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I'm organizing a library project and I have a central manager class named Scenegraph and a whole bunch of other classes that live in the Scenegraph namespace.

What I'd really like is for the scenegraph to be MyLib.Scenegraph and the other classes to be MyLib.Scenegraph.*, but it seems the only way to do that would be to make all the other classes inner classes of Scenegraph in the Scenegraph.cs file and that's just too unwieldy.

Instead, I've organized it as Mylib.Scenegraph.Scenegraph and MyLib.Scenegraph.*, which sort of works but I find Visual Studio gets confused under some conditions as to whether I am referring to the class or the namespace.

Is there a good way to organize this package so it's convenient for users without glomming all my code together in an unmaintainable mess?

afuzzyllama
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user430788
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  • [❌ DO NOT use the same name for a namespace and a type in that namespace](https://learn.microsoft.com/en-us/dotnet/standard/design-guidelines/names-of-namespaces) – H H Dec 07 '22 at 21:19

9 Answers9

140

I don't recommend you to name a class like its namespace, see this article.

The Framework Design Guidelines say in section 3.4 “do not use the same name for a namespace and a type in that namespace”. That is:

namespace MyContainers.List 
{ 
    public class List { … } 
}

Why is this badness? Oh, let me count the ways.

You can get yourself into situations where you think you are referring to one thing but in fact are referring to something else. Suppose you end up in this unfortunate situation: you are writing Blah.DLL and importing Foo.DLL and Bar.DLL, which, unfortunately, both have a type called Foo:

// Foo.DLL: 
namespace Foo { public class Foo { } }

// Bar.DLL: 
namespace Bar { public class Foo { } }

// Blah.DLL: 
namespace Blah  
{   
using Foo;   
using Bar;   
class C { Foo foo; } 
}

The compiler gives an error. “Foo” is ambiguous between Foo.Foo and Bar.Foo. Bummer. I guess I’ll fix that by fully qualifying the name:

   class C { Foo.Foo foo; }

This now gives the ambiguity error “Foo in Foo.Foo is ambiguous between Foo.Foo and Bar.Foo”. We still don’t know what the first Foo refers to, and until we can figure that out, we don’t even bother to try to figure out what the second one refers to.

Pang
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pinckerman
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    The response says "what not to do". While some of stack users looks for "what to do". Would anyone recommend Ant_222 answer? – Fantastory Nov 20 '14 at 14:18
  • The compiler finds ambiguity if you name a class and its namespace with the same name, so it's correct to answer "what not to do". Moreover *Ant_222* answer suggests to change the namespace name too, so I don't think he wrote something more than me. – pinckerman Nov 20 '14 at 16:39
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    If you're really stuck, you can still create a type alias outside your namespace. External aliases are only needed when you have two completely identical full identifiers (namespace + class name). – Geoffrey Nov 25 '15 at 15:07
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    All of the above is by-the-bye and opinion. The *fact* is that you shouldn't do it because **the C# compiler will misunderstand it**, despite being told quite clearly what's going on. E.g., `using Foo.Bar;` then later `Bar b` is quite clearly referring to `Bar`, a class (or enum) inside the namespace `Foo.Bar`. The real reason not to do that is purely that the C# compiler fails to correctly understand it, which is awfully surprising and unfortunate. Anything else is woolly style advice. – T.J. Crowder Feb 06 '16 at 15:06
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    I don't get it. Why Foo.Foo is ambiguous? You directly say to compiler that you want to use class Foo from the namespace Foo in this specific case. No? – GuardianX Jun 29 '16 at 22:23
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    The explanation does not make sense. That's the whole purpose of having a namespace in a programming language. – user3113045 Sep 19 '19 at 19:14
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    Indeed I think this explanation does not answer the question because such ambiguity can happen anywhere for any other reason. That's why the language has `using Foo1 = Foo` or `global::Foo.Foo`. – fjch1997 Oct 10 '19 at 15:09
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    It's not an answer if there is a way to do what is asked, you just don't like it. – Kendall Helmstetter Gelner Sep 02 '20 at 21:40
  • why not make your namespaces lowercase ? would that not remove all risk of collision ? – Fred Haslam Feb 19 '21 at 03:45
25

Giving the same name to the namespace and the class can confuse the compiler as others have said.

How to name it then?

If the namespace has multiple classes then find a name that defines all those classes.

If the namespace has just one class (and hence the temptation to give it the same name) name the namespace ClassNameNS. This is how Microsoft names their namespaces at least.

GoTo
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    Do you have an example of such a namespace from Microsoft? – sunefred Dec 07 '18 at 20:11
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    @sunefred I searched it, but I could not find it. But I definitely remember to have seen it in the documentation. I guess there are not many cases when you want to have a single class in a namespace. – GoTo Dec 18 '18 at 21:26
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    I downvoter because this did not solve the problem and I have never seen a namespace with "NS" at the end.... This definitely not how it is done – Jonathan Alfaro Jun 02 '22 at 13:57
21

Even though I agree with other answers in that you should not name your class the same as your namespace there are times in which you cannot comply with such requirements.

In my case for example I was not the person making such a decision therefore I needed to find a way to make it work.

So for those who cannot change namespace name nor class name here is a way in which you can make your code work.

// Foo.DLL: 
namespace Foo { public class Foo { } }

// Bar.DLL: 
namespace Bar { public class Foo { } }

// Blah.DLL: 
namespace Blah
{
    using FooNSAlias = Foo;//alias
    using BarNSAlias = Bar;//alias
    class C { FooNSAlias.Foo foo; }//use alias to fully qualify class name
}

Basically I created namespace "aliases" and that allowed me to fully qualify the class and the Visual Studio "confusion" went away.

NOTE: You should avoid this naming conflict if it is under your control to do so. You should only use the mentioned technique when you are not in control of the classes and namespaces in question.

Jonathan Alfaro
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12

I would suggest that you follow the advice I got on microsoft.public.dotnet.languages.csharp to use MyLib.ScenegraphUtil.Scenegraph and MyLib.ScenegraphUtil.*.

Anton Shepelev
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11

As others have said, it's a good practice to avoid naming a class the same as its namespace.

Here are some additional naming suggestions from an answer by svick to a related question "Same class and namespace name" on the Software Engineering Stack Exchange:

You're right that you shouldn't name the namespace the same as a type it contains. I think there are several approaches you can use:

  • Pluralize: Model.DataSources.DataSource

This works especially well if the primary purpose of the namespace is to contain types that inherit from the same base type or implement the same interface.

  • Shorten: Model.QueryStorage

If a namespace contains only a small number of types, maybe you don't need that namespace at all.

  • Make enterprisey: Model.ProjectSystem.Project

This can work especially for features that are important part of your product, so they deserve their own name.

sonnyb
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9

It happens when it's the main class of the namespace. So it's one motivation to put the namespace in a library, then the issue goes away if you add 'Lib' to the namespace name...

namespace SocketLib
{
    class Socket
    {
Paul Sumpner
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  • Clean solution. I was using dots like `Lib.Socket` and ran into problems when the classname was the same. Using less dots now. – robsn Nov 27 '20 at 07:57
7

CA1724: Type Names Should Not Match Namespaces ...

Basically, if you follow Code Analysis for proper coding this rule says to not do what you are trying to do. Code Analysis is very useful in helping you find potential issues.

myermian
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6

Old post, but here I go with another idea that may help someone:

"...but it seems the only way to do that would be to make all the other classes inner classes of Scenegraph in the Scenegraph.cs file and that's just too unwieldy."

This is really the better implementation for a bunch of scenarios. But, I do agree that having all that code on the same .cs file is annoying (to say the least).

You could solve it by making the base class a "partial class" and then, go on creating the inner classes on their own files (just remember that they'll have to declare the base class complement and then go on with the specific inner class for that file).

Something like...

Scenegraph.cs:

namespace MyLib
{
    public partial class Scenegraph
    {
        //Scenegraph specific implementations
    }
}

DependentClass.cs:

namespace MyLib
{
    public partial class Scenegraph
    {
        public class DependentClass
        {
            //DependentClass specific implementations
        }
    }
}

I do think that this is the closer that you can get to having the clean implementation of inner classes while not having to clutter everything inside one huge and messy file.

Marcelo Myara
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4

Just Adding my 2 cents:

I had the following class:

namespace Foo {
    public struct Bar {
    }
    public class Foo {
        //no method or member named "Bar"
    }
}

The client was written like this:

using Foo;

public class Blah {
    public void GetFoo( out Foo.Bar[] barArray ) {
    }
}

Forgiving the error GetFoo not returning the output instead of using the out parameter, the compiler could not resolve the data type Foo.Bar[] . It was returning the error: could not find type or namespace Foo.Bar .

It appears that when it tries to compile it resolved Foo as the class and did not find an embedded class Bar in the class Foo. It also could not find a namespace called Foo.Bar . It failed to look for a class Bar in the namespace Foo. The dots in a name space are NOT syntactic. The whole string is a token, not the words delimited by the dots.

This behaviour was exhibited by VS 2015 running .Net 4.6

Steve
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