From Valeriy Onuchin:

- I introduced debugPrint function which
  prints debugging message to stderr and to the system debugger under Windows.

Printing to the system debugger is usfull for debugging pure GUI (without console)
appications under MS Windows.


git-svn-id: http://root.cern.ch/svn/root/trunk@8053 27541ba8-7e3a-0410-8455-c3a389f83636

base/src/TError.cxx

-// @(#)root/base:$Name:  $:$Id: TError.cxx,v 1.5 2002/11/18 23:02:19 rdm Exp $
+// @(#)root/base:$Name:  $:$Id: TError.cxx,v 1.6 2004/01/14 07:41:03 rdm Exp $
 // Author: Fons Rademakers   29/07/95
 
 /*************************************************************************
@@ -21,6 +21,10 @@
 //                                                                      //
 //////////////////////////////////////////////////////////////////////////
 
+#ifdef WIN32
+#include <windows.h>
+#endif
+
 #include <stdio.h>
 #include "snprintf.h"
 
@@ -36,6 +40,42 @@ const char *kCheckMsg  = "%s not true at line %d of `%s'";
 
 static ErrorHandlerFunc_t gErrorHandler = DefaultErrorHandler;
 
+
+//______________________________________________________________________________
+static void debugPrint(const char *fmt, ...) 
+{
+   // print debugging message to stderr and to the system debugger under Windows
+
+   static Int_t buf_size = 2048;
+   static char *buf = 0;
+
+   char *bp;
+
+   va_list arg_ptr; 
+   va_start(arg_ptr, fmt);
+
+again:
+   if (!buf)
+      buf = new char[buf_size];
+
+   int n = vsnprintf(buf, buf_size, fmt, arg_ptr);
+
+   if (n == -1 || n >= buf_size) {
+      buf_size *= 2;
+      delete [] buf;
+      buf = 0;
+      goto again;
+   }
+   va_end(arg_ptr);
+
+   fprintf(stderr, "%s", buf);
+
+#ifdef WIN32
+   ::OutputDebugString(buf);
+#endif
+}
+
+
 //______________________________________________________________________________
 ErrorHandlerFunc_t SetErrorHandler(ErrorHandlerFunc_t newhandler)
 {
@@ -79,15 +119,15 @@ void DefaultErrorHandler(int level, Bool_t abort, const char *location, const ch
       type = "Fatal";
 
    if (level >= kBreak && level < kSysError)
-      fprintf(stderr, "%s %s\n", type, msg);
+      debugPrint("%s %s\n", type, msg);
    else if (!location || strlen(location) == 0)
-      fprintf(stderr, "%s: %s\n", type, msg);
-   else
-      fprintf(stderr, "%s in <%s>: %s\n", type, location, msg);
+      debugPrint("%s: %s\n", type, msg);
+   else 
+      debugPrint("%s in <%s>: %s\n", type, location, msg);
 
    fflush(stderr);
    if (abort) {
-      fprintf(stderr, "aborting\n");
+      debugPrint("aborting\n");
       fflush(stderr);
       if (gSystem) {
          gSystem->StackTrace();