How to create a thread by a child member function

Question

I have a IBase class and a Child class. I need to call different proc function in different child class. I'm not sure which form below is actually right, maybe neither XD.

• Form 1: Exactly I don't want my IBase have any non-virtual function.
• Form 2: There's a strange expression &IBase::proc could make some misunderstanding.

class IBase
{
public:
    virtual void proc() = 0;

    auto createBind()
    {
        return bind(&IBase::proc, this);
    }
};
class Child :public IBase
{
public:
    void proc() override
    {
        cout << "Hello World" << endl;
    }
};
int main()
{
    IBase* pointer = new Child;

        //form 1
    thread th(pointer->createBind());
    th.join();

        //form 2
    thread th2(&IBase::proc, pointer);
    th2.join();

    cout << "Finish" << endl;
    return 0;
}

I'm wondering how do you guys solve this circumstance in a real project.

Answer 1

I would use form 3 :-) :

thread* th3 = pointer->start();
th3->join();

with start in IBase as:

thread* start()
{
    thread* t = new thread(createBind());

    return t;
}

Which would in my opinion hide more details of the implementation and give the caller the API he expects (start a thread).

Answer 2

The most idiomatic and robust way is probably this

std::thread t([=]{pointer->proc();});

No bind, no extraneous helper member function, no weird syntax with redundant mention of the class name.