std::vector< std::string> a;

// ...fill it

// WRONG !!!

get_log().ts() << "Here are the strings from array a:\n";

// ... note: temporary returned by get_log()

//    has been destructed here

std::vector< std::string>::const_iterator

    first = a.begin(), last = a.end();

while ( first != last)

{

    get_log().ts() << *first++ << " ";

    // ... note: temporary returned by get_log()

    //    has been destructed here

}

The above should become:

std::vector< std::string> a;

// ...fill it

thread_safe_log log = get_log();

log.ts() << "Here are the strings from array a:\n";

std::vector< std::string>::const_iterator

    first = a.begin(), last = a.end();

while ( first != last)

    log.ts() << *first++ << " ";

log << std::endl;