C#

ObjectHandle o;
IPlugin plugin;
Type t = Type.GetType("SomeAssembly.dll");
o = Activator.CreateInstance(t);
plugin = (IPlugin)o.Unwrap();
plugin.Render();

ObjectHandle o;
IPlugin plugin;
string dll = PluginManager.strPath + @"\" + pluginList.SelectedItem;

Type t = Type.GetType(dll);
o = Activator.CreateInstance(dll, t.ToString());
plugin = (IPlugin)o.Unwrap();

MessageBox.Show(plugin.Author);

string assname = typeof(PluginManager).Assembly.FullName;
string typename = typeof(PluginManager).FullName;

pm = plugdom.CreateInstanceAndUnwrap(assname, typename, 
   true, BindingFlags.Default, null, this.objs, null, null, null) as PluginManager;

A a = new B();

interface IHandleWithInvalidate
{
  IntPtr Handle{get;}
  void Invalidate();
}

class myComponent
{
    private IHandleWithInvalidate passedObject;
    
    public myComponent(Form f)
    {
        this.passedObject = f;
    }

    public myComponent(Control c)
    {
        this.passedObject = c;
    }

    private void DoSomething()
    {
        this.passedObject.Invalidate();
        IntPtr h = this.passedObject.Handle;
    }
}

class myComponent
{
    private Form passedForm;
    private Control passedControl;
    
    public myComponent(Form f)
    {
        this.passedForm = f;
    }

    public myComponent(Control c)
    {
        this.passedControl = c;
    }

    private void DoSomething()
    {
        if(this.passedForm != null)
        {
            this.passedForm.Invalidate();
            IntPtr h = this.passedForm.Handle;
        }
        else
        {
            this.passedControl.Invalidate();
            IntPtr h = this.passedControl.Handle;
        }
    }
}

public SpecialC#Construct
{
   has a .Close method
}

public class myComponent
{
   private SpecialC#Construct passedObject;
  
   public myComponent(DataView v)
   {
      this.passedObject = v; // compiler could verify that the DataView has a .Close method
   }

   public myComponent(BinaryWriter b)
   {
      this.passedObject = b; // compiler could verify the BinaryWriter has a .Close method
   }

   public void DoSomething()
   {
      this.passedObject.Close();
   }
}

public class myComponent
{
   private DataView passedDataView;
   private BinaryWriter passedWriter; // ACK! I have to store 2 variables even though I'm using just 1
  
   public myComponent(DataView v)
   {
      this.passedDataView = v;
   }

   public myComponent(BinaryWriter b)
   {
      this.passedWriter = b;
   }

   public void DoSomething() // this is where it gets ugly
   {
      if(passedDataView != null)
      {
         passedDataView.Close();
      }
      else
      {
         passedBinaryWriter.Close();
      }
   }
}