ENH: Add C++17 [[nodiscard]] to Image "Transform" member functions

It would usually be a mistake when a user would unintentionally ignore the return value of those member functions. Specifically, the overloads of `TransformPhysicalPointToIndex` and `TransformPhysicalPointToContinuousIndex` that have two parameters both return a `bool` value. If this return value can be ignored, it is preferable (for performance reasons) to call the corresponding overload that has one parameter instead. The compiler may now produce a warning when the return value of any of those member functions is unintentionally ignored.
InsightSoftwareConsortium · Apr 5, 2023 · 63d4354 · 63d4354
1 parent 1d03697
commit 63d4354
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Showing 3 changed files with 22 additions and 22 deletions.
diff --git a/Modules/Core/Common/include/itkImageBase.h b/Modules/Core/Common/include/itkImageBase.h
@@ -439,7 +439,7 @@ class ITK_TEMPLATE_EXPORT ImageBase : public DataObject
      \endcode
    * \sa Transform */
   template <typename TCoordRep>
-  IndexType
+  [[nodiscard]] IndexType
   TransformPhysicalPointToIndex(const Point<TCoordRep, VImageDimension> & point) const
   {
     IndexType index;
@@ -465,7 +465,7 @@ class ITK_TEMPLATE_EXPORT ImageBase : public DataObject
    *
    * \sa Transform */
   template <typename TCoordRep>
-  bool
+  [[nodiscard]] bool
   TransformPhysicalPointToIndex(const Point<TCoordRep, VImageDimension> & point, IndexType & index) const
   {
     index = TransformPhysicalPointToIndex(point);
@@ -491,7 +491,7 @@ class ITK_TEMPLATE_EXPORT ImageBase : public DataObject
      \endcode
    * \sa Transform */
   template <typename TIndexRep, typename TCoordRep>
-  ContinuousIndex<TIndexRep, VImageDimension>
+  [[nodiscard]] ContinuousIndex<TIndexRep, VImageDimension>
   TransformPhysicalPointToContinuousIndex(const Point<TCoordRep, VImageDimension> & point) const
   {
     ContinuousIndex<TIndexRep, VImageDimension> index;
@@ -518,7 +518,7 @@ class ITK_TEMPLATE_EXPORT ImageBase : public DataObject
    *
    * \sa Transform */
   template <typename TCoordRep, typename TIndexRep>
-  bool
+  [[nodiscard]] bool
   TransformPhysicalPointToContinuousIndex(const Point<TCoordRep, VImageDimension> &     point,
                                           ContinuousIndex<TIndexRep, VImageDimension> & index) const
   {
@@ -554,7 +554,7 @@ class ITK_TEMPLATE_EXPORT ImageBase : public DataObject
    * from a continuous index (in the index space)
    * \sa Transform */
   template <typename TCoordRep, typename TIndexRep>
-  Point<TCoordRep, VImageDimension>
+  [[nodiscard]] Point<TCoordRep, VImageDimension>
   TransformContinuousIndexToPhysicalPoint(const ContinuousIndex<TIndexRep, VImageDimension> & index) const
   {
     Point<TCoordRep, VImageDimension> point;
@@ -587,7 +587,7 @@ class ITK_TEMPLATE_EXPORT ImageBase : public DataObject
    *
    * \sa Transform */
   template <typename TCoordRep>
-  Point<TCoordRep, VImageDimension>
+  [[nodiscard]] Point<TCoordRep, VImageDimension>
   TransformIndexToPhysicalPoint(const IndexType & index) const
   {
     Point<TCoordRep, VImageDimension> point;
@@ -637,7 +637,7 @@ class ITK_TEMPLATE_EXPORT ImageBase : public DataObject
    * \sa Image
    */
   template <typename TVector>
-  TVector
+  [[nodiscard]] TVector
   TransformLocalVectorToPhysicalVector(const TVector & inputGradient) const
   {
     TVector outputGradient;
@@ -686,7 +686,7 @@ class ITK_TEMPLATE_EXPORT ImageBase : public DataObject
    *
    */
   template <typename TVector>
-  TVector
+  [[nodiscard]] TVector
   TransformPhysicalVectorToLocalVector(const TVector & inputGradient) const
   {
     TVector outputGradient;

diff --git a/Modules/Core/Common/include/itkPhasedArray3DSpecialCoordinatesImage.h b/Modules/Core/Common/include/itkPhasedArray3DSpecialCoordinatesImage.h
@@ -183,7 +183,7 @@ class ITK_TEMPLATE_EXPORT PhasedArray3DSpecialCoordinatesImage : public SpecialC
 
   /** Returns the continuous index from a physical point */
   template <typename TIndexRep, typename TCoordRep>
-  ContinuousIndex<TIndexRep, 3>
+  [[nodiscard]] ContinuousIndex<TIndexRep, 3>
   TransformPhysicalPointToContinuousIndex(const Point<TCoordRep, 3> & point) const
   {
     const RegionType region = this->GetLargestPossibleRegion();
@@ -217,7 +217,7 @@ class ITK_TEMPLATE_EXPORT PhasedArray3DSpecialCoordinatesImage : public SpecialC
    *
    * \sa Transform */
   template <typename TCoordRep, typename TIndexRep>
-  bool
+  [[nodiscard]] bool
   TransformPhysicalPointToContinuousIndex(const Point<TCoordRep, 3> &     point,
                                           ContinuousIndex<TIndexRep, 3> & index) const
   {
@@ -233,7 +233,7 @@ class ITK_TEMPLATE_EXPORT PhasedArray3DSpecialCoordinatesImage : public SpecialC
    * Floating point index results are truncated to integers.
    */
   template <typename TCoordRep>
-  IndexType
+  [[nodiscard]] IndexType
   TransformPhysicalPointToIndex(const Point<TCoordRep, 3> & point) const
   {
     const RegionType region = this->GetLargestPossibleRegion();
@@ -267,7 +267,7 @@ class ITK_TEMPLATE_EXPORT PhasedArray3DSpecialCoordinatesImage : public SpecialC
    *
    * \sa Transform */
   template <typename TCoordRep>
-  bool
+  [[nodiscard]] bool
   TransformPhysicalPointToIndex(const Point<TCoordRep, 3> & point, IndexType & index) const
   {
     index = this->TransformPhysicalPointToIndex(point);
@@ -308,7 +308,7 @@ class ITK_TEMPLATE_EXPORT PhasedArray3DSpecialCoordinatesImage : public SpecialC
 
   /** Returns a physical point from a continuous index. */
   template <typename TCoordRep, typename TIndexRep>
-  Point<TCoordRep, 3>
+  [[nodiscard]] Point<TCoordRep, 3>
   TransformContinuousIndexToPhysicalPoint(const ContinuousIndex<TIndexRep, 3> & index) const
   {
     Point<TCoordRep, 3> point;
@@ -346,7 +346,7 @@ class ITK_TEMPLATE_EXPORT PhasedArray3DSpecialCoordinatesImage : public SpecialC
 
   /** Returns a physical point from a discrete index. */
   template <typename TCoordRep>
-  Point<TCoordRep, 3>
+  [[nodiscard]] Point<TCoordRep, 3>
   TransformIndexToPhysicalPoint(const IndexType & index) const
   {
     Point<TCoordRep, 3> point;

diff --git a/Modules/Core/ImageAdaptors/include/itkImageAdaptor.h b/Modules/Core/ImageAdaptors/include/itkImageAdaptor.h
@@ -383,7 +383,7 @@ class ITK_TEMPLATE_EXPORT ImageAdaptor : public ImageBase<TImage::ImageDimension
 
   /** Returns the continuous index from a physical point. */
   template <typename TIndexRep, typename TCoordRep>
-  ContinuousIndex<TIndexRep, TImage::ImageDimension>
+  [[nodiscard]] ContinuousIndex<TIndexRep, TImage::ImageDimension>
   TransformPhysicalPointToContinuousIndex(const Point<TCoordRep, TImage::ImageDimension> & point) const
   {
     return m_Image->template TransformPhysicalPointToContinuousIndex<TIndexRep>(point);
@@ -398,7 +398,7 @@ class ITK_TEMPLATE_EXPORT ImageAdaptor : public ImageBase<TImage::ImageDimension
    *
    * \sa Transform */
   template <typename TCoordRep>
-  bool
+  [[nodiscard]] bool
   TransformPhysicalPointToContinuousIndex(const Point<TCoordRep, Self::ImageDimension> &     point,
                                           ContinuousIndex<TCoordRep, Self::ImageDimension> & index) const
   {
@@ -407,7 +407,7 @@ class ITK_TEMPLATE_EXPORT ImageAdaptor : public ImageBase<TImage::ImageDimension
 
   /** Returns the index (discrete) of a voxel from a physical point. */
   template <typename TCoordRep>
-  IndexType
+  [[nodiscard]] IndexType
   TransformPhysicalPointToIndex(const Point<TCoordRep, Self::ImageDimension> & point) const
   {
     return m_Image->TransformPhysicalPointToIndex(point);
@@ -422,7 +422,7 @@ class ITK_TEMPLATE_EXPORT ImageAdaptor : public ImageBase<TImage::ImageDimension
    *
    * \sa Transform */
   template <typename TCoordRep>
-  bool
+  [[nodiscard]] bool
   TransformPhysicalPointToIndex(const Point<TCoordRep, Self::ImageDimension> & point, IndexType & index) const
   {
     return m_Image->TransformPhysicalPointToIndex(point, index);
@@ -442,7 +442,7 @@ class ITK_TEMPLATE_EXPORT ImageAdaptor : public ImageBase<TImage::ImageDimension
 
   /** Returns a physical point from a continuous index (in the index space) */
   template <typename TCoordRep, typename TIndexRep>
-  Point<TCoordRep, TImage::ImageDimension>
+  [[nodiscard]] Point<TCoordRep, TImage::ImageDimension>
   TransformContinuousIndexToPhysicalPoint(const ContinuousIndex<TIndexRep, Self::ImageDimension> & index) const
   {
     return m_Image->template TransformContinuousIndexToPhysicalPoint<TIndexRep>(index);
@@ -462,7 +462,7 @@ class ITK_TEMPLATE_EXPORT ImageAdaptor : public ImageBase<TImage::ImageDimension
 
   /** Returns a physical point from a discrete index (in the index space) */
   template <typename TCoordRep>
-  Point<TCoordRep, Self::ImageDimension>
+  [[nodiscard]] Point<TCoordRep, Self::ImageDimension>
   TransformIndexToPhysicalPoint(const IndexType & index) const
   {
     return m_Image->template TransformIndexToPhysicalPoint<TCoordRep>(index);
@@ -477,7 +477,7 @@ class ITK_TEMPLATE_EXPORT ImageAdaptor : public ImageBase<TImage::ImageDimension
   }
 
   template <typename TVector>
-  TVector
+  [[nodiscard]] TVector
   TransformLocalVectorToPhysicalVector(const TVector & inputGradient) const
   {
     TVector outputGradient;
@@ -494,7 +494,7 @@ class ITK_TEMPLATE_EXPORT ImageAdaptor : public ImageBase<TImage::ImageDimension
   }
 
   template <typename TVector>
-  TVector
+  [[nodiscard]] TVector
   TransformPhysicalVectorToLocalVector(const TVector & inputGradient) const
   {
     TVector outputGradient;