C#

public class Foo<T> : IEnumerable<T> {
    private List<T> someList;	
    IEnumerator<T> IEnumerable<T>.GetEnumerator();
    System.Collections.IEnumerator System.Collections.IEnumerable.GetEnumerator();
}

public class GenericClass<T>
{
    T a;
    public List<T> xxx()
        { .... }
}

new GenericClass<Int32[]>();

new GenericClass<List<Int32>>();

public class GenericClass<T>
{
    private List<T> a = null;

    public GenericClass(IEnumerable<T> items)
    {
        if (items != null)
            a = new List<T>(items);
    }

    public List<T> Xxx()
    {
        return a;
    }
}