5

Is there a way to reference a namespace globally across the whole solution?

So instead of having these lines in every code file:

using System;
using MyNamespace;

having to declare them only once, and every code file would use them.

Btw I am using Visual Studio.

Joan Venge
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  • In C# 10 and above, you can use `global using`: https://learn.microsoft.com/en-us/dotnet/csharp/language-reference/keywords/using-directive#global-modifier – Tohid Aug 01 '23 at 11:00

7 Answers7

6

No, C# doesn't have this concept. Each source file is independent in this respect. (And if the using directives are in a namespace declaration, those are independent from other using directives in peer namespace declarations, too. That's a pretty rare case though in my experience.)

You don't need ReSharper to change what gets included in a new class though. You can use the Visual Studio templates.

EDIT: Just to clarify the point about using directives within namespaces, suppose we had (all in one file):

using Foo;

namespace X
{
    using Bar;
    // Foo and Bar are searched for code in here, but not Baz
}

namespace Y
{
    using Baz;
    // Foo and Baz are searched for code in here, but not Bar
}

Usually I only have one namespace declaration in a file, and put all the using directives before it.

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Jon Skeet
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  • You're amazing. Every time I see (or post) an answer that looks complete and final to me, you come up with something better :) – Philippe Leybaert Jun 04 '09 at 18:37
  • Thanks Jon. In your 3rd sentence do you mean, if you have namespace declaration inside another namespace (CustomNS), and if you use the CustomNS, those namespaces wouldn't be included for a file that uses that namespace? – Joan Venge Jun 04 '09 at 18:48
  • Thanks Jon. What about adding "using X;" inside namespace Y? I actually tried but it didn't give me access to what's inside Bar (which is included in X). – Joan Venge Jun 04 '09 at 19:18
  • No, it wouldn't. A using directive only affects the look-up for source code within that namespace declaration (or the whole file if it's at the top). It doesn't embed that lookup into the generated code or anything like that. – Jon Skeet Jun 05 '09 at 05:29
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    This answer is a bit outdated now, as others have pointed out there is now a notion of a project-wide `global using ns` that at least partially achieve what the OP is looking for. – Peter Lillevold Jun 21 '23 at 13:10
5

No, this is not possible.

If you're using ReSharper, you can set an option to include specific using directives in every new file you create though.

Philippe Leybaert
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2

In C# 10.0 you can use Global Usings.

global using System;
global using MyNamespace;
Misha Zaslavsky
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2

No, you can not reference a namespace globally across the whole solution in .NET or .NET CORE.

But you can use project wise namespace globally in solution. this feature will be available from c#10/.NET 6. currently it's in preview but it will be released in NOV 2021

=========Project level .NET 6 global using namespace=========

Create a class file at root of the project e.g GlobalNamespace.cs

global using System;
global using System.Linq;
global using System.Text.RegularExpressions;
global using System.Threading.Tasks;

Then you don't need to declare using namespace in other .cs files of the project which are already declared globally.

Rohit Jadhav
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2

From this SO question and follow-up blog post. You can edit the Visual Studio default templates.

To do this, look at the file in this zip : [Program Files][Visual Studio]\Common7\IDE\ItemTemplates\CSharp\Code\1033\Class.zip

and modify the Class.cs file as needed. Additionally, Visual Studio may have cached this file here : [Program Files][Visual Studio]\Common7\IDE\ItemTemplatesCache\CSharp\Code\1033\Class.zip

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Timothy Carter
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0

As others have mentioned Visual Studio Templates are the way to go.

Note that simply adding a using statement to your template will not ensure that the compiler can resolve your types. So, if you are adding a using statement for MyNamespace in every class you may need to add an assembly reference to your project as well. See the C# FAQ for more information.

Randy Levy
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-3

One trick I miss as a newb to CSharp is to look at the "refences" (in VS), to right click and "Add New Reference". This is especially handy when combining mulitple projects where I have made some generic class for reuse elsewhere.

adamskijl
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