为什么尽管有“使用”声明，但仍需要包括我的部分名称空间？

Question

I have one project in my solution geared towards providing some core functionality. It's namespace is MyCompanyName.ProductName.FunctionSet . At this time, this project includes two classes; customer.cs and core.cs . The core class is static and contains a static method EntryPoint().

I have a console app in the solution. Its namespace is MyCompanyName.ProductName.TaskMan . I created a reference to the core project above and added a using directive for the namespace.

One of the lines in Main() is Core.EntryPoint(); . Note, it does not include any part of the namespace. The code was running fine.

Now, in order to resolve an error (Cannot resolve symbol 'EntryPoint') I needed to change the line to FunctionSet.Core.EntryPoint(); . I needed to add the last part of the namespace.

Why did I need to add that portion of the namespace? Any ideas why it suddenly stopped working? Is there anything I can do to omit the namespace portion? It's not a big deal if I'm stuck with this but I do want to know the how and why.

Answer 1

EDIT: I've preserved the bulky bit below, but I'm now not sure it's relevant.

I suspect that one of these is true:

• Your namespaces aren't quite what you think they are (in particular for Core)
• You don't have the using directive you think you do

If you could post a short but complete program (just the two classes should be enough, and just the namespace, using directives, class declaration and methods - no need for any business logic) it should be easy enough to sort out.

---

Namespaces aren't resolved relative to using directives, although they are resolved relative to the current namespace. For example:

namespace Outer.Inner
{
    class Foo
    {
        public static void Bar() {}
    }
}

namespace Outer.OtherInner
{
    class Test1        
    {
        static void Method()
        {
            // Resolved to Outer.Inner.Foo.Bar()
            Inner.Foo.Bar();
        }
    }
}

namespace OtherOuter
{
    using Outer;

    class Test2
    {
        static void Main()
        {
            // This is invalid
            Inner.Foo.Bar();
        }
    }
}

For the full gory details, look at section 3.8 of the C# specification.

Answer 2

Have you tried adding the function in a using statement at the beginning of the file?

using FunctionSet.Core.EntryPoint
EntryPoint();