STYLE: Use unique_ptr for data members of HDF5ImageIO

Following C++ Core Guidelines, February 15, 2024:
"Use unique_ptr or shared_ptr to avoid forgetting to delete objects created using new"
https://isocpp.github.io/CppCoreGuidelines/CppCoreGuidelines#Rh-smart

Modules/IO/HDF5/include/itkHDF5ImageIO.h

@@ -27,6 +27,7 @@
 #include "ITKIOHDF5Export.h"
 #include "itkMetaDataObjectBase.h"
 #include "itkMetaDataDictionary.h"
+#include <memory> // For unique_ptr.
 
 // itk namespace first suppresses
 // kwstyle error for the H5 namespace below
@@ -213,9 +214,9 @@ class ITKIOHDF5_EXPORT HDF5ImageIO : public StreamingImageIOBase
   void
   ResetToInitialState();
 
-  H5::H5File *  m_H5File{ nullptr };
-  H5::DataSet * m_VoxelDataSet{ nullptr };
-  bool          m_ImageInformationWritten{ false };
+  std::unique_ptr<H5::H5File>  m_H5File;
+  std::unique_ptr<H5::DataSet> m_VoxelDataSet;
+  bool                         m_ImageInformationWritten{ false };
 };
 } // end namespace itk
 

Modules/IO/HDF5/src/itkHDF5ImageIO.cxx

@@ -54,7 +54,7 @@ HDF5ImageIO::PrintSelf(std::ostream & os, Indent indent) const
 {
   Superclass::PrintSelf(os, indent);
   // just prints out the pointer value.
-  os << indent << "H5File: " << m_H5File << std::endl;
+  os << indent << "H5File: " << m_H5File.get() << std::endl;
 }
 
 //
@@ -639,8 +639,7 @@ HDF5ImageIO::ResetToInitialState()
     if (m_H5File != nullptr)
     {
       m_H5File->close();
-      delete m_H5File;
-      m_H5File = nullptr;
+      m_H5File.reset();
     }
   }
 
@@ -649,8 +648,7 @@ HDF5ImageIO::ResetToInitialState()
     if (m_VoxelDataSet != nullptr)
     {
       m_VoxelDataSet->close();
-      delete m_VoxelDataSet;
-      m_VoxelDataSet = nullptr;
+      m_VoxelDataSet.reset();
     }
   }
   // Need to reset m_ImageInformationWritten so that
@@ -666,8 +664,8 @@ HDF5ImageIO::ReadImageInformation()
   try
   {
     this->ResetToInitialState();
-    m_H5File = new H5::H5File(this->GetFileName(), H5F_ACC_RDONLY);
-    m_VoxelDataSet = new H5::DataSet();
+    m_H5File = std::make_unique<H5::H5File>(this->GetFileName(), H5F_ACC_RDONLY);
+    m_VoxelDataSet = std::make_unique<H5::DataSet>();
 
     // not sure what to do with this initially
     // eventually it will be needed if the file versions change
@@ -1034,8 +1032,8 @@ HDF5ImageIO::WriteImageInformation()
 #  error The selected version of HDF5 library does not support setting backwards compatibility at run-time.\
   Please use a different version of HDF5, e.g. the one bundled with ITK (by setting ITK_USE_SYSTEM_HDF5 to OFF).
 #endif
-    m_H5File = new H5::H5File(this->GetFileName(), H5F_ACC_TRUNC, H5::FileCreatPropList::DEFAULT, fapl);
-    m_VoxelDataSet = new H5::DataSet();
+    m_H5File = std::make_unique<H5::H5File>(this->GetFileName(), H5F_ACC_TRUNC, H5::FileCreatPropList::DEFAULT, fapl);
+    m_VoxelDataSet = std::make_unique<H5::DataSet>();
 
     this->WriteString(ItkVersion, Version::GetITKVersion());