From: Luca Heltai <luca.heltai@sissa.it>
Date: Tue, 20 Dec 2022 17:54:13 +0000 (+0100)
Subject: Apply suggestions from code review
X-Git-Tag: v9.5.0-rc1~715^2
X-Git-Url: https://gitweb.dealii.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=8e50cb3342c6c2682e903bcdb40f6a833e9294a6;p=dealii.git

Apply suggestions from code review

Co-authored-by: David Wells <drwells@email.unc.edu>
---

diff --git a/include/deal.II/lac/petsc_matrix_base.h b/include/deal.II/lac/petsc_matrix_base.h
index dea9e730cb..2fd3d37f0c 100644
--- a/include/deal.II/lac/petsc_matrix_base.h
+++ b/include/deal.II/lac/petsc_matrix_base.h
@@ -305,8 +305,22 @@ namespace PETScWrappers
     MatrixBase();
 
     /**
-     * Initialize a Matrix from a PETSc Mat object. Note that we do not copy
-     * the matrix.
+     * Initialize a Matrix from a PETSc Mat object. Note that we do not copy the
+     * matrix. Any PETSc object (including the Mat type) is in fact a reference
+     * counted pointer.
+     *
+     * A reference counted pointer is a type of pointer that maintains a
+     * reference count for the object it points to. The reference count is
+     * incremented each time a new reference to the object is created, and
+     * decremented each time a reference is destroyed. When the reference count
+     * reaches zero, the object is automatically deleted, freeing up the memory
+     * it was using.
+     *
+     * In the context of PETSc, reference counted pointers are used to manage
+     * the memory of objects such as vectors, matrices, and solvers. By using
+     * reference counted pointers, PETSc ensures that memory is automatically
+     * released when it is no longer needed, without the need for explicit
+     * memory management.
      */
     explicit MatrixBase(const Mat &);
 
diff --git a/source/lac/petsc_matrix_base.cc b/source/lac/petsc_matrix_base.cc
index 185fbf9997..72e0217b97 100644
--- a/source/lac/petsc_matrix_base.cc
+++ b/source/lac/petsc_matrix_base.cc
@@ -86,8 +86,7 @@ namespace PETScWrappers
   {
     const PetscErrorCode ierr =
       PetscObjectReference(reinterpret_cast<PetscObject>(matrix));
-    AssertNothrow(ierr == 0, ExcPETScError(ierr));
-    (void)ierr;
+    AssertThrow(ierr == 0, ExcPETScError(ierr));
   }