问题描述
我想确保永远不会从代码中显式调用方法(在我的情况下实际上是构造函数).它只能在运行时通过反射调用.为此,我想在方法上应用一个属性,如果调用该方法会产生编译器错误,例如:
I would like to ensure that a method (actually a constructor in my case) is never called explicitly from code. It should only be called through reflection at runtime. To do that, I would like to apply an attribute on the method that would generate a compiler error if the method is called, something like :
[NotCallable("This method mustn't be called from code")]
public void MyMethod()
{
}
我知道我可以将方法设为私有,但在这种情况下,我将无法通过部分信任上下文中的反射来调用它...
I know that I could make the method private, but in that case I wouldn't be able to call it through reflection in a partial trust context...
为了完整起见,这里有更多关于我为什么需要这样做的详细信息:
For completeness, here's more details about why I need to do that :
我正在实现一个可重用的 Singleton<T>
类,基于 Jon Skeet 的文章.到目前为止,这是我的代码:
I'm implementing a reusable Singleton<T>
class, based on Jon Skeet's article. Here's my code so far :
public static class Singleton<T>
{
public static T Instance
{
get
{
return LazyInitializer._instance;
}
}
private class LazyInitializer
{
// Explicit static constructor to tell C# compiler
// not to mark type as beforefieldinit
static LazyInitializer()
{
Debug.WriteLine(string.Format("Initializing singleton instance of type '{0}'", typeof(T).FullName));
}
internal static readonly T _instance = (T)Activator.CreateInstance(typeof(T), true);
}
}
(注意我使用 Activator.CreateInstance
创建 T 实例的方式)
(Note the way I create the T instance using Activator.CreateInstance
)
然后我可以将它与这样的类一起使用:
I can then use it with a class like that :
private class Foo
{
protected Foo()
{
}
public string Bar { get; private set; }
}
并调用Singleton<Foo>.Instance
来访问实例.
在部分信任的情况下,它不会工作,因为 Foo
构造函数不是公共的.但是如果我把它公开,没有什么能阻止从代码中显式调用它......我知道我可以在 Foo
构造函数上应用 ObsoleteAttribute
,但它只会生成一个警告,许多人只是忽略警告.
In partial trust, it won't work because the Foo
constructor is not public. But if I make it public, nothing will prevent calling it explicitly from code... I know I could apply the ObsoleteAttribute
on the Foo
constructor, but it will only generate a warning, and many people just ignore warnings.
那么,是否有类似于 ObsoleteAttribute
的属性会生成错误而不是警告?
So, is there an attribute similar to ObsoleteAttribute
that would generate an error instead of a warning ?
任何建议将不胜感激
推荐答案
您可以使用 ObsoleteAttribute 构造函数,它接受一个布尔值,您可以使用它指示调用该方法是一个编译错误:
You can use the ObsoleteAttribute constructor that takes a boolean with which you can indicate that calling the method is a compilation error:
[Obsolete("Don't use this", true)]
但是,如果我是你,我会重新考虑我的设计,因为这样做并不是 API 设计良好的标志.
However, if I were you, I'd reconsider my design, as doing this isn't a sign of a well-designed API.
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