MEF Preview 5

Rohland — Thu, 23 Apr 2009 11:40:37 +0000

Just upgraded to MEF preview 5 and thought I would just post a gotcha that had me puzzled for a few minutes. After upgrading none of my exported parts were being picked up after composing an instance of the composition container class. I was exporting my types as per the example below:

    1 [Export("DataTransformation.Task")]
    2 public class Task : DataTransformationTask
    3 {
    4     // ….
    5 }

With MEF preview 5 you have to explicitly pass the type you are exporting in the Export attribute constructor as per below:

    1 [Export("DataTransformation.Task", typeof(DataTransformationTask))]
    2 public class Task : DataTransformationTask
    3 {
    4     // ….
    5 }

If you would like to find out what else has changed I would recommend taking a read through Glenn Block’s blog review here: http://codebetter.com/blogs/glenn.block/archive/2009/04/11/mef-preview-5-changes-and-enhancements.aspx

Rohland de Charmoy » MEF

MEF Preview 5