CMake command line for C++ #define

Question

I need to compile different versions of a certain project by adding compiler switches. Usually I would do this by using add_definitions or something like

set_p         


        

Answer 1

I managed to do it this way now:

I was able to convince everybody to add the following lines to the common CMakeLists.txt:

IF (NOT DEFINED _MYDEFINE)
    SET(_MYDEFINE )
ENDIF()
ADD_DEFINITIONS(-D_MYDEFINE=${_MYDEFINE})

(No it is not really called "MYDEFINE", and is just a placeholder, I just replaced all that for this example)

This does not change the current behaviour of compiling with no additional compiler flags and is thus a valid change.

And it allows you to do

cmake -D_MYDEFINE= 

where this cmake definition will be mapped to a C++ precompiler definition when cmake creates the project file.