Differentiating class and namespace when class and namespace have the same name

Question

namespace A
{
    class B
    {

    }

    class A
    {
        public void f()
        {
            A.B var = new A.B();
        }
    }
}

Compiled with msvc 2019 and .net core 3.1, this code sample gives the following error:

Error   CS0426  The type name 'B' does not exist in the type 'A'

I understand that it's better not to give the same names for classes and namespace. But is there any way to workaround such collision?

please see this link : https://stackoverflow.com/questions/18731415/namespace-and-class-with-the-same-name — Amin Golmahalleh, Jan 15 '20 at 11:52
Oddly, that linked answer doesn't mention `global::`, which is the technically-correct answer — canton7, Jan 15 '20 at 12:01

StepUp · Answer 1 · 2020-01-15T12:04:17.943

5

There is no need to declare namespace as class B is already declared with the same namespace with class A. So just delete A and Visual Studio will figure out what it is desirable:

namespace A
{
    class B
    {

    }

    class A
    {
        public void f()
        {
            B var = new B();
        }
    }
}

UPDATE:

An alternative solution is:

using _a = A;

namespace A
{
    class B
    {

    }

    class A
    {
        public void f()
        {
            _a.B var = new _a.B();
        }
    }
}

edited Jan 15 '20 at 12:04

answered Jan 15 '20 at 11:51

StepUp

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1

This works in this example, because they happen to live in the same namespace, but personally think @Sefe answer can be more broadly applied. – Michal Ciechan Jan 15 '20 at 11:59
@MichalCiechan yeah, it is great solution. I've upvoted. In addition, I've updated my reply by adding an alternative way. – StepUp Jan 15 '20 at 12:04

score 5 · Accepted Answer · answered Jan 15 '20 at 11:57

You should avoid a scenario where you name your classes and namespaces the same. If you can't or using third party code, you can always refer to the namespace with the global:: keyword:

namespace A
{
    class B
    {

    }

    class A
    {
        public void f()
        {
            global::A.B var = new global::A.B();
        }
    }
}

score 2 · Answer 3 · edited Jan 15 '20 at 11:55

2

I think you are misunderstanding how namespaces work. You don't need to fully qualify B inside class A. You can simply refer to class B because both classes are in the same namespace. Like so:

namespace A
{
    class B
    {

    }

    class A
    {
        public void f()
        {
            B var = new B();
        }
    }
}

edited Jan 15 '20 at 11:55

canton7

37,633
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answered Jan 15 '20 at 11:52

Thomas Cook

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Differentiating class and namespace when class and namespace have the same name

3 Answers3