How to add macro's definition in cmake?

Question

I am using Mongodb client and Boost in my C++ application. Because the Mongodb client is still using Boost old filesystem and my C++ application is using filesystem version 3 fr

Answer 1

Take a look at add_definitions, which will add your definitions to your compiler command line, e.g. -D with gcc, or /D with MSVC. Try something like:

add_definitions( -DBOOST_FILESYSTEM_VERSION=2 )

In your case, I would definitely go with the add_definition method, but an alternative may to take a look at configure_file. Then you can create a header-file template, which will be filled with cmake-values and include this in your source files. This can be useful if you have many, many configurable parameters which are determined by CMake.