trace.h Example File

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  #ifndef TRACE_H
  #define TRACE_H

  #include <QtCore/QDebug>

  #define ENABLE_TRACE
  //#define VERBOSE_TRACE

  namespace Trace {

  class NullDebug
  {
  public:
      template <typename T>
      NullDebug& operator<<(const T&) { return *this; }
  };

  inline NullDebug nullDebug() { return NullDebug(); }

  template <typename T>
  struct PtrWrapper
  {
      PtrWrapper(const T *ptr) : m_ptr(ptr) { }
      const T *const m_ptr;
  };

  } // namespace Trace

  template <typename T>
  inline QDebug& operator<<(QDebug &debug, const Trace::PtrWrapper<T> &wrapper)
  {
      QDebugStateSaver saver(debug);
      debug.nospace() << '[' << static_cast<const void *>(wrapper.m_ptr) << ']';
      return debug;
  }

  template<typename T>
  inline const void *qtVoidPtr(const T *ptr)
  { return static_cast<const void *>(ptr); }

  #define qtThisPtr() qtVoidPtr(this)

  #ifdef ENABLE_TRACE
          inline QDebug qtTrace() { return qDebug() << "[qmlvideo]"; }
  #    ifdef VERBOSE_TRACE
          inline QDebug qtVerboseTrace() { return qtTrace(); }
  #    else
          inline Trace::NullDebug qtVerboseTrace() { return Trace::nullDebug(); }
  #    endif
  #else
      inline Trace::NullDebug qtTrace() { return Trace::nullDebug(); }
      inline Trace::NullDebug qtVerboseTrace() { return Trace::nullDebug(); }
  #endif

  #endif // TRACE_H