From a05b85135cc5f21f4840c8b7b597b8f4758203bf Mon Sep 17 00:00:00 2001
From: Mathew Sutcliffe <oktal3700@gmail.com>
Date: Tue, 30 Apr 2013 00:09:32 +0100
Subject: [PATCH] replaced "clone" with "derived" in CRTP (more usual, more
 flexible, more clear in its intent, and avoids copying the object twice on
 compilers that don't optimise return by value)

---
 src/blackmisc/mathmatrixbase.cpp     |  2 +-
 src/blackmisc/mathmatrixbase.h       | 31 ++++++++++++++++++----------
 src/blackmisc/mathvector3dbase.h     | 28 ++++++++++++++++---------
 src/blackmisc/pqphysicalquantity.cpp |  8 +++----
 src/blackmisc/pqphysicalquantity.h   | 15 +++++++++++---
 5 files changed, 55 insertions(+), 29 deletions(-)

diff --git a/src/blackmisc/mathmatrixbase.cpp b/src/blackmisc/mathmatrixbase.cpp
index 9d28779ca..99a1dadd3 100644
--- a/src/blackmisc/mathmatrixbase.cpp
+++ b/src/blackmisc/mathmatrixbase.cpp
@@ -97,7 +97,7 @@ template<class ImplMatrix, int Rows, int Columns> ImplMatrix &CMatrixBase<ImplMa
             this->m_matrix(r, c) = CMath::roundEpsilon(this->m_matrix(r, c), 1E-10);
         }
     }
-    return static_cast<ImplMatrix &>(*this);
+    return *derived();
 }
 
 /*
diff --git a/src/blackmisc/mathmatrixbase.h b/src/blackmisc/mathmatrixbase.h
index 2841a3385..8b3b6152b 100644
--- a/src/blackmisc/mathmatrixbase.h
+++ b/src/blackmisc/mathmatrixbase.h
@@ -32,12 +32,21 @@ protected:
     QString stringForConverter() const;
 
     /*!
-     * \brief Clone as conrete implementation
+     * \brief Easy access to derived class (CRTP template parameter)
      * \return
      */
-    ImplMatrix clone() const
+    ImplMatrix const* derived() const
     {
-        return static_cast<ImplMatrix const &>(*this);
+        return static_cast<ImplMatrix const *>(this);
+    }
+
+    /*!
+     * \brief Easy access to derived class (CRTP template parameter)
+     * \return
+     */
+    ImplMatrix* derived()
+    {
+        return static_cast<ImplMatrix *>(this);
     }
 
 public:
@@ -118,7 +127,7 @@ public:
      */
     ImplMatrix operator *(double factor) const
     {
-        ImplMatrix m = this->clone();
+        ImplMatrix m = *derived();
         m *= factor;
         return m;
     }
@@ -159,7 +168,7 @@ public:
      */
     ImplMatrix operator /(double factor) const
     {
-        ImplMatrix m = this->clone();
+        ImplMatrix m = *derived();
         m /= factor;
         return m;
     }
@@ -182,7 +191,7 @@ public:
      */
     ImplMatrix operator +(const ImplMatrix &otherMatrix) const
     {
-        ImplMatrix m = this->clone();
+        ImplMatrix m = *derived();
         m += otherMatrix;
         return m;
     }
@@ -205,7 +214,7 @@ public:
      */
     ImplMatrix operator -(const ImplMatrix &otherMatrix) const
     {
-        ImplMatrix m = this->clone();
+        ImplMatrix m = *derived();
         m -= otherMatrix;
         return m;
     }
@@ -225,8 +234,8 @@ public:
      */
     bool isIdentityEpsilon() const
     {
-        ImplMatrix m = this->clone().round();
-        return m.isIdentity();
+        ImplMatrix m = *derived();
+        return m.round().isIdentity();
     }
 
     /*!
@@ -260,8 +269,8 @@ public:
      */
     bool isZeroEpsilon() const
     {
-        ImplMatrix m = this->clone().round();
-        return m.isZero();
+        ImplMatrix m = *derived();
+        return m.round().isZero();
     }
 
     /*!
diff --git a/src/blackmisc/mathvector3dbase.h b/src/blackmisc/mathvector3dbase.h
index 8183c325e..1fe7d6133 100644
--- a/src/blackmisc/mathvector3dbase.h
+++ b/src/blackmisc/mathvector3dbase.h
@@ -62,14 +62,22 @@ protected:
     virtual QString stringForConverter() const;
 
     /*!
-     * \brief Clone as concrete implementation
+     * \brief Easy access to derived class (CRTP template parameter)
      * \return
      */
-    ImplVector clone() const
+    ImplVector const* derived() const
     {
-        return static_cast<ImplVector const &>(*this);
+        return static_cast<ImplVector const *>(this);
     }
 
+    /*!
+     * \brief Easy access to derived class (CRTP template parameter)
+     * \return
+     */
+    ImplVector* derived()
+    {
+        return static_cast<ImplVector *>(this);
+    }
 
 public:
 
@@ -198,7 +206,7 @@ public:
      */
     ImplVector operator +(const ImplVector &otherVector) const
     {
-        ImplVector v = this->clone();
+        ImplVector v = *derived();
         v += otherVector;
         return v;
     }
@@ -223,7 +231,7 @@ public:
      */
     ImplVector operator -(const ImplVector &otherVector) const
     {
-        ImplVector v = this->clone();
+        ImplVector v = *derived();
         v -= otherVector;
         return v;
     }
@@ -248,7 +256,7 @@ public:
      */
     ImplVector operator *(const ImplVector &otherVector) const
     {
-        ImplVector v = this->clone();
+        ImplVector v = *derived();
         v *= otherVector;
         return v;
     }
@@ -273,7 +281,7 @@ public:
      */
     ImplVector operator *(double factor) const
     {
-        ImplVector v = this->clone();
+        ImplVector v = *derived();
         v *= factor;
         return v;
     }
@@ -309,7 +317,7 @@ public:
      */
     ImplVector operator /(double divisor) const
     {
-        ImplVector v = this->clone();
+        ImplVector v = *derived();
         v /= divisor;
         return v;
     }
@@ -334,7 +342,7 @@ public:
      */
     ImplVector operator /(const ImplVector &otherVector) const
     {
-        ImplVector v = this->clone();
+        ImplVector v = *derived();
         v /= otherVector;
         return v;
     }
@@ -413,7 +421,7 @@ public:
         this->m_i = BlackMisc::Math::CMath::roundEpsilon(this->m_i, epsilon);
         this->m_j = BlackMisc::Math::CMath::roundEpsilon(this->m_j, epsilon);
         this->m_k = BlackMisc::Math::CMath::roundEpsilon(this->m_k, epsilon);
-        return static_cast<ImplVector &>(*this);
+        return *derived();
     }
 };
 
diff --git a/src/blackmisc/pqphysicalquantity.cpp b/src/blackmisc/pqphysicalquantity.cpp
index ff65846f8..937d782ef 100644
--- a/src/blackmisc/pqphysicalquantity.cpp
+++ b/src/blackmisc/pqphysicalquantity.cpp
@@ -190,7 +190,7 @@ template <class MU, class PQ> CPhysicalQuantity<MU, PQ> &CPhysicalQuantity<MU, P
  */
 template <class MU, class PQ> PQ CPhysicalQuantity<MU, PQ>::operator -(const PQ &otherQuantity) const
 {
-    PQ minus = this->clone();
+    PQ minus = *derived();
     minus -= otherQuantity;
     return minus;
 }
@@ -209,7 +209,7 @@ template <class MU, class PQ> CPhysicalQuantity<MU, PQ> &CPhysicalQuantity<MU, P
  */
 template <class MU, class PQ> PQ CPhysicalQuantity<MU, PQ>::operator *(double multiply) const
 {
-    PQ times = this->clone();
+    PQ times = *derived();
     times *= multiply;
     return times;
 }
@@ -228,7 +228,7 @@ template <class MU, class PQ> CPhysicalQuantity<MU, PQ> &CPhysicalQuantity<MU, P
  */
 template <class MU, class PQ> PQ CPhysicalQuantity<MU, PQ>::operator /(double divide) const
 {
-    PQ div = this->clone();
+    PQ div = *derived();
     div /= divide;
     return div;
 }
@@ -281,7 +281,7 @@ template <class MU, class PQ> PQ &CPhysicalQuantity<MU, PQ>::switchUnit(const MU
         this->m_unit = newUnit;
         this->setUnitValue(cf);
     }
-    return static_cast<PQ &>(*this);
+    return *derived();
 }
 
 /*
diff --git a/src/blackmisc/pqphysicalquantity.h b/src/blackmisc/pqphysicalquantity.h
index 2314e0e48..053fcf829 100644
--- a/src/blackmisc/pqphysicalquantity.h
+++ b/src/blackmisc/pqphysicalquantity.h
@@ -60,12 +60,21 @@ protected:
     }
 
     /*!
-     * \brief Polymorphic clone as concrete class
+     * \brief Easy access to derived class (CRTP template parameter)
      * \return
      */
-    PQ clone() const
+    PQ const* derived() const
     {
-        return static_cast<PQ const &>(*this);
+        return static_cast<PQ const *>(this);
+    }
+
+    /*!
+     * \brief Easy access to derived class (CRTP template parameter)
+     * \return
+     */
+    PQ* derived()
+    {
+        return static_cast<PQ *>(this);
     }
 
     /*!