Part: GeometryDefaultExtensions template

========================================

Generalisation of code for a default geometry extension in the form of a template.

Default geometry extensions provide a standard interface for an extension having a single stored value (e.g. one int or one string).

Python implementation must be provided separatedly.

src/Mod/Part/App/GeometryDefaultExtension.cpp

@@ -0,0 +1,113 @@
+/***************************************************************************
+ *   Copyright (c) 2019 Abdullah Tahiri <abdullah.tahiri.yo@gmail.com>     *
+ *                                                                         *
+ *   This file is part of the FreeCAD CAx development system.              *
+ *                                                                         *
+ *   This library is free software; you can redistribute it and/or         *
+ *   modify it under the terms of the GNU Library General Public           *
+ *   License as published by the Free Software Foundation; either          *
+ *   version 2 of the License, or (at your option) any later version.      *
+ *                                                                         *
+ *   This library  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 Library General Public License for more details.                  *
+ *                                                                         *
+ *   You should have received a copy of the GNU Library General Public     *
+ *   License along with this library; see the file COPYING.LIB. If not,    *
+ *   write to the Free Software Foundation, Inc., 59 Temple Place,         *
+ *   Suite 330, Boston, MA  02111-1307, USA                                *
+ *                                                                         *
+ ***************************************************************************/
+
+
+#include "PreCompiled.h"
+
+#include <Base/Writer.h>
+#include <Base/Reader.h>
+#include <Base/Tools.h>
+#include <Base/Exception.h>
+
+#include "GeometryDefaultExtension.h"
+
+#include "GeometryStringExtensionPy.h"
+#include "GeometryIntExtensionPy.h"
+
+using namespace Part;
+
+//---------- Geometry Extension
+template <typename T>
+GeometryDefaultExtension<T>::GeometryDefaultExtension(const T& obj):value(obj)
+{
+
+}
+
+// Persistence implementer
+template <typename T>
+unsigned int GeometryDefaultExtension<T>::getMemSize (void) const
+{
+    return 1;
+}
+
+template <typename T>
+void GeometryDefaultExtension<T>::Save(Base::Writer &writer) const
+{
+
+    writer.Stream() << writer.ind() << "<GeoExtension type=\"" << this->getTypeId().getName()
+    << "\" value=\"" << value << "\"/>" << std::endl;
+}
+
+template <typename T>
+void GeometryDefaultExtension<T>::Restore(Base::XMLReader &reader)
+{
+    value = reader.getAttribute("value");
+}
+
+template <typename T>
+std::unique_ptr<Part::GeometryExtension> GeometryDefaultExtension<T>::copy(void) const
+{
+    std::unique_ptr<GeometryDefaultExtension<T>> cpy = std::make_unique<GeometryDefaultExtension<T>>();
+
+    cpy->value = this->value;
+
+    return cpy;
+    // Don't std::move(cpy); RVO optimization Item 25, if the compiler fails to elide, would have to move it anyway
+    // move constructor is executed if available (it is). Unique_ptr does not have copy constructor.
+}
+
+template <typename T>
+PyObject * GeometryDefaultExtension<T>::getPyObject(void)
+{
+    THROWM(Base::NotImplementedError,"Python object not implemented for default geometry extension template type. Template Specialisation missing."); // use template specialisation to provide the actual object
+}
+
+// ----------------------------- Template specialisations----------------------------------------------------
+
+//typedef Part::GeometryDefaultExtension<int> GeometryIntExtension;
+//typedef Part::GeometryStringExtension<std::string> GeometryStringExtension;
+
+// ---------- GeometryIntExtension ----------
+TYPESYSTEM_SOURCE_TEMPLATE_T(Part::GeometryIntExtension,Part::GeometryExtension)
+
+template <>
+PyObject * GeometryDefaultExtension<int>::getPyObject(void)
+{
+    return new GeometryIntExtensionPy(new GeometryIntExtension(this->value));
+}
+
+template <>
+void GeometryDefaultExtension<int>::Restore(Base::XMLReader &reader)
+{
+    value = reader.getAttributeAsInteger("value");
+}
+
+// ---------- GeometryStringExtension ----------
+TYPESYSTEM_SOURCE_TEMPLATE_T(Part::GeometryStringExtension,Part::GeometryExtension)
+
+template <>
+PyObject * GeometryDefaultExtension<std::string>::getPyObject(void)
+{
+    return new GeometryStringExtensionPy(new GeometryStringExtension(this->value));
+}
+
+