C#泛型-小心使用静态成员变量

举个例子

using System;

public class List<T>
{   
    public List(T t)
    {
        _value = t;
        _closedCount++;
    }

    public T Value
    {
        get { return _value; }
    }

    public int ClosedCount
    {
        get { return _closedCount; }
    }

    public static int StaticCount
    {
        get { return _closedCount; }
    }

    private T _value;
    private static int _closedCount = 0;
}

public class Test
{
    static void Main()
    {
        List<double> list1 = new List<double>(3.14);
        Console.WriteLine("List1 Value: {0} \t Closed Count: {1}", list1.Value, list1.ClosedCount);

        List<double> list2 = new List<double>(0.618);
        Console.WriteLine("List2 Value: {0} \t Closed Count: {1}", list2.Value, list2.ClosedCount);

        List<string> list3 = new List<string>("divino");
        Console.WriteLine("List3 Value: {0} \t Closed Count: {1}", list3.Value, list3.ClosedCount);

        Console.WriteLine();

        Console.WriteLine("List<double> Count: {0}", List<double>.StaticCount);
        Console.WriteLine("List<string> Count: {0}", List<string>.StaticCount);
    }
}

输出结果：
List1 Value: 3.14         Closed Count: 1
List2 Value: 0.618        Closed Count: 2
List3 Value: divino       Closed Count: 1

List<double> Count: 2
List<string> Count: 1

其中：
list1与list2同为List<double>，它们之间共用静态成员_closedCount
而类型为List<string>的list3不能使用_closedCount
我们从最后两行的输出也可看出结果
即：不同类型参数的封闭构造类型之间是不共享静态成员变量的。