有谁知道为什么？

有没有更简单的方法来获得接口的共享实现？

当我遭受多重继承/混合撤销时,这让我感到烦恼.

玩具示例：

public interface ITest
{
    List<string> TestList { get; }
}

public static class TestExtensions
{
    private const string Old = "Old";
    private const string New = "New";

    public static void ManipulateTestList(this ITest test)
    {
        for (int i = 0; i < test.TestList.Count; i++)
        {
            test.TestList[i] = test.TestList[i].Replace(Old,New);
        }
    }
}

public class Tester : ITest
{
    private List<string> testList = new List<string>();
    public List<string> TestList
    {
        get { return testList; }
    }

    public Tester()
    {
        testList.Add("OldOne");
        testList.Add("OldTwo");

        // Doesn't work
        // ManipulateTestList();

        // Works
        this.ManipulateTestList();
    } 
}