Base: implement a lightweight smart pointer for PyObject like Py::Object to reduce includes of Python.h in header files

src/Base/SmartPtrPy.h

@@ -0,0 +1,86 @@
+/***************************************************************************
+ *   Copyright (c) 2020 Werner Mayer <wmayer[at]users.sourceforge.net>     *
+ *                                                                         *
+ *   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                                *
+ *                                                                         *
+ ***************************************************************************/
+
+
+#ifndef PY_SMARTPTRPY_H
+#define PY_SMARTPTRPY_H
+
+// forward declarations
+typedef struct _object PyObject;
+
+namespace Py {
+class Object;
+
+/**
+ * \brief This is a stripped-down version of Py::Object.
+ * The purpose of this class is to avoid to include any other header file
+ * and therefore the PyObject is forward declared and the implementation
+ * is separated from the class declaration.
+ *
+ * \author Werner Mayer
+ */
+class BaseExport SmartPtr
+{
+private:
+    PyObject *p;
+
+protected:
+    void set(PyObject *pyob, bool owned = false);
+    void release();
+
+public:
+    SmartPtr();
+
+    // Constructor acquires new ownership of pointer unless explicitly told not to.
+    explicit SmartPtr(PyObject *pyob, bool owned = false);
+
+    // Copy constructor acquires new ownership of pointer
+    SmartPtr(const SmartPtr &ob);
+
+    // Assignment acquires new ownership of pointer
+    SmartPtr &operator=( const Object &SmartPtr );
+
+    SmartPtr &operator=(PyObject *rhsp);
+
+    // Destructor
+    virtual ~SmartPtr();
+
+    // Loaning the pointer to others, retain ownership
+    PyObject *operator*() const;
+
+    // Would like to call this pointer() but messes up STL in SeqBase<T>
+    PyObject *ptr() const;
+    //
+    // Queries
+    //
+
+    bool is(PyObject *pother) const;
+    bool is(const SmartPtr &other) const;
+
+    bool isNull() const;
+};
+
+BaseExport PyObject* new_reference_to(const SmartPtr&);
+
+}
+
+#endif // PY_SMARTPTRPY_H