Why does c# not let me simplify this namespace reference?

Question

I have a project with a namespace and class defined like

namespace My.Company.Project.Models
{
   class Item
   {...}
}

and then in another project I try to use this class:

using My.Company.Project;
...
var obj = new Models.Item

but the compiler says that the "Using directive is unnecessary" and I get an error

CS0246 - The type or namespace name 'Models' could not be found (are you missing a using directive or an assembly reference?)

If my usage instead is

using My.Company;
...
var obj = new Project.Models.Item

it works fine. Why can I use My.Company but not My.Company.Project in my using statement and how can I qualify this so that I don't need such verbose namespace naming of classes?

Answer 1

and then in another project I try to use this class:

And highly likely that this project is in My.Company namespace too. And according to the specification

• The following

  namespace N1.N2
  {
      // ...
  }
  

  is equivalent to

  namespace N1
  {
      namespace N2
      {
          // ...
      }
  }
  

• And (I guess):

  Namespaces are open-ended, and two namespace declarations with the same fully qualified name (§7.8.2) contribute to the same declaration space (§7.3).

So both parts will be in the same My.Company declaration space making using My.Company; actually obsolete (i.e. you should be able to do var obj = new Project.Models.Item(); even without using, at least this is the way I was able to repro the behavior).

If needed you can define an alias for the Models:

using Models = My.Company.Project.Models;

//...
var obj = new Models.Item();