C# 中的单例“无法访问”什么时候不在同一个命名空间中?
我尝试通过以下方式实现单例类(我使用VS2008 SP1):
namespace firstNamespace
{
class SingletonClass
{
private SingletonClass() {}
public static readonly SingletonClass Instance = new SingletonClass();
}
}
当我想从不同名称空间中的类访问它时(似乎这就是问题所在,在同一个名称空间中它可以工作),例如
namespace secondNamespace
{
...
firstNamespace.SingletonClass inst = firstNamespace.SingletonClass.Instance;
...
}
:出现编译器错误:
error CS0122: 'firstNamespace.SingletonClass' is inaccessible due to its protection level
有人知道如何解决这个问题吗?
非常感谢!
I tried to implement a singleton class in the following way (I use VS2008 SP1) :
namespace firstNamespace
{
class SingletonClass
{
private SingletonClass() {}
public static readonly SingletonClass Instance = new SingletonClass();
}
}
When I want to access it from a class in a different namespace (it seems that this is the problem, in the same namespace it works) like :
namespace secondNamespace
{
...
firstNamespace.SingletonClass inst = firstNamespace.SingletonClass.Instance;
...
}
I get a compiler error:
error CS0122: 'firstNamespace.SingletonClass' is inaccessible due to its protection level
Does somebody have an idea how to solve this?
Many thanks in advance!
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评论(6)
您的 SingletonClass class 不是公共的,因此在
命名空间程序集之外不可见。更正:评论是正确的,正如msdn:
You SingletonClass class is not public, so isn't visible outside the
namespaceassembly.Correction: the comments are right, as says msdn:
SingletonClass 具有内部可见性,因此如果两个命名空间位于不同的程序集中,则整个类将无法访问。
更改
为
The SingletonClass has internal visibility, so if the two namespaces are in different assemblies, the entire class in inaccessible.
Change
to
更改
为
将其标记为公开,因此可访问
甚至更好:
,因为成员是静态的:
这里有更多内容
change
to
to mark it public, thus accessible
or even better:
since the members are static:
more here
您的类
SingletonClass
在其他命名空间中是可见的。但它在其他程序集/项目中不可见。你的课程是私人的。这意味着当前项目 (=Assembly = .dll) 中的所有代码都可以看到此类。然而,该类对于其他项目中的代码是隐藏的。
命名空间和程序集之间的相关性很弱。一个命名空间可以存在于多个程序集中,例如 mscorlib.dll 和 System.dll 都包含 System 命名空间。
但通常情况下,当您在 Visual Studio 中创建新项目时,您会获得一个新的命名空间。
您还可以向一个程序集添加多个命名空间。当您创建新文件夹时,这会在 Visual Studio 中自动发生。
You class
SingletonClass
is visible in other namespaces. But it is not visible in other Assemblies/Projects.Your class is private. This means all code in your current project (=Assembly = .dll) can see this class. The class is however hidden for code in other projects.
There is a weak correlation between the namespace and the assembly. One namespace can exist in multiple assemblies, for example mscorlib.dll and System.dll both contain the System namespace.
But normally, when you create a new project in Visual Studio, you get a new namespace.
You can also add multiple namespaces to the one Assembly. This happens automatically in Visual Studio when you create a new folder.
您的类定义中缺少关键字
public
。You're missing the keyword
public
from your class definition.听起来更像是单例位于不同的程序集中。类的默认修饰符是内部的,因此只能在程序集中访问。
Sounds more like the singleton is in a different assembly. The default modifier for a class is internal and thereby only accessible in the assembly.