CODEWITHSUNDEEP
c++c++11
jkbz64
jkbz64

Reputation: 180

Invoke base class function as derived

Is there any way to call base class method from virtual function as derived class, not as base one? Example code:

class A
{
public:
    virtual void a() = 0;
    void print() { std::cerr << typeid(decltype(*this)).name(); };
};

class B : public A
{
public:
    virtual void a() { print(); }
};

int main() 
{
    B b;
    b.a(); //prints 1A, I want it to print 1B, is it even possible?
}

Upvotes: 7

Views: 157

Answers (1)

Barry
Barry

Reputation: 302977

Just drop the decltype:

void print() { std::cerr << typeid(*this).name(); };

this always points to an instance of the class whose member function its in. this inside A is always an A*. So typeid(decltype(*this)) always gives you A.

On the other hand, typeid(*this) will lookup runtime type information, which will determine that this is really a B (because A is a polymorphic type).

Upvotes: 14

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