Diff: loggers/null_logger.h

Revision:

4:9c5143891c8a

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/loggers/null_logger.h	Wed Dec 14 18:06:34 2016 +0100
@@ -0,0 +1,59 @@
+#pragma once
+
+#include "LoggerInterface.h"
+
+// NullLogger logs nothing but it allows us to inject other logger when necessary.
+// With NullLogger we dont have to check if logger is set to actual logger.
+// Kudos to Sandi Metz and her seminar on how to avoid if statements
+
+// Source: http://stackoverflow.com/questions/1008019/c-singleton-design-pattern
+namespace LogIt {
+
+  class NullLogger : public Log::LoggerInterface
+  {
+    public:
+      static NullLogger * get_instance()
+      {
+        static NullLogger instance;   // Guaranteed to be destroyed.
+                                      // Instantiated on first use.
+        return &instance;
+      }
+
+    private:
+        NullLogger() {}       // Constructor? (the {} brackets) are needed here.
+
+        // C++ 03
+        // ========
+        // Dont forget to declare these two. You want to make sure they
+        // are unacceptable otherwise you may accidentally get copies of
+        // your singleton appearing.
+        NullLogger(NullLogger const&);      // Don't Implement
+        void operator=(NullLogger const&);  // Don't implement
+
+        // C++ 11
+        // =======
+        // We can use the better technique of deleting the methods
+        // we don't want.
+    public:
+        // NullLogger(NullLogger const&) = delete;
+        // void operator=(NullLogger const&) = delete;
+
+        // Note: Scott Meyers mentions in his Effective Modern
+        //       C++ book, that deleted functions should generally
+        //       be public as it results in better error messages
+        //       due to the compilers behavior to check accessibility
+        //       before deleted status
+
+      public:
+        void emergency(const char * message, ...) {};
+        void alert(const char * message, ...) {};
+        void critical(const char * message, ...) {};
+        void error(const char * message, ...) {};
+        void warning(const char * message, ...) {};
+        void notice(const char * message, ...) {};
+        void info(const char * message, ...) {};
+        void debug(const char * message, ...) {};
+        void log(Level level, const char * message, ...) {};
+  };
+
+};