Force an interprocess card using int and string

Question

I have the following code that saves a map to shared memory using boost interprocess

using namespace boost::interprocess; //Shared memory front-end that is able to construct objects //associated with a c-string. Erase previous shared memory with the name //to be used and create the memory segment at the specified address and initialize resources shared_memory_object::remove("MySharedMemory"); try{ managed_shared_memory segment (create_only ,"MySharedMemory" //segment name ,655360); //segment size in bytes //Note that map<Key, MappedType> value_type is std::pair<const Key, MappedType>, //so the allocator must allocate that pair. typedef allocator<char, managed_shared_memory::segment_manager> CharAllocator; typedef basic_string<char, std::char_traits<char> ,CharAllocator> MyShmString; typedef allocator<MyShmString, managed_shared_memory::segment_manager> StringAllocator; typedef int KeyType; typedef std::pair<const int, StringAllocator> ValueType; typedef StringAllocator MappedType; typedef allocator<ValueType, managed_shared_memory::segment_manager> ShmemAllocator; typedef map<KeyType, MappedType, std::less<KeyType>, ShmemAllocator> MyMap; //Initialize the shared memory STL-compatible allocator ShmemAllocator alloc_inst (segment.get_segment_manager()); CharAllocator charallocator (segment.get_segment_manager()); //Construct a shared memory map. //Note that the first parameter is the comparison function, //and the second one the allocator. //This the same signature as std::map constructor taking an allocator MyMap *mymap = segment.construct<MyMap>("MyMap") //object name (std::less<int>() //first ctor parameter ,alloc_inst); //second ctor parameter //Insert data in the map MyShmString mystring(charallocator); mystring = "this is my text"; for(int i = 0; i < 100; ++i){ //mymap[i] = mystring; mymap->insert(std::pair<const int, MappedType>(i, mystring)); } } 

this code does not compile .. it throws the following error

 no matching function for call to 'std::pair<const int, boost::interprocess::allocator<boost::container::basic_string<char, std::char_traits<char>, boost::interprocess::allocator<char, boost::interprocess::segment_manager<char, boost::interprocess::rbtree_best_fit<boost::interprocess::mutex_family, boost::interprocess::offset_ptr<void>, 0ul>, boost::interprocess::iset_index> > >, boost::interprocess::segment_manager<char, boost::interprocess::rbtree_best_fit<boost::interprocess::mutex_family, boost::interprocess::offset_ptr<void>, 0ul>, boost::interprocess::iset_index> > >::pair(int&, main()::MyShmString&)' /usr/include/c++/4.2.1/bits/stl_pair.h:84: note: candidates are: std::pair<_T1, _T2>::pair(const _T1&, const _T2&) [with _T1 = const int, _T2 = boost::interprocess::allocator<boost::container::basic_string<char, std::char_traits<char>, boost::interprocess::allocator<char, boost::interprocess::segment_manager<char, boost::interprocess::rbtree_best_fit<boost::interprocess::mutex_family, boost::interprocess::offset_ptr<void>, 0ul>, boost::interprocess::iset_index> > >, boost::interprocess::segment_manager<char, boost::interprocess::rbtree_best_fit<boost::interprocess::mutex_family, boost::interprocess::offset_ptr<void>, 0ul>, boost::interprocess::iset_index> >] /usr/include/c++/4.2.1/bits/stl_pair.h:80: note: std::pair<_T1, _T2>::pair() [with _T1 = const int, _T2 = boost::interprocess::allocator<boost::container::basic_string<char, std::char_traits<char>, boost::interprocess::allocator<char, boost::interprocess::segment_manager<char, boost::interprocess::rbtree_best_fit<boost::interprocess::mutex_family, boost::interprocess::offset_ptr<void>, 0ul>, boost::interprocess::iset_index> > >, boost::interprocess::segment_manager<char, boost::interprocess::rbtree_best_fit<boost::interprocess::mutex_family, boost::interprocess::offset_ptr<void>, 0ul>, boost::interprocess::iset_index> >] /usr/include/c++/4.2.1/bits/stl_pair.h:69: note: std::pair<const int, boost::interprocess::allocator<boost::container::basic_string<char, std::char_traits<char>, boost::interprocess::allocator<char, boost::interprocess::segment_manager<char, boost::interprocess::rbtree_best_fit<boost::interprocess::mutex_family, boost::interprocess::offset_ptr<void>, 0ul>, boost::interprocess::iset_index> > >, boost::interprocess::segment_manager<char, boost::interprocess::rbtree_best_fit<boost::interprocess::mutex_family, boost::interprocess::offset_ptr<void>, 0ul>, boost::interprocess::iset_index> > >::pair(const std::pair<const int, boost::interprocess::allocator<boost::container::basic_string<char, std::char_traits<char>, boost::interprocess::allocator<char, boost::interprocess::segment_manager<char, boost::interprocess::rbtree_best_fit<boost::interprocess::mutex_family, boost::interprocess::offset_ptr<void>, 0ul>, boost::interprocess::iset_index> > >, boost::interprocess::segment_manager<char, boost::interprocess::rbtree_best_fit<boost::interprocess::mutex_family, boost::interprocess::offset_ptr<void>, 0ul>, boost::interprocess::iset_index> > >&) 

difference if

 ::pair(int&, main()::MyShmString&) 

so i guess

  mymap->insert(std::pair<const int, MappedType>(i, mystring)); 

- this is not the right way ... since I insert into the card, if the error is there .. what else is the error?

Answer 1

Of course, value_type:

 typedef std::pair<const int, MyShmString > ValueType; 

not

 typedef std::pair<const int, StringAllocator> ValueType; 

And similarly:

 typedef MyShmString MappedType; 

not

 typedef StringAllocator MappedType; 

Answer 2

Your types are different, is it intentional? MyShmString does not match MappedType - maybe you should change the following line:

 typedef StringAllocator MappedType; 

to

 typedef MyShmString MappedType;