cmp.cpp

#include <iostream>
#include <utility>

namespace dst {
        template<class T>
                class cmp_default {
                        public:
                                bool operator()( const T& left, const T& right) { return left < right; };
                };
 
        template<class T, class C>
                class heap {
                        public:
                                heap ( C cmp_function = cmp_default<T>() );
                                ~heap ( void ) = default;
                        //private:
                                C cmp_function;
                };
 
        template<class T, class C>
                heap<T, C>::heap ( C cmp_function) {
                        this->cmp_function = cmp_function;
 
                        return;
                }

    template<class T, class C>
    heap(C) -> heap<T, C>;

}
 
bool is_less(int l, int r) {
        return l <= r;
}
 

int main() {
    
    //std::pair<int> p(1, 2.0);

    dst::heap<int> heap = is_less;
        //dst::heap<int> heap_int;
 
        //std::cout << heap->cmp_function(5, 5);// << ' ' << heap_int.cmp_function(5, 5) << '\n';
 
}