c++ - Assigning a new value to a iterator of a intrusive container -

while working boost intrusive container splay_set, have reset local iterator member variables. please see sample code below -

#include <boost/intrusive/splay_set.hpp>  using namespace boost::intrusive;  class obj {     public:         obj(){};         ~obj(){};          boost::intrusive::list_member_hook<boost::intrusive::link_mode<boost::intrusive::normal_link> > m_memberhook;     private:         int a; };  typedef splay_set<obj, compare<greater<obj> >, member_hook<obj,                  splay_set_member_hook<boost::intrusive::link_mode<boost::intrusive::normal_link> >,                 &obj::m_memberhook> > storagesset; typedef storagesset::iterator   storagessetiter;  class storage {     public:          bool init(storagesset& sset)         {             // error: "no match operator= in ..."             m_curiter = sset.begin();  ////<<<<------------- how set new iterator             m_enditer = sset.end();    ////<<<<------------- how set new iterator         }      protected:          storagessetiter     m_curiter;         storagessetiter     m_enditer; }; 

intrusive container doesn't support assignment suppose. cannot initialize splay_set iterator via member initializer list. there limited example on boost , other site. none gives clear answer question.

my question should assign new value splay_set iterator (and in general sense intrusive container.)

the reason why const_iterators because modifying fields may break container invariants.

e.g. when building set across elements of struct { int key; std::string value; };, modifying key field through iterator lead [undefined behaviour]

the clean way update things first remove, reinsert modified item.

if hurts performance badly

1. reconsider design (consider mutable members non-key fields, consider including non-key data reference)
2. punch hole in abstraction using const_cast<> cast away const. danger don't pass reference other party, because break container invariants since might not know leave key fields alone