[Qgis-developer] prints to std::cout in qgis

[Mateusz Łoskot]

nhugent at hispeed.ch wrote:
> Hi qgissers,
> 
> I will have time to do the implementation of the logger class
> tomorrow. My suggestion is a header as below. QgsLogger would query
> the environment variables QGIS_DEBUG and (if set) QGIS_DEBUG_FILE and
> print out messages or not. 

Yes.

> The question is how the output should be
> controled by QGIS_DEBUG. One possibility would be to have
> QGIS_DEBUG=1 for fatal, QGIS_DEBUG=2 for fatal and critical,
> QGIS_DEBUG=3 for fatal, critical, warning, etc. If QGIS_DEBUG_FILE is
> set, only messages from that file will be printed. Else, messages
> from all files will be printed. What do you think?

I think this is a good idea.

Here is a bit modified version of QgsLogger with simeple use case.
Simply, I'd suggest to use template member what will make it possible to
pass e.g. objects of class types that have ostream operator defined.

#include <QtGlobal>
#include <QString>

#include <sstream>

class QgsLogger
{
public:

static void debug(QString msg, const char* file = 0, const char*
function = 0)
{
   qDebug("File: %s\nFunction: %s\nMessage: %s",
         file, function, msg.toLocal8Bit().data());
}

template <typename T>
static void debug(QString var, T val, const char* file = 0, const char*
function = 0)
{
   std::ostringstream os;
   os << var.toLocal8Bit().data() << " = " << val;

   qDebug("File: %s\nFunction: %s\nMessage: %s",
         file, function, os.str().c_str());
}


// REST OF FUCTIONS

};

Simple use case:



#include "qgslogger.h"

void foo(int x)
{
   QgsLogger::debug("x", x, __FILE__, __FUNCTION__);
}

int main()
{
   QgsLogger::debug("Error occured", __FILE__, __FUNCTION__);

   foo(19);

   return 0;
}

Cheers
-- 
Mateusz Łoskot
http://mateusz.loskot.net