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c++stdstdthread

What's the difference between ( this ) and ( std::ref(*this) )

I used to create a thread in this way

std::thread(&A::Func, this);

But I find there's another way

std::thread(&A::Func, std::ref(*this));

What's the difference between them?

Solution

  • In the context of launching a thread running a member function of a class A, those calls are equivalent.

    The first is like

    void compiler_created_on_new_thread(A * a) { a->Func(); }

    The second is like

    void compiler_created_on_new_thread(A & a) { a.Func(); }

    If instead A were a namespace, they would be distinguishable

    namespace A {
    void Func(Thing *) { std::cout << "pointer"; }
    void Func(Thing &) { std::cout << "reference"; }
}

    The first would display "pointer" and the second "reference"