null_logger.h

00001 #pragma once
00002 
00003 #include "LoggerInterface.h"
00004 
00005 // NullLogger logs nothing but it allows us to inject other logger when necessary.
00006 // With NullLogger we dont have to check if logger is set to actual logger.
00007 // Kudos to Sandi Metz and her seminar on how to avoid if statements
00008 
00009 // Source: http://stackoverflow.com/questions/1008019/c-singleton-design-pattern
00010 namespace LogIt {
00011 
00012   class NullLogger : public Log::LoggerInterface
00013   {
00014     public:
00015       static NullLogger * get_instance()
00016       {
00017         static NullLogger instance;   // Guaranteed to be destroyed.
00018                                       // Instantiated on first use.
00019         return &instance;
00020       }
00021 
00022     private:
00023         NullLogger() {}       // Constructor? (the {} brackets) are needed here.
00024 
00025         // C++ 03
00026         // ========
00027         // Dont forget to declare these two. You want to make sure they
00028         // are unacceptable otherwise you may accidentally get copies of
00029         // your singleton appearing.
00030         NullLogger(NullLogger const&);      // Don't Implement
00031         void operator=(NullLogger const&);  // Don't implement
00032 
00033         // C++ 11
00034         // =======
00035         // We can use the better technique of deleting the methods
00036         // we don't want.
00037     public:
00038         // NullLogger(NullLogger const&) = delete;
00039         // void operator=(NullLogger const&) = delete;
00040 
00041         // Note: Scott Meyers mentions in his Effective Modern
00042         //       C++ book, that deleted functions should generally
00043         //       be public as it results in better error messages
00044         //       due to the compilers behavior to check accessibility
00045         //       before deleted status
00046 
00047       public:
00048         void emergency(const char * message, ...) {};
00049         void alert(const char * message, ...) {};
00050         void critical(const char * message, ...) {};
00051         void error(const char * message, ...) {};
00052         void warning(const char * message, ...) {};
00053         void notice(const char * message, ...) {};
00054         void info(const char * message, ...) {};
00055         void debug(const char * message, ...) {};
00056         void log(Level level, const char * message, ...) {};
00057   };
00058 
00059 };