Initializing multiset with custom comparison function in C++

Question

Consider following comparison function:

bool compare(std::shared_ptr &lhs, std::shared_ptr &rhs){
   return lhs->val         


        

Answer 1

decltype(compare)* in the template parameter specifies the type of the comparator. It doesn't tell which function is to be used - whether is it compare, foo, bar or something else. Hence the constructor parameter.