Use existing source code in another project/namespace

Question

I have two library projects within a single solution (in addition to other projects) which necessarily need to share certain classes but must remain separate for automatic-update reasons.

For the classes that are shared, I would ideally like to use the same class.cs file in both libraries so that I don't have to consistently check that changes to the class are propagated through both libraries.

However the namespaces of the two libraries are different, and so the class-containing file in each library requires a different namespace classlib {} declaration.

I am using a git repo, if there is a technique to do this through branch/merge operations.
Presently using VS2013.

How can I achieve this?

---

Example:

library1.dll

namespace library1
{
    public class SharedClass
    {
        /// code must match SharedClass in libary2
    }
}

library2.dll

namespace libary2
{
    public class SharedClass
    {
        /// code must match SharedClass in library1
    }
}

Answer 1

Declare the SharedClass in a common namespace, instead of two different namespaces. You could link the file into the projects instead of including it physically.

From msdn:

You link to a file from your project in Visual Studio. In Solution Explorer, right-click your project, and then select Add Existing item Or, you can type Shift+Alt+A. In the Add Existing Item dialog box, select the file you want to add, and in the Add drop-down list, click Add As Link.

namespace Khargoosh.MathLib.Common   { public class SharedClass { ... }  }
namespace Khargoosh.MathLib.Library1 { ... }
namespace Khargoosh.MathLib.Library2 { ... }

or

namespace Khargoosh.MathLib          { public class SharedClass { ... }  }
namespace Khargoosh.MathLib.Library1 { ... }
namespace Khargoosh.MathLib.Library2 { ... }

---

A completely other way of handling that would be to use the T4 template with some logic to create the file dynamically. Content of the *.tt template files (not *.cs files!):

namespace library1
{
<#@ include file="MyCommonClass.cs"#>
}

And in the other library

namespace library2
{
<#@ include file="MyCommonClass.cs"#>
}

The class file itself would not declare a namespace.

Answer 2

Based on the info you've provided, if your shared classes are truly "common" you should create a 3rd library that both of your main libs can reference. for example:

MainLib1 (reference commonLib)

MainLib2 (reference commonLib)

commonLib (includes class.cs and other common code)