I have a NuGet package for a library that is currently implemented only for .NET 4. But I have ported library code to support various platforms (WinRT, SL5, WP8) so ideally I would like to package it as a portable class library (PCL) to simplify the maintenance. But the library is using LINQ to XML (XELements etc.) that requires targeting .NET 4.0.3 and installting .NET 4.0.3 on a client machine.
So I have a dilemma regarding how to target plain .NET 4. If it was not about NuGet packages and I had a control of the user base I could simply state as a prerequisite installing .NET 4.0.3 runtime. However, I don't want to limit the user base in any way, so it looks like I will have to have two versions of the library: portable that targets .NET 4.5, SL5 and WP8 and non-portable targeting just .NET4. What's silly is that both libraries will have exactly the same code since LINQ to XML is of course supported in .NET 4, it's just PCLs that don't have such support when targeting .NET 4.
My first question is whether this seems to be a right strategy? The alternative would be to take away all XElement-dependent code from PCL and have it in non-portable parts, but this does not seem right because the code will be exactly the same for all libraries.
The second question is whether it makes sense to target .NET 4.0.3 from a PCL at all: if I have separate version targeting .NET 4 will users that have .NET 4.0.3 runtime installed gain anything from getting a PCL rather than plain .NET 4 version? I know .NET 4.0.3 has other improvements but those don't affect my library.