error = 1, ///< Log only errors.
warning = 2, ///< Log warnings and errors.
info = 3, ///< Log everything.
+ debug = 4, ///< Log absolutely everything.
};
extern std::ostream& log;
extern std::ostream& null_log;
-extern class log log_error;
-extern class log log_warning;
-extern class log log_info;
+extern class log& log_error;
+extern class log& log_warning;
+extern class log& log_info;
+extern class log& log_debug;
template <class T>