by default, but luckily Glenn Block has ported the code.

本来，我是导入时指定类型：

Originally, I was specifying the type when importing:

[ImportMany(typeof(IMyModule))]
public IEnumerable<Lazy<IMyModule, IMyModuleMetadata>> Modules { get; set; }

我还创建了一个出口属性：

I also created an export attribute:

[MetadataAttribute]
[AttributeUsage(AttributeTargets.Class, AllowMultiple=false)]
public class ExportMyModuleMetadata : ExportAttribute, IMyModuleMetadata
{
    public ExportMyModuleMetadata(string category, string name)
        : base(typeof(IMyModuleData))
    {
        Category = category;
        Name = name;
    }
    public string Category { get; set; }
    public string Name { get; set; }
}

我的出口是这样的：

My export looks like this:

[ExportMyModuleMetadata("Standard","Post Processor")]
[PartCreationPolicy(CreationPolicy.NonShared)]
public class Module1 : IMyModuleData

以上的进口工作的罚款。但是，一旦我改变了懒< T，T> 到 ExportFactory< T，T> 我开始撰写期间错误

The above import worked fine. But once I changed Lazy<T,T> to ExportFactory<T,T> I started getting an error during composition.

[ImportMany(typeof(IMyModule))]
public IEnumerable<ExportFactory<IMyModule, IMyModuleMetadata>> Modules { get; set; }

我得到的错误信息是：

The error message I got was:

The export 'Module1 (ContractName="IMyModule")' is not assignable to type
'System.ComponentModel.Composition.ExportFactory`

我看到的地方（我找不到链接现在）的指定键入在 ImportMany 属性的问题。我想没有，所以我删除从类型我可以做的 ImportMany 。

I saw somewhere (that I can't find the link for right now) that specifying the Type in the ImportMany attribute is the problem. I figured I could do without it so I removed the type from the ImportMany.

[ImportMany()]
public IEnumerable<Lazy<IMyModule, IMyModuleMetadata>> Modules { get; set; }

使用时，该进口仍然工作懒< T，T> ，但一旦我把它改为 ExportFactory< T，T> ，我不再进口任何东西。我没有得到一个错误了，但没有得到进口的。

This import still worked when using Lazy<T,T>, but once I changed it to ExportFactory<T,T>, I no longer import anything. I didn't get an error anymore but nothing gets imported.

有谁知道如何正确使用 ImportMany 与 ExportFactory< T，T> 为WPF

Does anyone know how to properly use ImportMany with ExportFactory<T,T> for WPF?

更新：

随着韦斯的关于添加 ExportFactoryProvider（），我得到了 ExportFactory<尖; T，T> .NET 4的工作！，以下是更新的组成码

With Wes's tip about adding an ExportFactoryProvider(), I got the ExportFactory<T,T> working in .NET 4! Below is the updated composition code.

var ep = new ExportFactoryProvider();

//Looks for modules in main assembly and scans folder of DLLs for modules.
var moduleCatalog = new AggregateCatalog(
    new AssemblyCatalog(runningApp),
    new DirectoryCatalog(".", "*.dll"));
var container = new CompositionContainer(moduleCatalog, ep);
ep.SourceProvider = container;
var Modules = new Modules();
container.ComposeParts(Modules);

我也发现了这个讨论在的，讨论多一点这个问题。

I also found a discussion on this at MEF Codeplex site that talks a little more about this.

ExportFactory

MEF - [ImportMany]使用ExportFactory&LT; T&GT;在WPF - .NET 4.0

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