ATLTRACE2

Article
12/01/2015

Reports warnings to an output device, such as the debugger window, according to the indicated flags and levels.

Syntax

      ATLTRACE2( 
      exp 
      );
ATLTRACE2(
   DWORD category,
   UINT level,
   LPCSTR lpszFormat,
   ...
);

Parameters

exp
[in] The string to send to the Visual C++ output window or any application that traps these messages.
category
[in] Type of event or method on which to report. See the Remarks for a list of categories.
level
[in] The level of tracing to report. See the Remarks for details.
lpszFormat
[in] The printf-style format string to use to create a string to send to the dump device.

Remarks

The short form of ATLTRACE2 writes a string to the debugger's output window. The second form of ATLTRACE2 also writes output to the debugger's output window, but is subject to the settings of the ATL/MFC Trace Tool (see ATLTraceTool Sample). For example, if you set level to 4 and the ATL/MFC Trace Tool to level 0, you will not see the message. level can be 0, 1, 2, 3, or 4. The default, 0, reports only the most serious problems.

The category parameter lists the trace flags to set. These flags correspond to the types of methods for which you want to report. The tables below list the valid trace flags you can use for the category parameter.

ATL Trace Flags

ATL Category	Description
atlTraceGeneral	Reports on all ATL applications. The default.
atlTraceCOM	Reports on COM methods.
atlTraceQI	Reports on QueryInterface calls.
atlTraceRegistrar	Reports on the registration of objects.
atlTraceRefcount	Reports on changing reference count.
atlTraceWindowing	Reports on windows methods; for example, reports an invalid message map ID.
atlTraceControls	Reports on controls; for example, reports when a control or its window is destroyed.
atlTraceHosting	Reports hosting messages; for example, reports when a client in a container is activated.
atlTraceDBClient	Reports on OLE DB Consumer Template; for example, when a call to GetData fails, the output can contain the HRESULT.
atlTraceDBProvider	Reports on OLE DB Provider Template; for example, reports if the creation of a column failed.
atlTraceSnapin	Reports for MMC SnapIn application.
atlTraceNotImpl	Reports that the indicated function is not implemented.
atlTraceAllocation	Reports messages printed by the memory debugging tools in atldbgmem.h.

MFC Trace Flags

MFC Category	Description
traceAppMsg	General purpose, MFC messages. Always recommended.
traceDumpContext	Messages from CDumpContext.
traceWinMsg	Messages from MFC's message handling code.
traceMemory	Messages from MFC's memory management code.
traceCmdRouting	Messages from MFC's Windows command routing code.
traceHtml	Messages from MFC's DHTML dialog support.
traceSocket	Messages from MFC's socket support.
traceOle	Messages from MFC's OLE support.
traceDatabase	Messages from MFC's database support.
traceInternet	Messages from MFC's Internet support.

To declare a custom trace category, declare a global instance of the CTraceCategory class as follows:

CTraceCategory MY_CATEGORY(_T("MyCategoryName"), 1);

The category name, MY_CATEGORY in this example, is the name you specify to the category parameter. The first parameter is the category name that will appear in the ATL/MFC Trace Tool. The second parameter is the default trace level. This parameter is optional, and the default trace level is 0.

To use a user-defined category:

ATLTRACE2(MY_CATEGORY, 2, _T("a message in a custom category"));

To specify that you want to filter the trace messages, insert definitions for these macros into Stdafx.h before the #include <atlbase.h> statement.

Alternatively, you can set the filter in the preprocessor directives in the Property Pages dialog box. Click the Preprocessor tab and then insert the global into the Preprocessor Definitions edit box.

Atlbase.h contains default definitions of the ATLTRACE2 macros and these definitions will be used if you don't define these symbols before atlbase.h is processed.

In release builds, ATLTRACE2 compiles to (void) 0.

ATLTRACE2 limits the contents of the string to be sent to the dump device to no more than 1023 characters, after formatting.

ATLTRACE and ATLTRACE2 have the same behavior, ATLTRACE is included for backward compatibility.

Example

int i = 1;
ATLTRACE2(atlTraceGeneral, 4, "Integer = %d\n", i);
// Output: 'Integer = 1'

Requirements

Header: atltrace.h

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