派生类 - 扩展属性
我还在学习和战斗派生类。
尝试了一些简单的事情（从我见过的所有示例中）：
public class BaseClass
{
public string Title {get;set;}
}
public class Channel : BaseClass
{
public string Path { get; set; }
}
Channel myChannel = new Channel();
myChannel.Title = "hello";
myChannel.Path = "123";
但是我在 myChannel.Path 行上收到错误，指出 BaseClass 不包含 Path 的定义并且没有扩展名... .
请帮帮我，我做错了什么？
i am still learning and fighting derived classes.
tried something simple ( from the examples i have seen all over ):
public class BaseClass
{
public string Title {get;set;}
}
public class Channel : BaseClass
{
public string Path { get; set; }
}
Channel myChannel = new Channel();
myChannel.Title = "hello";
myChannel.Path = "123";
but i get an error on the myChannel.Path line saying BaseClass does not contain a definition for Path and no extension....
help me please, what am i doing wrong?
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评论（3）
你展示的例子很好。我认为在您的实际代码中您有：
所以答案很简单：确保您的局部变量的类型为
Channel，因为它是表达式类型（通常：类型变量）确定成员解析的起点。作为 C# 3 中的简洁替代方案：
The example you show is fine. I think in your actual code you have:
so the answer is simply: ensure your local variable is typed as
Channel, since it is the the expression type (typically: the type of a variable) that determines the starting point for member resolution.As a terse alternative in C# 3:
您给出的代码编译得很好。我怀疑您实际上有这样的代码：
请注意，这里，
myChannel的编译时类型是BaseClass- 所以编译器不会无法找到Path属性，因为它不存在于BaseClass中。编译器只能根据变量的编译时类型来查找成员。 （将动态类型放在一边...）如果您坚持实际发布的代码，即使用
Channel的编译时类型，那么一切都应该没问题。The code you've given compiles fine. I suspect you've actually got code like this:
Note that here, the compile-time type of
myChannelisBaseClass- so the compiler wouldn't be able to find thePathproperty, as it's not present inBaseClass. The compiler can only find members based on the compile-time type of the variable. (Leaving dynamic typing aside...)If you stick to the code you actually posted, i.e. with a compile-time type of
Channel, then all should be fine.编写的代码运行良好。我怀疑你的情况是
如果是这样，问题是 myChannel 是对 BaseClass 的引用，并且无法看到 Path 属性。
如果您需要访问 Path，您可以使用
hth，
艾伦.
The code as written runs fine. What I suspect you have is
If so, the problem is that myChannel is a reference to a BaseClass and cannot see the Path property.
If you need to access Path you can do so with
hth,
Alan.