title: how to #define macro only to specific files?
body: <p>I have a special macro defined in macro.h, but I want it to be valid only in part of my source files (h/cpp),
  how can I do that?</p>
  
  <p>I am afraid that some "bad" user included the macro.h before the source files that must not be familiar with the macro.</p>
  
  <p>how can I prevent it?</p>