is there any way of specifying the type of a generic class during runtime instead of at compile time?

my problem is that i have file several different versions of a file with each version having different properties and methods and it is not unitl compile time that i can findout what version of the file it is. Below is examples of the classes that i have

public class version1_0
{
   //example member
   public int total;
}

public class version2_2
{
   //example member
   public string extendedDesc;
}

public Gen<T>
{
   public T file;

   //other methods are here
}

public enum Versions
{
   v1, //represents the version1_0 class
   v2 //represents the version2_2 class
}

i want to add the generic class "Gen" to the class below using the _file variable and then set the type of the generic class Gen by the version that was passed into the constructor so i can specify the type of the Gen variable at compile time only at run time.
public class myFile
{
   private Gen??? _file;

   public myFile(Versions)
   {
      //set type of _file here by using Versions enum.
   }
}

is there any other way that i could go about solving this problem?

many thanks in advance.

Glenn

Please don't cross post. See:

http://p2p.wrox.com/topic.asp?TOPIC_ID=22912

instead

Jim Minatel
Senior Acquisitions Editor
Wiley Technology Publishing
WROX Press
Jim's Book of the week: Beginning XML 3rd Edition

Declare an Interface and implement the interface in each of the version of classes. In the final class you declare a type for the interface, so at run time you can assign instance of any of the derived class.


It is not how much we do,
but how much love we put in the doing.

-Mother Theresa