如何在创建对象时传递自定义比较器函数，以及如何在C++的自定义父类中使用它？

bool compareByAge(const MyClass& obj1, const MyClass& obj2) {
    return obj1.age < obj2.age;
}

#include <set>
#include <functional>

class MyClass {
public:
    int age;
    // other members and methods
};

int main() {
    std::set<MyClass, std::function<bool(const MyClass&, const MyClass&)>> mySet(compareByAge);

    // 添加对象到mySet

    // 使用自定义比较器函数进行排序
    for (const auto& obj : mySet) {
        // 遍历排序后的对象
    }

    return 0;
}

#include <iostream>

class Parent {
public:
    virtual bool compare(const Parent& other) const = 0;
    // other members and methods
};

class Child : public Parent {
private:
    int value;
public:
    bool compare(const Parent& other) const override {
        const Child& otherChild = dynamic_cast<const Child&>(other);
        return value < otherChild.value;
    }
    // other members and methods
};

int main() {
    Parent* parent1 = new Child();
    Parent* parent2 = new Child();

    if (parent1->compare(*parent2)) {
        std::cout << "parent1 is less than parent2" << std::endl;
    } else {
        std::cout << "parent1 is greater than or equal to parent2" << std::endl;
    }

    delete parent1;
    delete parent2;

    return 0;
}