为什么在 protobuf 消息上调用方法会抛出一个称为错误的纯虚方法？

Question

I'm trying to use the Google Protobuf library and I want to store a bunch of different message types together in a container and get their names as I pull them out of the container. I think I can use the interface type google::protobuf::Message to do this. Here is what I have so far.

#include <iostream>
#include "addressbook.pb.h"

using namespace std;

int main(void) {
  vector<shared_ptr<google::protobuf::Message>> vec;
  
  {
    tutorial::AddressBook address_book;
    vec.push_back(shared_ptr<google::protobuf::Message>(&address_book));
  }

  cout << "Typename is " << vec.back()->GetTypeName() << endl;
  return 0;
}

Calling GetTypeName throws the following error:

pure virtual method called
terminate called without an active exception
Aborted (core dumped)

Note this is me playing around with the tutorial found here:https://developers.google.com/protocol-buffers/docs/cpptutorial

Answer 1

address_book is on the stack it will be deleted when it goes out of scope, no smart pointer can prevent that.

Just create your book with std::make_shared , that will be on the heap and its lifetime will be managed from the std::shared_ptr .