From 73395fe6f4cab9463d3bcba77ef81b40e4000407 Mon Sep 17 00:00:00 2001
From: John Wellbelove <john.wellbelove@etlcpp.com>
Date: Fri, 2 Aug 2024 10:36:13 +0100
Subject: [PATCH] Updated C++03 observer class to accept void parameter
 notification types

---
 include/etl/observer.h | 125 ++++++++++++++++++++++++++---------------
 test/test_observer.cpp |  76 ++-----------------------
 2 files changed, 85 insertions(+), 116 deletions(-)

diff --git a/include/etl/observer.h b/include/etl/observer.h
index 32eee70ec..eda17dfa7 100644
--- a/include/etl/observer.h
+++ b/include/etl/observer.h
@@ -294,19 +294,23 @@ namespace etl
     Observer_List observer_list;
   };
 
-#if ETL_USING_CPP11 && !defined(ETL_OBSERVER_FORCE_CPP03_IMPLEMENTATION)
+#if ETL_USING_CPP11
+  template <typename... TTypes>
+  class observer;
 
   //*****************************************************************
   /// The observer class for N types.
   ///\ingroup observer
   //*****************************************************************
-  template <typename T1, typename... Types>
-  class observer : public observer<T1>, public observer<Types...>
+  template <typename T1, typename... TRest>
+  class observer<T1, TRest...> : public observer<T1>, public observer<TRest...>
   {
   public:
 
+    ETL_STATIC_ASSERT((!etl::has_duplicates<T1, TRest...>::value), "Observer has duplicate notification types");
+
     using observer<T1>::notification;
-    using observer<Types...>::notification;
+    using observer<TRest...>::notification;
   };
 
   //*****************************************************************
@@ -351,18 +355,26 @@ namespace etl
             typename T6  = void,
             typename T7  = void,
             typename T8  = void>
-  class observer
+  class observer : public observer<T1>
+                 , public observer<T2>
+                 , public observer<T3>
+                 , public observer<T4>
+                 , public observer<T5>
+                 , public observer<T6>
+                 , public observer<T7>
+                 , public observer<T8>
   {
   public:
     virtual ~observer() {}
-    virtual void notification(T1) = 0;
-    virtual void notification(T2) = 0;
-    virtual void notification(T3) = 0;
-    virtual void notification(T4) = 0;
-    virtual void notification(T5) = 0;
-    virtual void notification(T6) = 0;
-    virtual void notification(T7) = 0;
-    virtual void notification(T8) = 0;
+
+    using observer<T1>::notification;
+    using observer<T2>::notification;
+    using observer<T3>::notification;
+    using observer<T4>::notification;
+    using observer<T5>::notification;
+    using observer<T6>::notification;
+    using observer<T7>::notification;
+    using observer<T8>::notification;
   };
 
   //*********************************************************************
@@ -376,18 +388,24 @@ namespace etl
             typename T5,
             typename T6,
             typename T7>
-  class observer<T1, T2, T3, T4, T5, T6, T7>
+  class observer<T1, T2, T3, T4, T5, T6, T7> : public observer<T1>
+                                             , public observer<T2>
+                                             , public observer<T3>
+                                             , public observer<T4>
+                                             , public observer<T5>
+                                             , public observer<T6>
+                                             , public observer<T7>
   {
   public:
 
     virtual ~observer() {}
-    virtual void notification(T1) = 0;
-    virtual void notification(T2) = 0;
-    virtual void notification(T3) = 0;
-    virtual void notification(T4) = 0;
-    virtual void notification(T5) = 0;
-    virtual void notification(T6) = 0;
-    virtual void notification(T7) = 0;
+    using observer<T1>::notification;
+    using observer<T2>::notification;
+    using observer<T3>::notification;
+    using observer<T4>::notification;
+    using observer<T5>::notification;
+    using observer<T6>::notification;
+    using observer<T7>::notification;
   };
 
   //*********************************************************************
@@ -400,17 +418,22 @@ namespace etl
             typename T4,
             typename T5,
             typename T6>
-  class observer<T1, T2, T3, T4, T5, T6>
+  class observer<T1, T2, T3, T4, T5, T6> : public observer<T1>
+                                         , public observer<T2>
+                                         , public observer<T3>
+                                         , public observer<T4>
+                                         , public observer<T5>
+                                         , public observer<T6>
   {
   public:
 
     virtual ~observer() {}
-    virtual void notification(T1) = 0;
-    virtual void notification(T2) = 0;
-    virtual void notification(T3) = 0;
-    virtual void notification(T4) = 0;
-    virtual void notification(T5) = 0;
-    virtual void notification(T6) = 0;
+    using observer<T1>::notification;
+    using observer<T2>::notification;
+    using observer<T3>::notification;
+    using observer<T4>::notification;
+    using observer<T5>::notification;
+    using observer<T6>::notification;
   };
 
   //*********************************************************************
@@ -422,16 +445,20 @@ namespace etl
             typename T3,
             typename T4,
             typename T5>
-  class observer<T1, T2, T3, T4, T5>
+  class observer<T1, T2, T3, T4, T5> : public observer<T1>
+                                     , public observer<T2>
+                                     , public observer<T3>
+                                     , public observer<T4>
+                                     , public observer<T5>
   {
   public:
 
     virtual ~observer() {}
-    virtual void notification(T1) = 0;
-    virtual void notification(T2) = 0;
-    virtual void notification(T3) = 0;
-    virtual void notification(T4) = 0;
-    virtual void notification(T5) = 0;
+    using observer<T1>::notification;
+    using observer<T2>::notification;
+    using observer<T3>::notification;
+    using observer<T4>::notification;
+    using observer<T5>::notification;
   };
 
   //*********************************************************************
@@ -442,15 +469,18 @@ namespace etl
             typename T2,
             typename T3,
             typename T4>
-  class observer<T1, T2, T3, T4>
+  class observer<T1, T2, T3, T4> : public observer<T1>
+                                 , public observer<T2>
+                                 , public observer<T3>
+                                 , public observer<T4>
   {
   public:
 
     virtual ~observer() {}
-    virtual void notification(T1) = 0;
-    virtual void notification(T2) = 0;
-    virtual void notification(T3) = 0;
-    virtual void notification(T4) = 0;
+    using observer<T1>::notification;
+    using observer<T2>::notification;
+    using observer<T3>::notification;
+    using observer<T4>::notification;
   };
 
   //*********************************************************************
@@ -460,14 +490,16 @@ namespace etl
   template <typename T1,
             typename T2,
             typename T3>
-  class observer<T1, T2, T3>
+  class observer<T1, T2, T3> : public observer<T1>
+                             , public observer<T2>
+                             , public observer<T3>
   {
   public:
 
     virtual ~observer() {}
-    virtual void notification(T1) = 0;
-    virtual void notification(T2) = 0;
-    virtual void notification(T3) = 0;
+    using observer<T1>::notification;
+    using observer<T2>::notification;
+    using observer<T3>::notification;
   };
 
   //*********************************************************************
@@ -476,13 +508,14 @@ namespace etl
   //*********************************************************************
   template <typename T1,
             typename T2>
-  class observer<T1, T2>
+  class observer<T1, T2> : public observer<T1>
+                         , public observer<T2>
   {
   public:
 
     virtual ~observer() {}
-    virtual void notification(T1) = 0;
-    virtual void notification(T2) = 0;
+    using observer<T1>::notification;
+    using observer<T2>::notification;
   };
 
   //*********************************************************************
diff --git a/test/test_observer.cpp b/test/test_observer.cpp
index aff048f07..bf08e17b9 100644
--- a/test/test_observer.cpp
+++ b/test/test_observer.cpp
@@ -70,17 +70,10 @@ namespace
   //*****************************************************************************
   typedef etl::observer<Notification1, Notification2&, const Notification3&> ObserverType;
 
-#if !defined(ETL_OBSERVER_FORCE_CPP03_IMPLEMENTATION)
   //*****************************************************************************
   // The observer base type that does not take a notification type.
   //*****************************************************************************
   typedef etl::observer<void, int> ObserverVoidIntType;
-#else
-  //*****************************************************************************
-  // The observer base type that does not take a notification type.
-  //*****************************************************************************
-  typedef etl::observer<void> ObserverVoidType;
-#endif
 }
 
 //*****************************************************************************
@@ -122,7 +115,6 @@ class Observable2 : public etl::observable<ObserverType, 2>
 	}
 };
 
-#if !defined(ETL_OBSERVER_FORCE_CPP03_IMPLEMENTATION)
 //*****************************************************************************
 // The concrete observable 3 class.
 //*****************************************************************************
@@ -146,23 +138,6 @@ class ObservableVoidInt : public etl::observable<ObserverVoidIntType, 2>
     notify_observers(n);
   }
 };
-#else
-//*****************************************************************************
-// The concrete observable 3 class.
-//*****************************************************************************
-class ObservableVoid : public etl::observable<ObserverVoidType, 2>
-{
-public:
-
-  //*********************************
-  // Notify all of the observers.
-  //*********************************
-  void send_notifications()
-  {
-    notify_observers();
-  }
-};
-#endif
 
 //*****************************************************************************
 // The first observer type.
@@ -254,7 +229,6 @@ class Observer2 : public ObserverType
   int data3_count;
 };
 
-#if !defined(ETL_OBSERVER_FORCE_CPP03_IMPLEMENTATION)
 //*****************************************************************************
 // The third observer type.
 // If any one of the overloads is missing or a parameter declaration is incorrect
@@ -266,6 +240,7 @@ class ObserverVoidInt : public ObserverVoidIntType
 
   ObserverVoidInt()
     : data1_count(0)
+    , data2_count(0)
   {
   }
 
@@ -288,33 +263,6 @@ class ObserverVoidInt : public ObserverVoidIntType
   int data1_count;
   int data2_count;
 };
-#else
-//*****************************************************************************
-// The third observer type.
-// If any one of the overloads is missing or a parameter declaration is incorrect
-// then the class will be 'abstract' and will not compile.
-//*****************************************************************************
-class ObserverVoid : public ObserverVoidType
-{
-public:
-
-  ObserverVoid()
-    : data1_count(0)
-  {
-  }
-
-  //*******************************************
-  // Notification1
-  //*******************************************
-  void notification() override
-  {
-    ++data1_count;
-  }
-
-  int data1_count;
-  int data2_count;
-};
-#endif
 
 namespace
 {
@@ -603,7 +551,6 @@ namespace
       CHECK_EQUAL(0UL, observable.number_of_observers());
     }
 
-#if !defined(ETL_OBSERVER_FORCE_CPP03_IMPLEMENTATION)
     //*************************************************************************
     TEST(test_void_int_observable)
     {
@@ -617,24 +564,13 @@ namespace
 
       // Send the notifications.
       observable.send_notifications();
-      observable.send_notifications(1);
-    }
-#else
-    //*************************************************************************
-    TEST(test_void_observable)
-    {
-      // The observable objects.
-      ObservableVoid observable;
+      CHECK_EQUAL(1U, observer.data1_count);
+      CHECK_EQUAL(0U, observer.data2_count);
 
-      // The observer objects.
-      ObserverVoid observer;
-
-      observable.add_observer(observer);
-
-      // Send the notifications.
-      observable.send_notifications();
+      observable.send_notifications(1);
+      CHECK_EQUAL(1U, observer.data1_count);
+      CHECK_EQUAL(1U, observer.data2_count);
     }
-#endif
   }
 }