Adding Preprocessor directive dynamically from commandline build VS2008

I am using VS2008, and developing C/C++ projects. I am using .bat file to build my projects from commandline (VC2k8 command prompt). I need a way to include preprossor directive dynamically at build time.

I am using devenv to build from command line.

>devenv my\project\path\myproject.sln /build release > logs\build.log

Actually I want to set a macro definition based on a command line parameter to the batch file. I can keep two different .vcproj files, but that gives problem in keeping multiple project/sln files. My batch file would something like this...

if (condition)
#define MYPROC_ENABLE_MYMODULE "yes" // To be included in the project.
else
#define MYPROC_ENABLE_MYMODULE "no"

Any help would be really appreciated.

Thanks.

One option would be to set the CL environment variable, using something like:

set CL=/DMYPROC_ENABLE_MYMODULE

The C++ compiler (cl.exe) will add the contents of the CL environment variable to its command line when it runs.

I know you can define macros if you build using msbuild, but I'm not sure you can do the same when using devenv directly.