D *d = new Adapter();
d->foo();

class C { /* ... */ public: int foo (); int bar (); };

class D /* ... */ { public: int foo (); };

public class C
{
    public void foo()
    {
    }

    public void bar()
    {
    }
}

public class D
{
    public void foo()
    {
    }
}

public interface FooExecutor
{
    void foo();
}

public class CExecutor : FooExecutor
{
    C cMember;

    public CExecutor (C c)
    {
        cMember = c;
    }

    public void foo()
    {
         cMember.foo();
    }
}

public class DExecutor : FooExecutor
{
    D dMember;

    public DExecutor (D d)
    {
        dMember = d;
    }

    public void foo()
    {
         dMember.foo();
    }
}

List<FooExecutor> myList = new List<FooExecutor>();
myList.Add(new CExecutor(new C());
myList.Add(new DExecutor(new D());

foreach (FooExecutor f in myList)
{
    f.foo();
}