Question

I have a class that is DataContract serialized, and also marked as a shared MEF [Export].

example:

[DataContract(Name="MyClass")]
[Export(typeof(MyClass))]
[PartCreationPolicy(CreationPolicy.Shared)]
public class MyClass
{
    [DataMember]
    public string Field1{get;set;}

    [DataMember]
    public string Field2{get;set;}

    public static MyClass Deserialize(XElement serialized)
    {
        DataContractSerializer ser = new DataContractSerializer(typeof(MyClass));
        MyClass anotherMyClass = (MyClass)ser.ReadObject(serialized.CreateReader());

        return anotherMyClass;
    }
}

I have this marked as a shared export because I only want one instance at a time, but if I reassign an MEF [Import]ed instance of this class (by calling the Deserialize in an assignment) will it still be a singleton? Also, will the other Imported instances reflect this?

Answer 1

The PartCreationPolicy only applies to parts created by MEF. Your Deserialize method doesn’t use MEF, so it will create a new instance. The instance created and managed by MEF will not be updated to match the new instance.