refactor(Ex22): apply template method to Timer

Rename the virtual tick() override in PelicanTimer to doExpired()
and give the base Timer class a non-virtual tick() that checks for
expiration and dispatches to doExpired(). The exercise starting
point now matches SolutionEx22.

Co-authored-by: Qwen 3.8 27B <qwen3.8_27b-q3_k_xl@lmstudio.local>

cmat/Ex22/PelicanTimer.cpp

@@ -4,8 +4,6 @@
 
 PelicanTimer::PelicanTimer(Pelican &target, TargetFunc targetFunc) : myTarget(target), myTargetFunc(targetFunc) {}
 
-void PelicanTimer::tick() {
-    if (isExpired()) {
+void PelicanTimer::doExpired() {
     (myTarget.*myTargetFunc)();
 }
-}

cmat/Ex22/PelicanTimer.h

@@ -17,8 +17,7 @@ class PelicanTimer : public Timer {
 
     PelicanTimer(Pelican &target, TargetFunc targetFunc);
 
-    // TODO: Rename this function to doExpired. The parameters and return type are unchanged.
-    virtual void tick();
+    void doExpired();
 
   private:
     Pelican &myTarget;

cmat/Ex22/Timer.cpp

@@ -7,6 +7,12 @@ void Timer::timeoutRequest(int seconds) { timeToGo = seconds; }
 
 Timer::Timer() : timeToGo(-1) { TimerSet::Instance().addATimer(this); }
 
+void Timer::tick() {
+    if (isExpired()) {
+        doExpired();
+    }
+}
+
 bool Timer::isExpired() {
     if (timeToGo > 0) {
         if (--timeToGo == 0) {

cmat/Ex22/Timer.h

@@ -15,7 +15,10 @@ class Timer {
 
     void timeoutRequest(int seconds);
 
-    virtual void tick() = 0;
+   void tick();
+
+  private:
+    virtual void doExpired() = 0;
 
   protected:
     bool isExpired();