From 8f7c10f3061fbfe5dbd80b9209f5b147837edeb8 Mon Sep 17 00:00:00 2001
From: Mathew Sutcliffe <oktal3700@gmail.com>
Date: Tue, 28 Oct 2014 19:52:46 +0000
Subject: [PATCH] refs #345 Symmetric equality operators complete the original
 implementation of CValueObjectStdTuple.

---
 src/blackmisc/statusmessage.cpp | 17 -----------------
 src/blackmisc/statusmessage.h   |  6 ------
 src/blackmisc/valueobject.h     | 17 +++++++++++++++++
 3 files changed, 17 insertions(+), 23 deletions(-)

diff --git a/src/blackmisc/statusmessage.cpp b/src/blackmisc/statusmessage.cpp
index 66f2c9bdd..f5d8bf940 100644
--- a/src/blackmisc/statusmessage.cpp
+++ b/src/blackmisc/statusmessage.cpp
@@ -60,23 +60,6 @@ namespace BlackMisc
         }
     }
 
-    /*
-     * Equal?
-     */
-    bool CStatusMessage::operator ==(const CStatusMessage &other) const
-    {
-        if (this == &other) return true;
-        return TupleConverter<CStatusMessage>::toTuple(*this) == TupleConverter<CStatusMessage>::toTuple(other);
-    }
-
-    /*
-     * Unequal?
-     */
-    bool CStatusMessage::operator !=(const CStatusMessage &other) const
-    {
-        return !((*this) == other);
-    }
-
     /*
      * Conversion
      */
diff --git a/src/blackmisc/statusmessage.h b/src/blackmisc/statusmessage.h
index 5d0b77b75..183cf5014 100644
--- a/src/blackmisc/statusmessage.h
+++ b/src/blackmisc/statusmessage.h
@@ -66,12 +66,6 @@ namespace BlackMisc
         //! \sa QtMessageHandler
         void toQtLogTriple(QtMsgType *o_type, QString *o_category, QString *o_message) const;
 
-        //! Equal operator ==
-        bool operator ==(const CStatusMessage &other) const;
-
-        //! Unequal operator !=
-        bool operator !=(const CStatusMessage &other) const;
-
         //! Message category
         const CLogCategoryList &getCategories() const { return this->m_categories; }
 
diff --git a/src/blackmisc/valueobject.h b/src/blackmisc/valueobject.h
index f05f753bf..9d7b48882 100644
--- a/src/blackmisc/valueobject.h
+++ b/src/blackmisc/valueobject.h
@@ -278,6 +278,15 @@ namespace BlackMisc
      */
     template <class Derived> class CValueObjectStdTuple : public CValueObject
     {
+        friend bool operator ==(const Derived &a, const Derived &b)
+        {
+            return equals(a, b);
+        }
+
+        friend bool operator !=(const Derived &a, const Derived &b)
+        {
+            return !(a == b);
+        }
 
     public:
         //! \copydoc CValueObject::getValueHash()
@@ -362,6 +371,14 @@ namespace BlackMisc
     private:
         const Derived *derived() const { return static_cast<const Derived *>(this); }
         Derived *derived() { return static_cast<Derived *>(this); }
+
+        // Friend functions are implemented in terms of private static member functions, because
+        // friendship is not transitive: friends of CValueObjectStdTuple are not friends of TupleConverter.
+        static bool equals(const Derived &a, const Derived &b)
+        {
+            if (&a == &b) { return true; }
+            return TupleConverter<Derived>::toMetaTuple(a) == TupleConverter<Derived>::toMetaTuple(b);
+        }
     };
 
     /*!