Discussion: A Destructive Relationship
Execute the code to understand the output and gain insights into destructors and virtual functions.
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Run the output
Now, it’s time to execute the code and observe the output.
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#include <iostream>#include <memory>struct Widget{virtual void draw() { std::cout << "Widget draw\n"; }virtual ~Widget() { std::cout << "Widget destructor\n"; }};struct Button : public Widget{void draw() override { std::cout << "Button draw\n"; }~Button() override { std::cout << "Button destructor\n"; }};int main(){std::unique_ptr<Widget> widget = std::make_unique<Button>();widget->draw();}
Understanding the output
When we call draw(), the program only prints Button draw. But when unique_ptr goes out of scope, and the destructor is called, the program prints both Button destructor and Widget destructor. Why is that?
Virtual functions
A common technique for dynamic polymorphism is using virtual functions. We ...