Conditional Reference

Question

I have an application that I was writing that communicates with a third-party application via a Component Object Model library. I must reference this COM library within the Visual Studio project itself in order for the application I am writing to work. There is also a .NET wrapper library that I must reference in the Visual Studio project in order to communicate with the COM library.

Is there a way to to create a conditional initialization of a class, in order to use a method within a .NET class within the .NET wrapper library, that will work in a later version of the third-party COM library itself.

The problem I ran into was that I was trying to reference a feature of the COM library that only existed in a later version. The version of the wrapper itself was identical because it was backwards compatible. When I attempted to access this new feature the program I was writing would silently close when I started it when the previous version of the third-party application was installed.

Is there a way I could have avoided this behavior without changing how the way the application itself was built?

Glaab

Answer 1

Not sure whether I understand term "reference a class".

You can do a conditional referencing of an entire Assembly (DLL)

<Reference 
        Include="LegacyServices.dll" 
        Condition="$(AppVersion == '2.0')" />

or conditionally include a source file into a project

<Compile 
       Include="LegacyServices.cs" 
       Condition="$(AppVersion == '2.0')" />

Both using MSBuild Condition in csproj file.

Otis

The thing you posted doesn't work. It says condition evaluated to '' instead of bool. Even msdn page you are refering to says it has to be $(AppVersion) == '2.0'. Also such references confuse visual studio (references appears even when condition is false), meanwhile that answer works fine with visual studio. – Santana

Could you try Condition=" '$(AppVersion)' == '2.0'" – Otis

That would work too, but I don't know how visual studio will treat that and I don't care because <Choose><When> worked fine and it's much better for multiple conditional references I have. – Santana