Ref T275, defined the pairs we are using

src/blackmisc/pair.h

@@ -0,0 +1,43 @@
+/* Copyright (C) 2018
+ * Swift Project Community / Contributors
+ *
+ * This file is part of Swift Project. It is subject to the license terms in the LICENSE file found in the top-level
+ * directory of this distribution and at http://www.swift-project.org/license.html. No part of swift project,
+ * including this file, may be copied, modified, propagated, or distributed except according to the terms
+ * contained in the LICENSE file.
+ */
+
+//! \file
+
+#ifndef BLACKMISC_PAIR_H
+#define BLACKMISC_PAIR_H
+
+#include "blackmisc/aviation/altitude.h"
+#include "blackmisc/pq/angle.h"
+#include "blackmisc/pq/length.h"
+#include "blackmisc/pq/speed.h"
+#include "blackmisc/variant.h"
+
+#include <QPair>
+#include <QDBusMetaType>
+
+namespace BlackMisc
+{
+    namespace PhysicalQuantities
+    {
+        using CAnglePair = QPair<CAngle, CAngle>;     //!< Pair of angle
+        using CLengthPair = QPair<CLength, CLength>;  //!< Pair of length
+        using CSpeedPair = QPair<CSpeed, CSpeed>;     //!< Pair of speed
+    }
+    namespace Aviation
+    {
+        using CAltitudePair = QPair<CAltitude, CAltitude>; //!< Pair of altitude
+    }
+} // namespace
+
+Q_DECLARE_METATYPE(BlackMisc::PhysicalQuantities::CAnglePair)
+Q_DECLARE_METATYPE(BlackMisc::PhysicalQuantities::CLengthPair)
+Q_DECLARE_METATYPE(BlackMisc::PhysicalQuantities::CSpeedPair)
+Q_DECLARE_METATYPE(BlackMisc::Aviation::CAltitudePair)
+
+#endif // guard