Add Multiple Dispatch post

content/posts/2022-11-02-multiple-dispatch-in-c++/index.md

@@ -122,6 +122,8 @@ struct Asteroid;
 struct Spaceship;
 
 struct SpaceObject {
+    virtual ~SpaceObject() = default;
+
     // Only used to kick-start the double-dispatch process
     virtual void collide_with(SpaceObject& other) = 0;
 
@@ -130,32 +132,24 @@ struct SpaceObject {
     virtual void collide_with(Spaceship& other) = 0;
 };
 
-struct Asteroid {
+struct Asteroid : SpaceObject {
     void collide_with(SpaceObject& other) override {
         // `*this` is an `Asteroid&` which kick-starts the double-dispatch
         other.collide_with(*this);
     };
 
-    void collide_with(Asteroid& other) override {
+    void collide_with(Asteroid& other) override { /* Asteroid/Asteroid */ };
-        // Asteroid/Asteroid
+    void collide_with(Spaceship& other) override { /* Asteroid/Spaceship */ };
-    };
-    void collide_with(Spaceship& other) override {
-        // Asteroid/Spaceship
-    };
 };
 
-struct Spaceship {
+struct Spaceship : SpaceObject {
     void collide_with(SpaceObject& other) override {
         // `*this` is a `Spaceship&` which kick-starts the double-dispatch
         other.collide_with(*this);
     };
 
-    void collide_with(Asteroid& other) override {
+    void collide_with(Asteroid& other) override { /* Spaceship/Asteroid */ };
-        // Spaceship/Asteroid
+    void collide_with(Spaceship& other) override { /* Spaceship/Spaceship */ };
-    };
-    void collide_with(Spaceship& other) override {
-        // Spaceship/Spaceship
-    };
 };
 
 void collide(SpaceObject& first, SpaceObject& second) {