Module Partitions

// geometry.cppm - Primary module interface
export module geometry;
export import :shapes;    // Re-export shapes partition
export import :utils;     // Re-export utils partition
// geometry-shapes.cppm - Shapes partition
export module geometry:shapes;
export struct Point {
    double x, y;
};
export struct Circle {
    Point center;
    double radius;
};
export struct Rectangle {
    Point topLeft;
    double width, height;
};
// geometry-utils.cppm - Utils partition
export module geometry:utils;
import :shapes;
export double distance(Point a, Point b) {
    double dx = b.x - a.x;
    double dy = b.y - a.y;
    return std::sqrt(dx*dx + dy*dy);
}
export double area(const Circle& c) {
    return 3.14159 * c.radius * c.radius;
}
export double area(const Rectangle& r) {
    return r.width * r.height;
}
// main.cpp
import geometry;
#include <iostream>
int main() {
    Circle c{{0, 0}, 5};
    Rectangle r{{0, 0}, 10, 20};
    
    std::cout << "Circle area: " << area(c) << std::endl;
    std::cout << "Rectangle area: " << area(r) << std::endl;
    return 0;
}