+class FileLog : public Log
+{
+public:
+ FileLog (boost::filesystem::path file);
+
+private:
+ void do_log (std::string m);
+ /** filename to write to */
+ boost::filesystem::path _file;
+};
+
+class NullLog : public Log
+{
+public:
+
+private:
+ void do_log (std::string) {}
+};
+