[Boost-bugs] [Boost C++ Libraries] #4617: Use of stringstreams in numeric/ublas/io

Subject: [Boost-bugs] [Boost C++ Libraries] #4617: Use of stringstreams in numeric/ublas/io
From: Boost C++ Libraries (noreply_at_[hidden])
Date: 2010-09-01 14:18:14

#4617: Use of stringstreams in numeric/ublas/io
-----------------------------------------+----------------------------------
 Reporter:  Kostya <seraphym@…>          |       Owner:  guwi17      
     Type:  Bugs                         |      Status:  new         
Milestone:  To Be Determined             |   Component:  uBLAS       
  Version:  Boost 1.44.0                 |    Severity:  Optimization
 Keywords:                               |  
-----------------------------------------+----------------------------------
 Not 100% sure it is a bug, but use of additional string streams seems a
 bit odd.

 {{{
     template<class E, class T, class ME>
     // BOOST_UBLAS_INLINE This function seems to be big. So we do not let
 the compiler inline it.
     std::basic_ostream<E, T> &operator << (std::basic_ostream<E, T> &os,
                                            const matrix_expression<ME> &m)
 {
         typedef typename ME::size_type size_type;
         size_type size1 = m ().size1 ();
         size_type size2 = m ().size2 ();
         std::basic_ostringstream<E, T, std::allocator<E> > s;
         s.flags (os.flags ());
         s.imbue (os.getloc ());
         s.precision (os.precision ());
         s << '[' << size1 << ',' << size2 << "](";
         if (size1 > 0) {
             s << '(' ;
             if (size2 > 0)
                 s << m () (0, 0);
             for (size_type j = 1; j < size2; ++ j)
                 s << ',' << m () (0, j);
             s << ')';
         }
         for (size_type i = 1; i < size1; ++ i) {
             s << ",(" ;
             if (size2 > 0)
                 s << m () (i, 0);
             for (size_type j = 1; j < size2; ++ j)
                 s << ',' << m () (i, j);
             s << ')';
         }
         s << ')';
         return os << s.str ().c_str ();
     }
 }}}

 why do we create stringstream 's' and serialize everything in memory and
 only then pump it to 'os'?

-- 
Ticket URL: <https://svn.boost.org/trac/boost/ticket/4617>
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