Conditional compilation makes the flow of control harder to follow, and has ill effects on testability. Platform dependencies should be handled using platform specific shadow files, preferably located in a general platform building-block.

exceptions:

• Conditional compilation of header by means of include guards: [ORG#001].
• Conditional application of platform dependent pragmas: see [POR#018].

An example of the last exception is:

  #ifdef VXWORKS
    #pragma SETPLATFORMSPECIFICOPTION
  #endif