Just a few minor overloads and usability tweaks to the logger interface.

dlib/logger/logger_kernel_1.h

@@ -36,10 +36,21 @@ namespace dlib
             name[19] = '\0';
         }
 
+        bool operator< (const log_level& rhs) const { return priority <  rhs.priority; }
+        bool operator<=(const log_level& rhs) const { return priority <= rhs.priority; }
+        bool operator> (const log_level& rhs) const { return priority >  rhs.priority; }
+        bool operator>=(const log_level& rhs) const { return priority >= rhs.priority; }
+
         int priority;
         char name[20];
     };
 
+    inline std::ostream& operator<< (std::ostream& out, const log_level& item)
+    {
+        out << item.name;
+        return out;
+    }
+
     const log_level LALL  (std::numeric_limits<int>::min(),"ALL");
     const log_level LNONE (std::numeric_limits<int>::max(),"NONE");
     const log_level LTRACE(-100,"TRACE");
@@ -79,6 +90,16 @@ namespace dlib
                          const char* message_to_log)
     );
 
+    template <
+        typename T
+        >
+    void set_all_logging_output_hooks (
+        T& object
+    )
+    {
+        set_all_logging_output_hooks(object, &T::log);
+    }
+
 // ----------------------------------------------------------------------------------------
 
     class logger 

dlib/logger/logger_kernel_abstract.h

@@ -35,10 +35,22 @@ namespace dlib
                   is null terminated.
         !*/
 
+        bool operator< (const log_level& rhs) const { return priority <  rhs.priority; }
+        bool operator<=(const log_level& rhs) const { return priority <= rhs.priority; }
+        bool operator> (const log_level& rhs) const { return priority >  rhs.priority; }
+        bool operator>=(const log_level& rhs) const { return priority >= rhs.priority; }
+
         int priority;
         char name[20];
     };
 
+    inline std::ostream& operator<< (std::ostream& out, const log_level& item);
+    /*!
+        ensures
+            - performs out << item.name
+            - returns out
+    !*/
+
 // ----------------------------------------------------------------------------------------
 
     const log_level LALL  (std::numeric_limits<int>::min(),"ALL");
@@ -89,6 +101,17 @@ namespace dlib
             - std::bad_alloc
     !*/
 
+    template <
+        typename T
+        >
+    void set_all_logging_output_hooks (
+        T& object
+    );
+    /*!
+        ensures
+            - calls set_all_logging_output_hooks(object, &T::log);
+    !*/
+
 // ----------------------------------------------------------------------------------------
 
     void set_all_logging_levels (