Hi! I haven't used boost much yet, but have been looking into lambda expressions. I am working within a huge system, where one of the include files has a macro definition for EXCEPTION. Which is also used as an enum value in boost/lambda/detail/arity_code.hpp (within namespace boost::lambda): enum { NONE = 0x00, // Notice we are using bits as flags here. FIRST = 0x01, SECOND = 0x02, THIRD = 0x04, EXCEPTION = 0x08, RETHROW = 0x10}; Using common names such as this in a general library seems a bit risky to me. Any header before "boost/lambda.hpp" which defines macros for any of these enum values, will cause trouble. I don't have insight enough in boost to suggest the correct solution (or to conclude that I have to fix the problem in my own code and let boost::lambda remain unchanged :-). For me right now the fix was simply replacing the (4) occurences of this EXCEPTION with LAMBDAEXCEPTION in the boost files. Where do I go to put this up as a fix-suggestion? I would like to avoid having to remember this replace every time I upgrade boost... Best regards, Knut Hunstad Vianova Systems AS Norway