log开启与屏蔽的一种调式方式

#ifndef _LOGGING_H
#define _LOGGING_H

#define deg printf

#ifdef ENABLE_TRACING
#define ENTER() do { fprintf(stderr, "%s: ENTER\n", __FUNCTION__); } while(0)
#define LEAVE() do { fprintf(stderr, "%s: LEAVE\n", __FUNCTION__); } while(0)
#else
#define ENTER() do { } while(0)
#define LEAVE() do { } while(0)
#endif