在枚举上使用XOR运算符重载GetHashCode和相等运算符

我有下面的课程,它是静态分析包的一部分。

• 这个 MetricKey 对象用作字典键。
• Decision , MetricUnit 和; Portfolio 都是枚举。

我必须重写相等运算符(==)才能使字典键匹配工作。我在 http://msdn.microsoft.com/en-us/library/ms173147.aspx . 指南说我应该重载gethashcode方法,我已经做过了,但是我不理解将枚举强制转换为xor(^)操作的整数的含义。由于枚举整数值重叠,我所做的是有效的还是会得到冲突的哈希代码?:

public class MetricKey
{
    public MetricKey(Decision decision, MetricUnit metricUnit, Portfolio portfolio)
    {
        Decision = decision;
        Unit = metricUnit;
        Portfolio = portfolio;
    }

    public Decision Decision { get; private set; }
    public MetricUnit Unit { get; private set; }
    public Portfolio Portfolio { get; private set; }

    public static bool operator == (MetricKey a, MetricKey b)
    {
        if (ReferenceEquals(a, b))
            return true;
        if (((object) a == null) || ((object) b == null))
            return false;
        return a.Decision == b.Decision && a.Unit == b.Unit && a.Portfolio == b.Portfolio;
    }

    public static bool operator != (MetricKey a, MetricKey b)
    {
        return !(a == b);
    }

    public override bool Equals(System.Object obj)
    {
        if (obj == null)
            return false;
        var metricKey = obj as MetricKey;
        if ((System.Object) metricKey == null)
            return false;
        return Decision == metricKey.Decision && Unit == metricKey.Unit && Portfolio == metricKey.Portfolio;
    }

    public bool Equals(MetricKey metricKey)
    {
        if ((object) metricKey == null)
            return false;
        return Decision == metricKey.Decision && Unit == metricKey.Unit && Portfolio == metricKey.Portfolio;
    }

    public override int GetHashCode()
    {
        return (int)Decision ^ (int)Unit ^ (int)Portfolio;
    }
}