Disable qDebug output locally with a macro

Question

I used qDebug throughout the code. Now I would like to limit its output to translation units, defining a separate macro to enable / disable qDebug output in the translation block:

test.pro:

DEFINES += NO_DEBUG_ONE

testone.cpp:

#ifdef NO_DEBUG_ONE
#define QT_NO_DEBUG_OUTPUT
#endif

testtwo.cpp:

#ifdef NO_DEBUG_TWO
#define QT_NO_DEBUG_OUTPUT
#endif

So by asking macros like this, I expected to get qDebug output only in testtwo.cpp, but I see qDebug messages from both translation units.

What am I missing here and how to solve it?

Answer 1

Move your code to the beginning testone.cppand testtwo.cpp, and you should be good to go.

QT_NO_DEBUG_OUTPUT QT_NO_WARNING_OUTPUT , Qt.

cmake, , qmake.

Answer 2

QMake, , . - -D TEST - .

#ifndef TEST
    qDebug() << "test";
#endif

Answer 3

, QT_NO_DEBUG_OUTPUT , Qt, ( ).

- , :

• , ,

• Define your own debug macro that you can enable or disable:

  // Top of testone.cpp
  #ifdef NO_DEBUG_ONE
    #define DEBUG_MESSAGE(message) 
  #else
    #define DEBUG_MESSAGE(message) qDebug() << message
  #endif
  // In your code
  DEBUG_MESSAGE("This is my debug message");
  

  • The advantage of this is that you do not have #ifndef TESTeverywhere in your code.
• Use logging categories in Qt (recommended)
  • http://blog.qt.io/blog/2014/03/11/qt-weekly-1-categorized-logging/
  • https://www.youtube.com/watch?v=GDtrbIs6JA0

Unfortunately, all of these changes will require code changes.