Base: Add wrapper for PyArg_ParseTupleAndKeywords

Enable strict const-correctness for the keywords argument and address
several linter complaints related to using a C function in C++ code.

src/Base/PyWrapParseTupleAndKeywords.h

@@ -0,0 +1,70 @@
+// SPDX-License-Identifier: LGPL-2.1-or-later
+/****************************************************************************
+ *                                                                          *
+ *   Copyright (c) 2023 The FreeCAD Project Association                     *
+ *                                                                          *
+ *   This file is part of FreeCAD.                                          *
+ *                                                                          *
+ *   FreeCAD is free software: you can redistribute it and/or modify it     *
+ *   under the terms of the GNU Lesser General Public License as            *
+ *   published by the Free Software Foundation, either version 2.1 of the   *
+ *   License, or (at your option) any later version.                        *
+ *                                                                          *
+ *   FreeCAD is distributed in the hope that it will be useful, but         *
+ *   WITHOUT ANY WARRANTY; without even the implied warranty of             *
+ *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU       *
+ *   Lesser General Public License for more details.                        *
+ *                                                                          *
+ *   You should have received a copy of the GNU Lesser General Public       *
+ *   License along with FreeCAD. If not, see                                *
+ *   <https://www.gnu.org/licenses/>.                                       *
+ *                                                                          *
+ ***************************************************************************/
+
+#ifndef FREECAD_PYWRAPPARSETUPLEANDKEYWORDS_H
+#define FREECAD_PYWRAPPARSETUPLEANDKEYWORDS_H
+
+#include <Python.h>
+#include <array>
+#include <type_traits>
+
+namespace Base {
+
+    /// A thin C++ wrapper around PyArg_ParseTupleAndKeywords providing const-correctness for the keywords argument
+    /// \arg args The Python args object
+    /// \arg kw The Python kw object
+    /// \arg format The format string describing the expected arguments
+    /// \arg keywords A std::array of keywords, terminated by a nullptr (required by CPython)
+    /// \arg (variadic) Pointers to the storage locations for the parameters
+    /// \returns boolean true on success, or false on failure
+    template<size_t arraySize>
+    bool Wrapped_ParseTupleAndKeywords(PyObject *args,
+                                       PyObject *kw,
+                                       const char *format,
+                                       const std::array<const char *, arraySize> keywords,
+                                       ...)
+    {
+        // NOTE: This code is from getargs.c in the Python source code (modified to use the public interface at
+        // PyArg_VaParseTupleAndKeywords and to return a bool).
+        va_list va; // NOLINT
+
+        if ((args == nullptr || !PyTuple_Check(args)) ||
+            (kw != nullptr && !PyDict_Check(kw)) ||
+            format == nullptr ||
+            keywords.empty() || // It must at least have a single nullptr in it (TODO: compilation error instead)
+            keywords.back() != nullptr) // It must END with a nullptr
+        {
+            PyErr_BadInternalCall();
+            return false;
+        }
+
+        va_start(va, keywords);
+        // NOLINTNEXTLINE(cppcoreguidelines-pro-type-const-cast)
+        int retval = PyArg_VaParseTupleAndKeywords(args, kw, format, const_cast<char **>(keywords.data()), va);
+        va_end(va);
+        return retval != 0; // Convert to a true C++ boolean
+    }
+
+}
+
+#endif //FREECAD_PYWRAPPARSETUPLEANDKEYWORDS_H