How do I know if user-defined namespaces are part of the unnamed namespace?

Question

0.00/5 (No votes)

See more:

Assume we have the following code in C# source code file file1.cs. According to C# specs because class Class1 is not explicitly defined within a user-defined namespace (named namespace) it is instead defined within the "unnamed namespace":

public class Class1
{
    //body
}

In the bottom example I define a user-defined namespace SampleNamespace. Say defined in C# source code file file2.cs. In a different source code file from which class Class1 is found in. My question is: Is namespace SampleNamespace also defined within the "unnamed namespace"? Just as how class Class1 is defined in the unnamed namespace?

namespace SampleNamespace
{
    public class Class2
    {
        //body
    }
}

What I have tried:

Microsoft, C# langauge, Visual Studio, Langauge specs

Posted 26-Aug-21 9:49am

MShanoda

Updated 26-Aug-21 14:32pm

v2

Add a Solution

2 solutions

Add a Solution

Add your solution here

Treat my content as plain text, not as HTML

Preview 0

…

Existing Members

Sign in to your account

...or Join us

Download, Vote, Comment, Publish.

Your Email
Password
Forgot your password?

Your Email
This email is in use. Do you need your password?
Optional Password

I have read and agree to the Terms of Service and Privacy Policy
Please subscribe me to the CodeProject newsletters

When answering a question please:

Read the question carefully.
Understand that English isn't everyone's first language so be lenient of bad spelling and grammar.
If a question is poorly phrased then either ask for clarification, ignore it, or edit the question and fix the problem. Insults are not welcome.
Don't tell someone to read the manual. Chances are they have and don't get it. Provide an answer or move on to the next question.

Let's work to help developers, not make them feel stupid.

This content, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

BillWoodruff · Answer 1 · 2021-08-26T14:32:00

Solution 2

It seems you have discovered the "Global" NameSpace: I would call it "root," or, "default," but, "unnamed" makes no sense

There are aspects of this NameSpace that you may find unexpected. Few programmers work directly with the Global NameSpace: using it to hold application-wide variables and data is considered poor practice, a violation of SOLID principles.

For sample usages, see: [^]

I can't describe the complexity of the Global NameSpace better than this :) c# - What is global::? - Stack Overflow[^]

Posted 26-Aug-21 14:32pm

BillWoodruff

Comments

MShanoda 26-Aug-21 20:58pm

Hi there, I concur that "unnamed namespace" is not the best term to use. However I use that term as it was the C# language spec uses as well.

According to https://docs.microsoft.com/en-us/dotnet/csharp/language-reference/keywords/namespace : "The compiler adds a default namespace. This unnamed namespace, sometimes referred to as the global namespace, is present in every file."

Concerning the question in my post though, the other user who answered my question claimed that (root) user-defined namespace are not part of the unnamed namespace.

In contradiction to his claim, I found an MS documentation that claims otherwise: "Namespaces and types that have no enclosing namespace are members of the global namespace. This corresponds directly to the names declared in the global declaration space. Namespaces and types declared within a namespace are members of that namespace. This corresponds directly to the names declared in the declaration space of the namespace."

Source: https://docs.microsoft.com/en-us/dotnet/csharp/language-reference/language-specification/basic-concepts#:~:text=Hiding%20through%20inheritance).-,Namespace%20members,-Namespaces%20and%20types

What do you make of the above statement. It clearly states that (root) user-defined namespaces are defined in the unnamed namespace. Right?

BillWoodruff 27-Aug-21 3:25am

If you have issues with what Dave said, take that up with him.

Are you here to learn to be a better programmer, and, to appreciate the people who volunteer to assist you, or, are you here to engage in a semantic debate which is pointless ?

Dave Kreskowiak · Answer 2 · 2021-08-26T11:39:00

Solution 1

No, it doesn't. Your's is just another "root" namespace, just like System or Microsoft.

You can create other child namespaces just by including your root namespace before the child.

C#

namespace SampleNamespace
{
    public Class1
    {
    }
}

C#

namespace SampleNamespace.ChildNamespace
{
    public SomeClass
    {
    }
}

Posted 26-Aug-21 11:39am

Dave Kreskowiak

Comments

MShanoda 26-Aug-21 18:24pm

Your solution adds on to the point I was making.

To paraphrase, isn't SampleNamespace also child of the (root) unnamed namespace? similar to how ChildNamespace is a child to the SampleNamespace.

Dave Kreskowiak 26-Aug-21 18:26pm

There is no unnamed namespace above SampleNamespace. It's just another "root" namespace:

System
Microsoft
SampleNamespace
unnamed

MShanoda 26-Aug-21 18:33pm

Then are you saying that the unnamed namespace is only a parent to "types" not defined in a user-defined namespace? And so does not apply any (root) user-defined namespace that I define?

Dave Kreskowiak 26-Aug-21 18:52pm

Yes, but "does not apply" has no definition so I don't know what you mean by that.

MShanoda 26-Aug-21 19:02pm

I meant if you were saying the same (the unnamed namespace is a parent to ***) does not apply to user-defined (root) namespaces in a source code file. Which based on conversation. I pressume yes.

To add on to that, I haven't read any online source that states what you are claiming. Is there any way to test the claim you are making in code?

That the unnamed namespace is not a parent to any (root) user-defined namespace I define.

Dave Kreskowiak 26-Aug-21 19:13pm

Again, "does not apply to user-defined (root) namespaces" doesn't mean anything.

Namespaces are for organization of types, not limiting access to them.

If you have a class without a namespace, you can still use that class anywhere else in your code, no matter what namespace that code sits under.

MShanoda 26-Aug-21 19:52pm

According to an MS doc: "Namespaces and types that have no enclosing namespace are members of the global namespace. This corresponds directly to the names declared in the global declaration space. Namespaces and types declared within a namespace are members of that namespace. This corresponds directly to the names declared in the declaration space of the namespace."

Source: https://docs.microsoft.com/en-us/dotnet/csharp/language-reference/language-specification/basic-concepts#:~:text=Hiding%20through%20inheritance).-,Namespace%20members,-Namespaces%20and%20types