将派生类指针的矢量传递给线程

Question

I have a Base class with Derived1 and Derived2 derived classes and a Consumer class.

I want to create a vector of Base pointers with the two derived class objects to then pass to the consumer class so it can get derived class details using

pointervec.at(0).i

I've been stuck on this for ages and cannot get it to work. This is a simplified version of what I have. I'm concerned about the syntax around creating the vector, passing it to the thread and accessing different indexes.

#include<vector>
#include<thread>
#include<iostream>

using namespace std;

class Base
{
public:
    Base() {};
    void dosomething() {cout<<i<<endl;}
    int i;
};

class Derived1 : public Base
{
public:
    Derived1() {i = 5;}
};

class Derived2 : public Base
{
public:
    Derived2() {i = 10;}
};

class Consumer
{
public:
    Consumer();
    void dostuff( vector<Base> &pointervec) {cout<<5<<endl;}
};

int main( int argc, char ** argv )
{
    Derived1 derived1;
    Derived2 derived2;

    vector<Base*>pointervec;
    pointervec.push_back(&derived1);
    pointervec.push_back(&derived2);

    std::thread t1(&Derived1::dosomething, &derived1);
    std::thread t2(&Derived2::dosomething, &derived2);
    std::thread t3(&Consumer::dostuff, ref(pointervec));

    t1.join();
    t2.join();
    t3.join();
}

Answer 1

To make your example work, there are a few mistakes that need to be corrected.

1. As Consumer::doStuff is a non-static member function, you need an instance of Consumer to run it on.
2. Because of above, Consumer needs a defined constructor
3. The signature of doStuff needs to take a (reference to a) vector of Base pointers, not Base objects
4. Thread t3 needs said instance of Consumer as its first forwarded parameter (to provide the this parameter.

Final working code:

#include<vector>
#include<thread>
#include<iostream>

using namespace std;

class Base
{
public:
    Base() {};
    void dosomething() {cout<<i<<endl;}
    int i;
};

class Derived1 : public Base
{
public:
    Derived1() {i = 5;}
};

class Derived2 : public Base
{
public:
    Derived2() {i = 10;}
};

class Consumer
{
public:
    Consumer() {}
    void dostuff( vector<Base*> &pointervec) {cout<<pointervec.at(0)->i<<endl;}
};

int main( int argc, char ** argv )
{
    Derived1 derived1;
    Derived2 derived2;

    Consumer c;
    vector<Base*>pointervec;
    pointervec.push_back(&derived1);
    pointervec.push_back(&derived2);

    std::thread t1(&Derived1::dosomething, &derived1);
    std::thread t2(&Derived2::dosomething, &derived2);
    std::thread t3(&Consumer::dostuff, &c, ref(pointervec));

    t1.join();
    t2.join();
    t3.join();
}