为什么我不能在子类中访问受保护的变量？

Question

我有一个带有受保护变量的抽象类

abstract class Beverage
{
        protected string description;

}

我无法从子类访问它.Intellisense不会显示它可访问.为什么会这样？

class Espresso:Beverage
{
    //this.description ??
}

Answer 1

简答:description是一种称为" 字段 " 的特殊变量.您可能希望阅读MSDN上的字段.

答案很长:您必须在子类的构造函数,方法,属性等中访问受保护的字段.

class Subclass
{
    // These are field declarations. You can't say things like 'this.description = "foobar";' here.
    string foo;

    // Here is a method. You can access the protected field inside this method.
    private void DoSomething()
    {
        string bar = description;
    }
}

在class声明中,您声明类的成员.这些可能是字段,属性,方法等.这些不是要执行的命令性语句.与方法中的代码不同,它们只是告诉编译器类的成员是什么.

在某些类成员(例如构造函数,方法和属性)中,您可以放置​​命令式代码.这是一个例子:

class Foo
{
    // Declaring fields. These just define the members of the class.
    string foo;
    int bar;

    // Declaring methods. The method declarations just define the members of the class, and the code inside them is only executed when the method is called.
    private void DoSomething()
    {
        // When you call DoSomething(), this code is executed.
    }
}