Here is the link.
From the first page
"However, an important factor in the logging facility's design is the ability to effectively "no-op" the logging statements at compile time."
Note that a stream based compile time on/off method works easily
// in header #ifdef NDEBUG #define MY_DEBUG if( 0 ) cerr #else #define MY_DEBUG if( should_runtime_show() ) \ get_real_stream_reference(); \ else \ get_null_stream_reference(); #endif
// in program MY_DEBUG << "foo" << endl;