example4_gui_framework.cpp

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#include <iostream>
#include <vector>

class Widget {
public:
    virtual void draw() const = 0;  // Pure virtual function
};

class Button : public Widget {
public:
    void draw() const override {
        std::cout << "Drawing a button." << std::endl;
    }
};

class Slider : public Widget {
public:
    void draw() const override {
        std::cout << "Drawing a slider." << std::endl;
    }
};

void render(const std::vector<Widget*>& widgets) {
    for (const Widget* widget : widgets) {
        widget->draw();  // Calls the appropriate draw() method
    }
}

int main() {
    Button button;
    Slider slider;

    std::vector<Widget*> widgets = {&button, &slider};
    render(widgets);  // Outputs: Drawing a button. Drawing a slider.

    return 0;
}