Activator.CreateInstance with private sealed class

Question

I\'m trying to new up a LocalCommand instance which is a private class of System.Data.SqlClient.SqlCommandSet. I seem to be able to grab the type information just fine:

Answer 1

Trick is to make sure to use the right CreateInstance overload:

// WRONG
... Activator.CreateInstance(
       type,
       BindingFlags.Instance
       | BindingFlags.NonPublic
    );

This calls the params overload, which will default to Instance | Public | CreateInstance, and your binding flags will be passed as arguments to the constructor, giving the vague MissingMethodException.

Also, use Instance | Public | NonPublic if you aren't sure of the visibility of the constructor:

// right
... Activator.CreateInstance(
       type,
       BindingFlags.Instance
       | BindingFlags.Public
       | BindingFlags.NonPublic,
       null,
       new object[] { }, // or your actual constructor arguments
       null
    );