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LSST Data Management Base Package
PyObjectPtr.h
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1 /*
2  * This file is part of log.
3  *
4  * Developed for the LSST Data Management System.
5  * This product includes software developed by the LSST Project
6  * (https://www.lsst.org).
7  * See the COPYRIGHT file at the top-level directory of this distribution
8  * for details of code ownership.
9  *
10  * This program is free software: you can redistribute it and/or modify
11  * it under the terms of the GNU General Public License as published by
12  * the Free Software Foundation, either version 3 of the License, or
13  * (at your option) any later version.
14  *
15  * This program is distributed in the hope that it will be useful,
16  * but WITHOUT ANY WARRANTY; without even the implied warranty of
17  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
18  * GNU General Public License for more details.
19  *
20  * You should have received a copy of the GNU General Public License
21  * along with this program. If not, see <https://www.gnu.org/licenses/>.
22  */
23 
24 #ifndef LSST_LOG_PYOBJECTPTR_H
25 #define LSST_LOG_PYOBJECTPTR_H
26 
27 // Python header has to be first to avoid compilation warnings
28 #include "Python.h"
29 
30 #include <cstddef>
31 
32 namespace lsst::log::detail {
33 
37 class PyObjectPtr {
38 public:
39 
43  static PyObjectPtr from_borrowed(PyObject* object) {
44  Py_XINCREF(object);
45  return PyObjectPtr(object);
46  }
47 
51  explicit PyObjectPtr(PyObject* object = nullptr) : m_object(object) {}
52 
53  // copy constructor, increments ref. counter
54  PyObjectPtr(PyObjectPtr const& other) : m_object(other.m_object) {
55  Py_XINCREF(m_object);
56  }
57 
58  // move constructor, steals reference
59  PyObjectPtr(PyObjectPtr&& other) : m_object(other.m_object) {
60  other.m_object = nullptr;
61  }
62 
63  // Decrement ref. counter
64  ~PyObjectPtr() { Py_CLEAR(m_object); }
65 
67  Py_CLEAR(m_object);
68  m_object = other.m_object;
69  Py_XINCREF(m_object);
70  return *this;
71  }
72 
74  Py_CLEAR(m_object);
75  m_object = other.m_object;
76  other.m_object = nullptr;
77  return *this;
78  }
79 
80  PyObjectPtr& operator=(PyObject* object) {
81  Py_CLEAR(m_object);
82  m_object = object;
83  Py_XINCREF(m_object);
84  return *this;
85  }
86 
87  // can be converted to regular pointer
88  operator PyObject*() const { return m_object; }
89 
90  // release ownership
91  PyObject* release() {
92  auto object = m_object;
93  m_object = nullptr;
94  return object;
95  }
96 
97  // This returns a reference so you can take a pointer of a pointer, needed
98  // for some API methods.
99  PyObject*& get() { return m_object; }
100 
101  // compare to nullptr
102  bool operator==(std::nullptr_t) const { return m_object == nullptr; }
103  bool operator!=(std::nullptr_t) const { return m_object != nullptr; }
104 
105 private:
106 
107  PyObject* m_object = nullptr;
108 };
109 
110 } // namespace lsst::log::detail
111 
112 #endif // LSST_LOG_PYOBJECTPTR_H
Smart pointer class for PyObject instances.
Definition: PyObjectPtr.h:37
PyObjectPtr & operator=(PyObjectPtr &&other)
Definition: PyObjectPtr.h:73
bool operator!=(std::nullptr_t) const
Definition: PyObjectPtr.h:103
static PyObjectPtr from_borrowed(PyObject *object)
Wraps a "borrowed" object reference, reference counter is incremented.
Definition: PyObjectPtr.h:43
PyObjectPtr & operator=(PyObject *object)
Definition: PyObjectPtr.h:80
bool operator==(std::nullptr_t) const
Definition: PyObjectPtr.h:102
PyObjectPtr(PyObjectPtr const &other)
Definition: PyObjectPtr.h:54
PyObjectPtr(PyObject *object=nullptr)
Construct a pointer from a regular "new" object reference.
Definition: PyObjectPtr.h:51
PyObjectPtr(PyObjectPtr &&other)
Definition: PyObjectPtr.h:59
PyObjectPtr & operator=(PyObjectPtr const &other)
Definition: PyObjectPtr.h:66