Q:

Can I make a constant from a compile-time env variable in csharp?

We use Hudson to build our projects, and Hudson conveniently defines environment variables like "%BUILD_NUMBER%" at compile time.  
I'd like to use that variable in code, so we can do things like log what build this is at run time.  However I CAN NOT do System.Environment.GetEnvironmentVariable because that is accessing the run-time environment, what I want is something like:
#define BUILD_NUM = %BUILD_NUMBER%

or
const string BUILD_NUM = %BUILD_NUMBER%

Except I don't know the syntax.  Can someone please point me in the right direction?  Thanks!

A:

Okay here's what I wound up doing.  It's not very elegant, but it works.  I created a pre-build step that looks like this:
echo namespace Some.Namespace > "$(ProjectDir)\CiInfo.cs"
echo { >> "$(ProjectDir)\CiInfo.cs"
echo     ///^<summary^>Info about the continuous integration server build that produced this binary.^</summary^> >> "$(ProjectDir)\CiInfo.cs"
echo     public static class CiInfo >> "$(ProjectDir)\CiInfo.cs"
echo     { >> "$(ProjectDir)\CiInfo.cs"
echo         ///^<summary^>The current build number, such as "153"^</summary^> >> "$(ProjectDir)\CiInfo.cs"
echo         public const string BuildNumber = ("%BUILD_NUMBER%" == "" ? @"Unknown" : "%BUILD_NUMBER%"); >> "$(ProjectDir)\CiInfo.cs"
echo         ///^<summary^>String of the build number and build date/time, and other useful info.^</summary^> >> "$(ProjectDir)\CiInfo.cs"
echo         public const string BuildTag = ("%BUILD_TAG%" == "" ? @"nohudson" : "%BUILD_TAG%") + " built: %DATE%-%TIME%"; >> "$(ProjectDir)\CiInfo.cs"
echo     } >> "$(ProjectDir)\CiInfo.cs"
echo } >> "$(ProjectDir)\CiInfo.cs"

Then I added "CiInfo.cs" to the project, but ignored it from version control.  That way I never have to edit it or commit it, and the project always has a constant available that is the latest build number and time.

A:

One way to do it is to add a build-step before compilation which does a regex replace in the appropriate source file(s) for %BUILD_NUMBER%.

A:

One possibility is to use T4 to generate your configuration class with all the constants instantiated. T4 is well-integrated into MSVS, no need for your own custom build step.

