C++ unique_ptr and polymorphism

Question

Maybe there is the same question but I haven't found it.

I have following code:

class MBase {
    public:
        ~MBase() { cout << "Base destructor\n" << endl; }
};

class MF: public MBase {
    public:
        ~MF() { cout << "MF Destructor" << endl; }
};

class MS: public MBase {
    public:
        ~MS() { cout << "MS Destructor" << endl;}
};

int main() {

    unique_ptr<MBase> ptr1 = unique_ptr<MF>(new MF());
    unique_ptr<MBase> ptr2 = unique_ptr<MS>(new MS());

    return 0;
}

And there is output

Base destructor

Base destructor

Isn't it right? Why derived destructors weren't called? What I have to do to fix that?

when using polymorphism and inheritance in C++, you should have a virtual destructor. — Stephane Rolland, Oct 24 '14 at 14:45

score 0 · Answer 1 · answered Oct 24 '14 at 14:46

0

when using polymorphism and inheritance in C++, you should have a virtual destructor

answered Oct 24 '14 at 14:46

Stephane Rolland

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score 0 · Accepted Answer · edited May 23 '17 at 12:11

0

Polymorphism in C++ requires virtual destructor, so that it would be possible to delete an instance of derived class via a pointer to the base class object.

Long story short - allways declare destructors virtual if class is supposed to be derived from.

When to use virtual destructors?

edited May 23 '17 at 12:11

Community

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1

answered Oct 24 '14 at 14:50

mr.pd

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C++ unique_ptr and polymorphism

2 Answers2