c++ - Template Class wrong copy constructor called -


solution

to avoid problem std::auto_ptr 1 can switch boost::shard_ptr or c++11 std::shared_ptr.

i error wrong copy constructor called in template class:

mpinetworkcode.hpp: error: no matching function call  mpilib::mpinode<double>::mpinode(mpilib::mpinode<double>)  mpinode.hpp: note: candidate is:  mpilib::mpinode<double>::mpinode(mpilib::mpinode<double>&)

here code lines result in error.

int mpinetwork<weightvalue>::addnode(const algorithminterface<weightvalue>& alg,     nodetype nodetype) {      mpinode<weightvalue> node = mpinode<weightvalue>(alg, nodetype,            tempnodeid, _nodedistribution, _localnodes);     _localnodes.insert(std::make_pair(tempnodeid, node)); }

what wrong code, , why wrong copy constructor called? in previous version of class without templates worked fine.

here header of related classes. template implementation in header file.

here mpinetwork:

template <class weightvalue> class mpinetwork: private boost::noncopyable {  public:      explicit mpinetwork();      ~mpinetwork();      /**      * adds new node network      * @param alg algorithm of actual node      * @param nodetype type of node      * @return returns nodeid of generated node      */     int addnode(const algorithminterface<weightvalue>& alg, nodetype nodetype);  //lot of code  };

and second mpinode, default copy constructor should called:

template <class weight> class mpinode { public:     /**      * constructor      * @param algorithm algorithm algorithm node should contain      * @param nodetype nodetype type of node      * @param nodeid nodeid id of node      * @param nodedistribution node distribution.      * @param localnode local nodes of processor      */     explicit mpinode(const algorithminterface<weight>& algorithm, nodetype nodetype,             nodeid nodeid,             const boost::shared_ptr<utilities::nodedistributioninterface>& nodedistribution,             const std::map<nodeid, mpinode<weight> >& localnode);      virtual ~mpinode();      time evolve(time time);      void configuresimulationrun(const simulationrunparameter& simparam);      void addprecursor(nodeid nodeid, const weight& weight);      void addsuccessor(nodeid nodeid);      nodestate getstate() const;      void setstate(nodestate state);      void receivedata();      void sendownstate();  private:      void waitall();      std::vector<nodeid> _precursors;      std::vector<weight> _weights;      std::vector<nodeid> _successors;      std::auto_ptr<algorithminterface<weight> > _algorithm;      nodetype _nodetype;      nodeid _nodeid;      const std::map<nodeid, mpinode>& _reflocalnodes;      boost::shared_ptr<utilities::nodedistributioninterface> _nodedistribution;      nodestate _state;      std::vector<nodestate> _precursorstates;      std::vector<boost::mpi::request> _mpistatus; };  template<class weight> mpinode<weight>::mpinode(const algorithminterface<weight>& algorithm, nodetype nodetype,         nodeid nodeid,         const boost::shared_ptr<utilities::nodedistributioninterface>& nodedistribution,         const std::map<nodeid, mpinode>& localnode) :         _algorithm(algorithm.clone()), _nodetype(nodetype), _nodeid(nodeid), _nodedistribution(                 nodedistribution), _reflocalnodes(localnode) {  }

your problem caused member:

std::auto_ptr<algorithminterface<weight> > _algorithm;

std::auto_ptr's copy constructor doesn't copy, transfers ownership. because of takes non-const reference argument, not const reference.

this means when compiler comes generate copy constructor mpinode specialization cannot generate copy constructor takes const reference mpinode, can generate 1 takes non const reference.

in initialization, temporary mpinode<weightvalue> cannot bind non-const reference parameter generated copy constructor requires.

mpinode<weightvalue> node = mpinode<weightvalue>(alg, nodetype,        tempnodeid, _nodedistribution, _localnodes);

how fix depends on design. might supplying user-defined copy constructor takes const reference , clones _algorithm member correct approach.


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