c# - 使用私有(private)静态方法的优势

Question

当创建一个具有内部私有(private)方法的类时，通常是为了减少代码重复，不需要使用任何实例字段，将方法声明为静态是否有性能或内存优势？

例子:

foreach (XmlElement element in xmlDoc.DocumentElement.SelectNodes("sample"))
{
    string first = GetInnerXml(element, ".//first");
    string second = GetInnerXml(element, ".//second");
    string third = GetInnerXml(element, ".//third");
}

...

private static string GetInnerXml(XmlElement element, string nodeName)
{
    return GetInnerXml(element, nodeName, null);
}

private static string GetInnerXml(XmlElement element, string nodeName, string defaultValue)
{
    XmlNode node = element.SelectSingleNode(nodeName);
    return node == null ? defaultValue : node.InnerXml;
}

将 GetInnerXml() 方法声明为静态方法有什么好处吗？没有意见请回复，我有意见。

Answer 1

来自FxCop rule page对此:

After you mark the methods as static, the compiler will emit non-virtual call sites to these members. Emitting non-virtual call sites will prevent a check at runtime for each call that ensures that the current object pointer is non-null. This can result in a measurable performance gain for performance-sensitive code. In some cases, the failure to access the current object instance represents a correctness issue.