How to prevent std::function to bool conversion in c++ function overloading?

Question

How to prevent std::function to bool conversion in C++ function overloading? such as

class Object final {
    
public:
    Object(bool boolean) : type_(22)  {}  //#1
    Object(const std::function<int(int*, int)>  value) : type_(11) {}  //#2
    
    int rettype() { return type_; };
    
private:
    int type_;
};


int Println(int *args, int nargs) {
  printf("Println\n");
  return 0;
}

int main() {
    cout << Object(Println).rettype() << endl; // 22
    cout << Object(std::function<int(int*, int)>(Println)).rettype() << endl; // 11
}

I want to call #2 through Object(Println) instead of Object(std::function<int(int*, int)>(Println))，but the result is that #1 is called

How should I achieve this?

Answer 1

The modern C++ solution here would be Object::Object(std::invocable<int*, int> auto f)

You don't care exactly what the type of f is - that's clear from the fact that you consider std::function<int(int*, int)> and int(*)(int*, int)> interchangeable. std::invocable is slightly more general than that: it says anything callable is also OK. A lambda would also work.