Contents tagged with MEF

  • MEF Preview 9 released

    MEF preview 9 has been released on codeplex

    The only changes are some bug fixes for the .Net version and a couple additions to the SL version.

    • We brought back PackageCatalog but redesigned it under the name DeploymentCatalog and put it in System.ComponentModel.Composition.Initilization.dll
    • We renamed PartCreator to ExportFactory and put it in System.ComponentModel.Composition.Initilization.dll
    • Renamed type PartInitializer to CompositionInitializer
    • Renamed method CompositionHost.InitializeContainer to CompositionHost.Initialize

    This drop contains a MEF.sln which loads in VS2008 and builds MEF against .Net 3.5 and MEFSL.sln which loads in VS2008 and builds MEF againts SL3. The API's are pretty much what we are shipping in .Net 4.0 and SL4 SDK respectively. However if you need a .Net 4 version of MEF we suggest that you install the RC version of .Net 4 and if you need an SL4 version of MEF you install the Silverlight 4 beta SDK.

    As aways if you have issues or questions related to MEF feel free to post them in our dicsussion forums at

    For some more detailed explanations of the changes in this preview have a look at Mike Taulty's post

  • Should MEF support non-shared components?

    Hamilton has posted about the question of whether or not MEF should support non-shared as well as shared components (non-shared==factory and shared==singleton in our current public bits). In an ideal world we would love to support both but currently every solution we've come up with to support non-shared components has issues. We could pick a solution that we feel properly balances the advantages and disadvantages but that would require us to foresee exactly how the world is going to use MEF. While we believe we could pick a reasonable balance there is fear that we would pick the wrong balance for the majority of our future users. Therefore one approach to combat this is to not support non-shared components, at least in V1, and see what usage patterns reveal themselves in the wild and target that balance in V2.

    Do you feel that it would be a mistake for the MEF team to only support shared/singleton components in V1? Keep in mind that there are patterns, as Hamilton pointed out, to still support non-shared/factory if you needed that support in V1.