How to pass parameter to candle in command line and let it overwrite the value in the target .wxs

Question

I'm working on a MSBUILD script to dynamically inject a number of parameters to a wix project for several builds, and I understand I can use -d switch in candle to supply additional params.

However I'm getting several warnings similar to "The variable 'xxx' with value 'yyy' was previously declared with value 'zzz'", This is understandable as in the .wxs I already have these values defined for a default build, the build will then carry on using the values from .wxs after the warnings.

So the question is..is it possbile to force candle to overwrite these parameters which are already in .wxs..

Thanks in advance.

Answer 1

Preprocessor variables can only be defined once so you need something like:

<?ifndef Variable ?>
  <?define Variable="default" ?>
<?endif?>

to protect against redefinition. This is the same as with the C/C++ preprocessor that the WiX toolset was modeled after.