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Use of TypeCatalog

I thought this would be easy, but after scanning many pages Google hasn't come to my aid.

I have the following in a test method.

var tCatalog = new TypeCatalog(typeof (ISystemIndex));
var aCatalog = new AssemblyCatalog(typeof (ISystemIndex).Assembly);

tCatalog.Parts comes up empty, while aCatalog.Parts.Count is 3 (one of them comes from a class decorated with [Export(typeof(ISystemIndex))], the other two from classes inheriting from a base w/ Export defined)

What am I doing wrong? Do I need to initialize the TypeCatalog in some way?

The problem I'm trying to solve is to create a catalog with a subset of the exportable classes in my assembly.

Thanks in advance.

Solution

  • You're trying to create a TypeCatalog for the interface definition, which is not exported, as there is no [Export] attribute decorating the ISystemIndex interface.

    If you had a class such as

    [Export(typeof(ISystemIndex))]
public class MySystemIndex : ISystemIndex
{
}

    and you would create a type catalog

    var tCatalog = new TypeCatalog(typeof(MySystemIndex));

    then you would have seen it in tCatalog.Parts.

    EDIT

    If you want to have a catalog filtered by a certain criteria (e.g. in your case, exports only), check out MEF's documentation about Filtering Catalogs