LSL Trick: Do something when the file is run through a preprocessor, and something different otherwise

include-if-preprocessor-active.lsl

string dummy="/*\
";

// insert here code that will only be compiled when the preprocessor is active
#include "debug.h"

/*/""; // separator line

// insert here code that will only be compiled when the preprocessor is inactive
debug(string s){llOwnerSay(s);}

// */

/* Rest of file here */
default{timer(){}}

// It takes advantage of a bug in the grammar, where a double quote is ignored
// if there is a backslash at the end of a line before the next double quote.

// As a side effect, it defines a string variable 'dummy',
// which will be "/*" if there was a preprocessor, and ""
// otherwise.

// Tested with LSL PyOptimizer, mcpp, GNU cpp, Firestorm preprocessor, lslint, and plain SL.