13.5 - Diagnostic Utilities

Table of Contents

• 13.5.1 Using DtOutputStream for Printing
• 13.5.2 Printing Diagnostic Messages in Windows

You can control the amount of diagnostic information printed by VR-Link by setting the global variable DtNotifyLevel, declared in vlPrint.h.

You can set DtNotifyLevel to any of the following values:

• DtNlFatal Only fatal messages are printed.
• DtNlWarn Warning messages and fatal messages are printed.
• DtNlInfo Some diagnostic information is printed with warnings and fatal messages.
• DtNlVerbose Extra diagnostic information is printed.
• DtNlDebug The maximum information is printed.

The default is DtNlInfo.

You can use the notify level to control messages generated by your own application as well, if you use VR-Link's printing functions rather than printf() or cout() directly. These printing functions are also declared in vlPrint.h, and have the same prototype as printf(). They include:

• DtFatalPerror() and DtWarnPerror(), which print perror information in addition to the information you pass to the function
• DtFatalError()
• DtWarn()
• DtInfo()
• DtVerbose()
• DtDebug().

The fatal functions call DtAbort() after printing their messages.

13.5.1 Using DtOutputStream for Printing

DtOutputStream lets you send debug and informational messages in VR-Link. It uses a buffer and allows you to redirect messages. It works very much like any std::ostream class.

DtInfo, DtWarn, DtVerbose, DtFatal, and DtDebug are all DtOutputStream objects. As such, you can write to them just like any standard C++ output stream, for example:

DtInfo << "something bad just happened, the error is " << error << "\n";

DtOutputStream can attach to one or more DtPrinters. A DtPrinter can print to an output device. VR-Link includes the following DtPrinter subclasses:

• DtFilePrinter. Prints to the specified file.
• DtStdoutPrinter. Prints to stdout
• DtStderrPrinter. Prints to stderr
• DtWindowsConsolePrinter. Prints to a Windows console (Windows only).

By default the DtStdoutPrinter is attached to DtInfo, DtWarn, DtDebug, DtVerbose and DtFatal. You can add any of these subclasses, or your own subclass, to all, or just one of these streams to make DtInfo print to a file, for example:

DtFilePrinter info_log("myInfo.log");
DtInfo.attachPrinter(&info_log);

To print to a console, do the following:

DtInfo.attachPrinter(&DtStandardWindowsConsole)

13.5.2 Printing Diagnostic Messages in Windows

Windows applications that are not console-based do not define STDOUT in the usual way. For example, if you try to use cout or printf to debug a MAK plug-in or to debug VR-Link in an MFC application, it will not work unless you take special care to set up a console and write to it.

To avoid this problem, call the VR-Link function setFileOutput() (defined in vlPrint.h) to enable either writing to a console window or writing to a file. Then, to ensure that diagnostic output gets printed to either the console window or to the file, use VR-Link's printing functions: DtWarn(), DtWarnPerror(), DtInfo(), DtDebug(), and DtVerbose().

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