c++ - Custom comparator (ordering) as a (multi)map ordering parameter? -

my question in many ways similar one: pass custom comparator through function, tried solution proposed there, , not work.

in nutshell, have method keeps several sorted structures , performs several comparisons, on elements of type int, all using same ordering. ordering determined when method called.

the intended call like: myfunction(std::greater<int>());

first, tried declaring function as: void myfunction(binary_operator<int, int, bool> order); but, per this explanation, binary_function not suited act base class in function calls.

finally, i tried suggestion this answer (and many other sites), suggested using templates. but, still can not code compile.

the minimal non-working example:

template <typename comparator>  void myfunction(comparator order){    if (order(1,2)){       // stuff       // compiles ok   }    std::vector <int> vectosort;   // ... initialize   std::sort(vectosort.begin(), vectosort.end(), order); // works   // compiles ok    std::multimap <int, int, order > boundary;   // starts kicking, screaming , shouthing } 

and compile error get:

error: type/value mismatch @ argument 3 in template parameter list ‘template class std::multimap’ error: expected type, got ‘order’

i figured same trick should work both. not. (edit: can see type/object problem now)

can please explain happening here , how the multimap to use ordering passed function argument?

ps: not using boost project.

it should declared follows:

std::multimap <int, int, comparator> boundary(order);                          ^^^^^^^^^^ 

as comments say, need provide type not object. these docs construct multimap give examples.