具有自定义比较器的STL priority_queue继承不起作用

Question

我想从STL优先级队列继承一些附加功能，例如：从而允许移除。但当我使用自定义比较器时，我很难做到这一点。MWE:

#include <queue>
template<typename T, class Container=std::vector<T>, class Compare=std::less<typename Container::value_type>> 
class custom_priority_queue : public std::priority_queue<T, Container, Compare>
{
public:
// My additional functions here.
};
int main()
{
auto pq_comp = [](const int& a, const int& b) { return a <= b; };
std::priority_queue<int, std::vector<int>, decltype(pq_comp)> pq(pq_comp); // works
custom_priority_queue<int> pq_custom; // works
custom_priority_queue<int, std::vector<int>, decltype(pq_comp)> pq_custom2(pq_comp); // Error
return 0;
}

错误为：

main.cpp: In function ‘int main()’:
main.cpp:15:87: error: no matching function for call to ‘custom_priority_queue, main():: >::custom_priority_queue(main()::&)’
15 |     custom_priority_queue<int, std::vector<int>, decltype(pq_comp)> pq_custom2(pq_comp); // Error
|                                                                                       ^
main.cpp:4:7: note: candidate: ‘custom_priority_queue, main():: >::custom_priority_queue(const custom_priority_queue, main():: >&)’
4 | class custom_priority_queue : public std::priority_queue<T, Container, Compare>
|       ^~~~~~~~~~~~~~~~~~~~~
main.cpp:4:7: note:   no known conversion for argument 1 from ‘main()::’ to ‘const custom_priority_queue, main():: >&’
main.cpp:4:7: note: candidate: ‘custom_priority_queue, main():: >::custom_priority_queue(custom_priority_queue, main():: >&&)’
main.cpp:4:7: note:   no known conversion for argument 1 from ‘main()::’ to ‘custom_priority_queue, main():: >&&’

Answer 1

构造函数不是自动继承的，所以您的类可能缺少任何构造函数，除了隐式声明的构造函数。

您可以显式继承基类的所有构造函数：

template<typename T, class Container=std::vector<T>, class Compare=std::less<typename Container::value_type>> 
class custom_priority_queue : public std::priority_queue<T, Container, Compare>
{
// inherit constructors
using priority_queue::priority_queue;
public:
// My additional functions here.
};