Effective C++ #9 before

main.cpp

#include <iostream>
#include <memory>

class Base {
public:
    Base() { init(); }
    virtual void log() const = 0;
private:
    void init() {
        std::cout << "do something" << std::endl;
        log();
    }
};

class Derived : public Base {
public:
    Derived() {};
    virtual void log() const {}
};

int main(void){
    std::unique_ptr<Derived> ptr = std::make_unique<Derived>();
    return 0;
}