C# 嵌套类属性

Question

在 C# 中，为什么嵌套类必须实例化其父类，才能在代码中引用其父类非静态属性？

public class OuterClass
{
    public int OuterClassProperty
    {
        get
        {
            return 1;
        }
    }

    public class InnerClass
    {
        public int InnerClassProperty
        {
            get
            {
                /* syntax error: cannot access a non-static
                 * member of outer type via nested type.
                 */
                return OuterClassProperty;
            }
        }
    }
}

看来我必须这样做:

public class OuterClass
{
    public int OuterClassProperty
    {
        get
        {
            return 1;
        }
    }

    public class InnerClass
    {
        public int InnerClassProperty
        {
            get
            {
                OuterClass ImplementedOuterClass = new OuterClass();
                return ImplementedOuterClass.OuterClassProperty;
            }
        }
    }
}

我认为第一个代码示例应该没问题，因为如果实例化 InnerClass，则父类将首先实现 - 以及父类属性。

感谢您的帮助，我正在尝试学习 C# 的细节...而且我对 Java 不熟悉，与 Java 相比没有多大帮助...

Answer 1

您所观察到的行为已在 C# 规范中明确说明。下面是 C# 5.0 的片段:

10.3.8.4 this access
A nested type and its containing type do not have a special relationship with regard to this-access (§7.6.7). Specifically, this within a nested type cannot be used to refer to instance members of the containing type. In cases where a nested type needs access to the instance members of its containing type, access can be provided by providing the this for the instance of the containing type as a constructor argument for the nested type.

C# 中嵌套类的行为与其他语言不同，例如 Java inner classes in c#和C+因为C#是不同语言设计团队创建的不同语言。选择特定行为的确切历史原因可以在 C# 设计团队成员的博客、.Net 设计指南书籍或 MSDN 文章中找到。