Visual Studio: How to work with a base code? - visual-studio-2010

Question

In order to support 2 major versions of a CRM SDK I have to have 2 projects that have the same code but different libraries.
The only thing they change in versions are just the imported Libraries, and this not only goes for the default WebProject but all Class Projects that I'm using.
How can I easily have the same code and can test/build for different versions?
For an example:
I have in my Solution:
Class Library: `Authentication.7`
Class Library: `Authentication.6`
Class Library: `Shared.WebControls`
Class Library: `Shared.Utilites`
Web Project: `MyWebApp`
A part of Authentication.6 that really has different code from Authentication.7 library as authentication are very different between these major versions, all other projects just have referenced all needed DLL's from the CRM SDK.
Is there a way to build / test that would load the correct references so I can still use a base code?
What do you guys do in this situations? I'm having a pain to hold into 2 base codes :-/

Answer 1

As long as the base code resides in assemblies with the same names, but with different versions, you could try setting runtime assemblyBindings.
So lets say your assembly is compiled against an earlier version of two base dlls, but you want your same assembly to work with the newer version of the base dlls, add the following to your app|web.config file
<configuration>
<runtime>
<assemblyBinding xmlns="urn:schemas-microsoft-com:asm.v1">
<dependentAssembly>
<assemblyIdentity name="SoCore"
publicKeyToken="bdda2d694ae22a86"
culture="en-us" />
<bindingRedirect oldVersion="7.0.3000.0-7.0.4002.0" newVersion="7.0.4003.0" />
</dependentAssembly>
<dependentAssembly>
<assemblyIdentity name="SoDatabase"
publicKeyToken="bdda2d694ae22a86"
culture="en-us" />
<bindingRedirect oldVersion="7.0.3000.0-7.0.4002.0" newVersion="7.0.4003.0" />
</dependentAssembly>
</assemblyBinding>
</runtime>
</configuration>
Drop in the new assemblies and your assembly - compiled against the older base assemblies, and all should still work - unless the newer base assemblies contains breaking changes in the api you depended on.

Answer 2

One approach would be to have 2 projects for each "identical" library, but use the same set of source files. You can do this by creating a 2nd project (e.g. Shared.WebControls6 and Shared.WebControls7) and using the Add As Link option when adding existing files to the new project - the existing project already has all the files. Note that this has the drawback that any changes to the project files (e.g. adding a new class) needs to happen to both projects.
Another option might be to get fancy within the project file itself. Possibly something like (note: not tested):
<ItemGroup>
<Reference Include="Authentication.7" Condition=" '$(foo)' == '7' " />
<Reference Include="Authentication.6" Condition=" '$(foo)' == '6' " />
</ItemGroup>
<!-- or -->
<ItemGroup>
<Choose>
<When Condition="'$(foo)'=='7'">
<Reference Include="Authentication.7" Condition=" '$(foo)' == '7' " />
</When>
<Otherwise>
<Reference Include="Authentication.6" Condition=" '$(foo)' == '6' " />
</Otherwise>
</Choose>
</ItemGroup>
To build, you'd have to set the value of foo to the version you wish to build against (e.g. msbuild myproj.csproj /p:foo=7).