Abstract Unit class

src/Hero.cpp

@@ -17,3 +17,7 @@ void Hero::draw(QGraphicsScene *scene) const {
 Unit *Hero::clone() const {
     return new Hero(*this);
 }
+
+bool Hero::isAlive() const { return true; }
+bool Hero::isToBeJunked() const { return false; }
+void Hero::doCrash() {}

src/Hero.h

@@ -18,7 +18,9 @@ public:
      * Draws this hero onto the given QGraphicsScene.
      */
     void draw(QGraphicsScene *scene) const override;
-
+    bool isAlive() const override;
+    bool isToBeJunked() const override;
+    void doCrash() override;
 };
 
 #endif // HERO_H

src/Unit.cpp

@@ -59,7 +59,4 @@ void Unit::checkBounds() {
 }
 
 // Default implementation
-bool Unit::isAlive() const { return true; }
-bool Unit::isToBeJunked() const { return false; }
-void Unit::doCrash() {}
-void Unit::draw(QGraphicsScene *) const {}
+

src/Unit.h

@@ -57,10 +57,10 @@ public:
     */
     double distanceTo(const Unit& u) const;
 
-    virtual bool isAlive() const;
-    virtual bool isToBeJunked() const;
-    virtual void doCrash();
-    virtual void draw(QGraphicsScene *scene) const;
+    virtual bool isAlive() const = 0;
+    virtual bool isToBeJunked() const = 0;
+    virtual void doCrash() = 0;
+    virtual void draw(QGraphicsScene *scene) const = 0;
 private:
     int x;  // x position of this unit
     int y;  // y position of this unit