boost - Cannot iterate a flat map -

i working boost flat_map , trying iterate through it, however, cannot figure out how create iterator.

 my_map = myseg.find<tlsshmmap>("temp_map").first;   //fetch pointer map  tlsshmemallocator alloc_inst (myseg.get_segment_manager());    (boost::container::flat_map<int, tlsstorage, std::less<int>() ,alloc_inst >::const_iterator row = my_map->begin();  row != my_map->end();  ++row)  {     //do stuff   } 

the 'tlsstorage' struct use store data database. boost flat map declared follows somewhere else in code:

boost::container::flat_map tls_temp_map = myseg.construct<tlsshmmap>("temp_map")    (std::less<int>() ,alloc_inst);     //object name 

the code have above not work. here errors, ideas?

src/dbm/dbm_shm_server.cc: in member function 'int redcom::dbm::shmserver::startserver()': src/dbm/dbm_shm_server.cc:353:24: warning: unused variable 'tls_main_map' [-wunused-variable]              tlsshmmap* tls_main_map;                         ^ src/dbm/dbm_shm_server.cc:354:24: warning: unused variable 'tls_temp_map' [-wunused-variable]              tlsshmmap* tls_temp_map;                         ^ src/dbm/dbm_shm_server.cc: in member function 'void redcom::dbm::shmserver::fake_notify()': src/dbm/dbm_shm_server.cc:2023:84: error: value of 'alloc_inst' not usable in constant expression                  (boost::container::flat_map<int, tlsstorage, std::less<int>() ,alloc_inst >::const_iterator row = my_map->begin();                                                                                     ^ src/dbm/dbm_shm_server.cc:2021:40: note: 'alloc_inst' not declared 'constexpr'                 const tlsshmemallocator alloc_inst (myseg.get_segment_manager());                                         ^ src/dbm/dbm_shm_server.cc:2023:95: error: type/value mismatch @ argument 4 in template parameter list 'template<class key, class t, class compare, class allocator> class boost::container::flat_map'                  (boost::container::flat_map<int, tlsstorage, std::less<int>() ,alloc_inst >::const_iterator row = my_map->begin();                                                                                                ^ src/dbm/dbm_shm_server.cc:2023:95: error:   expected type, got 'alloc_inst' src/dbm/dbm_shm_server.cc:2023:113: error: invalid type in declaration before 'row'                  (boost::container::flat_map<int, tlsstorage, std::less<int>() ,alloc_inst >::const_iterator row = my_map->begin();                                                                                                                  ^ src/dbm/dbm_shm_server.cc:2023:113: error: expected ';' before 'row' src/dbm/dbm_shm_server.cc:2023:113: error: 'row' not declared in scope src/dbm/dbm_shm_server.cc:2024:37: error: expected ')' before ';' token                  row != my_map->end();                                      ^ src/dbm/dbm_shm_server.cc:2023:98: warning: unused variable 'const_iterator' [-wunused-variable]                  (boost::container::flat_map<int, tlsstorage, std::less<int>() ,alloc_inst >::const_iterator row = my_map->begin();                                                                                                   ^ src/dbm/dbm_shm_server.cc:2025:19: error: 'row' not declared in scope                  ++row)                    ^ src/dbm/dbm_shm_server.cc:2025:22: error: expected ';' before ')' token                  ++row)                       ^ distcc[31606] error: compile src/dbm/dbm_shm_server.cc on localhost failed scons: *** [debug/build/x86_64-unknown-freebsd9.2/dbm/dbm_shm_server.o] error 1 scons: building terminated because of errors. 

your code appears thoroughly confused. , errors related code shown...^[1]

never mind, have figured out in actual code (shmserver::fake_notify) are declaring allocinst, nearly showed, const:

const tlsshmemallocator alloc_inst (myseg.get_segment_manager()); 

which handsomely explains why loop control variable has invalid type:

error: value of 'alloc_inst' not usable in constant expression error:   expected type, got 'alloc_inst' 

i mean, really, compiler couldn't more explicit it. in case wasn't clear enough added pretty ascii art:

for(flat_map<int, tlsstorage, std::less<int>() ,alloc_inst >::const_iterator row = my_map->begin(); 

so yeah... you're trying pass allocator allocator type argument? instead, use types template arguments. note use of typedefs reduce code clutter:

typedef boost::container::flat_map<     int, tlsstorage, std::less<int>, tlsshmemallocator> shmtable; typedef shmtable::const_iterator shmtableit;  for(shmtableit rowit=my_map->begin(); rowit!=my_map->end(); ++rowit) {      shmtableit::value_type const& row = *rowit;       int id                  = row.first;      tlsstorage const& rowdata = row.second; } 

now of course, c++11 write without typedefs

for(auto rowit=my_map->begin(); rowit!=my_map->end(); ++rowit) {      int id       = rowit->first;      auto& rowdata = rowit->second; } 

or more point:

for(auto const& row : *my_map) {      int id       = row.first;      auto& rowdata = row.second; } 

try reduce on cruft don't overwhelmed code :)

---

^[1] points in case:

• boost::container::flat_map template, declaration cannot possibly correct. suspect have

  tlsshmmap* tls_temp_map; 

  why give false code? that's unrelated?

• in fact, my_map in actual code? or tls_temp_map? or tls_main_map (which don't show, declared , never used...)?