Question

I want to to use boost auto_cpu_timer to display the time my complete code needs to run. Additionally i want to see the progress of my loops using progress_display.

It seems there is a namespace confilict as Boost has two timer classes, where progress_display is from the old, now deprecated library.

http://www.boost.org/doc/libs/1_51_0/libs/timer/doc/index.html

Still, is there a way to achieve this? The following example shows, what i’m trying to do. Using either AUTO or PROG works fine, but both together result in error messages.

Main: compiled with g++ -lboost_timer main.cc -o time

#define AUTO
#define PROG

#ifdef  PROG
#include <boost/progress.hpp>
#endif     //----  PROG  -----

#ifdef  AUTO
#include <boost/timer/timer.hpp>
#endif     //----  AUTO  -----

#include <cmath>

int main()
{
#ifdef  AUTO
    boost::timer::auto_cpu_timer t;
#endif     //----  AUTO  -----

    long loops = 100000000;

#ifdef  PROG
    boost::progress_display pd( loops );
#endif     //----  PROG  -----

    //long loop to burn some time
    for (long i = 0; i < loops; ++i)
    {
        std::sqrt(123.456L);
#ifdef  PROG
        ++pd;
#endif     //----  PROG  -----
    }

    return 0;
}

Error log:

/usr/include/boost/timer/timer.hpp:38:1: error: ‘namespace boost::timer { }’ redeclared as different kind of symbol
/usr/include/boost/timer.hpp:45:1: error: previous declaration of ‘class boost::timer’
/usr/include/boost/timer/timer.hpp: In member function ‘std::string boost::timer::cpu_timer::format(short int, const std::string&) const’:
/usr/include/boost/timer/timer.hpp:74:34: error: ‘format’ is not a member of ‘boost::timer’
/usr/include/boost/timer/timer.hpp: In member function ‘std::string boost::timer::cpu_timer::format(short int) const’:
/usr/include/boost/timer/timer.hpp:76:34: error: ‘format’ is not a member of ‘boost::timer’
main.cc: In function ‘int main()’:
main.cc:17:2: error: ‘auto_cpu_timer’ is not a member of ‘boost::timer’
main.cc:17:31: error: expected ‘;’ before ‘t’

Answer 1

When you include boost/progress.hpp, the C++ compiler sees a definition for boost::timer as class timer defined in boost/timer.hpp that is included in boost/progress.hpp.

When you include boost/time/timer.hpp, the C++ compiler sees another definition for boost::timer as a namespace and this is the cause of the error.

If you really want to use it, the solution is renaming one of those boost::timer through macro. But because namespace boost::timer contains functions that are implemented outside of the header (like std::string format(const cpu_times& times, short places, const std::string& format)) you must rename class boost::timer. So your code will be something like this:

#ifdef  PROG
#define timer   timer_class
#include <boost/progress.hpp>
#undef timer
#endif     //----  PROG  -----

#ifdef  AUTO
#include <boost/timer/timer.hpp>
#endif     //----  AUTO  -----