title: multi file C program, how best to implement optional logging?
body: <p>I have a multi file C program. I'd like the user to be able to specify different debugging levels at run time.</p>
  
  <p>What is the best way to implement this?</p>
  
  <p>I was thinking of having a debug(level, "message") type function exported and used everywhere. Any better/other ideas?</p>