boost interprocess map with int and string - c++

Question

I have the following code that saves a map into 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>'s 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's 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 doesnt 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> > >&)
the difference if
::pair(int&, main()::MyShmString&)
so i am guessing
mymap->insert(std::pair<const int, MappedType>(i, mystring));
is not the correct way to go.. so how should i insert into the map, if the error is there.. else what is the error?

Answer 1

Surely the value_type is:
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 that intentional? MyShmString is not the same as MappedType - may be you ought to change the following line:
typedef StringAllocator MappedType;
to
typedef MyShmString MappedType;