diff --git a/wrap/callback.h b/wrap/callback.h
index c496591c..3e60c76b 100644
--- a/wrap/callback.h
+++ b/wrap/callback.h
@@ -19,40 +19,62 @@
 * GNU General Public License (http://www.gnu.org/licenses/gpl.txt)          *
 * for more details.                                                         *
 *                                                                           *
-****************************************************************************/
-/****************************************************************************
-  History
-
-$Log: not supported by cvs2svn $
-Revision 1.3  2004/05/12 10:18:55  ganovelli
-new line added at the end of file
-
-Revision 1.2  2004/05/10 14:26:33  ganovelli
-argument name removed to avoid "unreference variable"warning
-
-Revision 1.1  2004/03/03 15:00:51  cignoni
-Initial commit
-
 ****************************************************************************/
 
 #ifndef __VCGLIB_CALLBACK
 #define __VCGLIB_CALLBACK
 
+#include <stdarg.h>  // For va_start, etc.
+#include <memory>    // For std::unique_ptr
+
 namespace vcg {
-// Generic Callback function:
-// Used to make algorithms interumpable
-// Return value: true continue, false break
-// The second callback is to know where we are (useful for progress bar)
-typedef bool CallBack( const char * str );
+/*! \brief This function allow lenghty algorithms to report progress and status.
+ *  
+ * This function is usually called from inside a long processing algorithm 
+ * with a reasonable frequency (e.g. not more that 10 times per sec) 
+ * reporting the what the algorithm is doing and at what point of the processing (as a int percentage) 
+ * we currently are. 
+ * 
+ * Users of the library usually rewrote this function to handle this reporting in the correct way 
+ * (e.g. in a log window and in a progress bar).
+ * 
+ * The algorithms in the library should also check the return value 
+ * to see if the user asked for an interruption, but they can ignore this request
+ * (hint: most of algs in the lib ignore any request).
+ */
+
 typedef bool CallBackPos(const int pos, const char * str );
 
-inline bool DummyCallBack( const char * ) {return true;}
 inline bool DummyCallBackPos(const int ,  const char * ) {return true;}
+inline bool COutCallBackPos(const int ,  const char *str ) {
+  std::cout << str; return true;
+}
+inline bool CErrCallBackPos(const int ,  const char *str ) {
+  std::cerr << str; return true;
+}
+/*! \brief Helper function that formats a string a la printf and returns a simple char*
+ * 
+ * Quite useful for formatting the above callback... 
+ */
 
-/// interruptible function 
-typedef void TaskFunc(int t,void * contest); 
-	
-}	// End namespace
+char* StrFormat(const std::string fmt_str, ...) {
+    int final_n, n = ((int)fmt_str.size()) * 2; /* Reserve two times as much as the length of the fmt_str */
+    std::unique_ptr<char[]> formatted;
+    va_list ap;
+    while(1) {
+        formatted.reset(new char[n]); /* Wrap the plain char array into the unique_ptr */
+        strcpy(&formatted[0], fmt_str.c_str());
+        va_start(ap, fmt_str);
+        final_n = vsnprintf(&formatted[0], n, fmt_str.c_str(), ap);
+        va_end(ap);
+        if (final_n < 0 || final_n >= n)
+            n += abs(final_n - n + 1);
+        else
+            break;
+    }
+    return formatted.get();
+}
 
+}// End namespace
 
 #endif