changelog.rst revision 12391
1.. _changelog:
2
3Changelog
4#########
5
6Starting with version 1.8.0, pybind11 releases use a `semantic versioning
7<http://semver.org>`_ policy.
8
9v2.3.0 (Not yet released)
10-----------------------------------------------------
11
12* TBD
13
14v2.2.1 (September 14, 2017)
15-----------------------------------------------------
16
17* Added ``py::module::reload()`` member function for reloading a module.
18  `#1040 <https://github.com/pybind/pybind11/pull/1040>`_.
19
20* Fixed a reference leak in the number converter.
21  `#1078 <https://github.com/pybind/pybind11/pull/1078>`_.
22
23* Fixed compilation with Clang on host GCC < 5 (old libstdc++ which isn't fully
24  C++11 compliant). `#1062 <https://github.com/pybind/pybind11/pull/1062>`_.
25
26* Fixed a regression where the automatic ``std::vector<bool>`` caster would
27  fail to compile. The same fix also applies to any container which returns
28  element proxies instead of references.
29  `#1053 <https://github.com/pybind/pybind11/pull/1053>`_.
30
31* Fixed a regression where the ``py::keep_alive`` policy could not be applied
32  to constructors. `#1065 <https://github.com/pybind/pybind11/pull/1065>`_.
33
34* Fixed a nullptr dereference when loading a ``py::module_local`` type
35  that's only registered in an external module.
36  `#1058 <https://github.com/pybind/pybind11/pull/1058>`_.
37
38* Fixed implicit conversion of accessors to types derived from ``py::object``.
39  `#1076 <https://github.com/pybind/pybind11/pull/1076>`_.
40
41* The ``name`` in ``PYBIND11_MODULE(name, variable)`` can now be a macro.
42  `#1082 <https://github.com/pybind/pybind11/pull/1082>`_.
43
44* Relaxed overly strict ``py::pickle()`` check for matching get and set types.
45  `#1064 <https://github.com/pybind/pybind11/pull/1064>`_.
46
47* Conversion errors now try to be more informative when it's likely that
48  a missing header is the cause (e.g. forgetting ``<pybind11/stl.h>``).
49  `#1077 <https://github.com/pybind/pybind11/pull/1077>`_.
50
51v2.2.0 (August 31, 2017)
52-----------------------------------------------------
53
54* Support for embedding the Python interpreter. See the
55  :doc:`documentation page </advanced/embedding>` for a
56  full overview of the new features.
57  `#774 <https://github.com/pybind/pybind11/pull/774>`_,
58  `#889 <https://github.com/pybind/pybind11/pull/889>`_,
59  `#892 <https://github.com/pybind/pybind11/pull/892>`_,
60  `#920 <https://github.com/pybind/pybind11/pull/920>`_.
61
62  .. code-block:: cpp
63
64      #include <pybind11/embed.h>
65      namespace py = pybind11;
66
67      int main() {
68          py::scoped_interpreter guard{}; // start the interpreter and keep it alive
69
70          py::print("Hello, World!"); // use the Python API
71      }
72
73* Support for inheriting from multiple C++ bases in Python.
74  `#693 <https://github.com/pybind/pybind11/pull/693>`_.
75
76  .. code-block:: python
77
78      from cpp_module import CppBase1, CppBase2
79
80      class PyDerived(CppBase1, CppBase2):
81          def __init__(self):
82              CppBase1.__init__(self)  # C++ bases must be initialized explicitly
83              CppBase2.__init__(self)
84
85* ``PYBIND11_MODULE`` is now the preferred way to create module entry points.
86  ``PYBIND11_PLUGIN`` is deprecated. See :ref:`macros` for details.
87  `#879 <https://github.com/pybind/pybind11/pull/879>`_.
88
89  .. code-block:: cpp
90
91      // new
92      PYBIND11_MODULE(example, m) {
93          m.def("add", [](int a, int b) { return a + b; });
94      }
95
96      // old
97      PYBIND11_PLUGIN(example) {
98          py::module m("example");
99          m.def("add", [](int a, int b) { return a + b; });
100          return m.ptr();
101      }
102
103* pybind11's headers and build system now more strictly enforce hidden symbol
104  visibility for extension modules. This should be seamless for most users,
105  but see the :doc:`upgrade` if you use a custom build system.
106  `#995 <https://github.com/pybind/pybind11/pull/995>`_.
107
108* Support for ``py::module_local`` types which allow multiple modules to
109  export the same C++ types without conflicts. This is useful for opaque
110  types like ``std::vector<int>``. ``py::bind_vector`` and ``py::bind_map``
111  now default to ``py::module_local`` if their elements are builtins or
112  local types. See :ref:`module_local` for details.
113  `#949 <https://github.com/pybind/pybind11/pull/949>`_,
114  `#981 <https://github.com/pybind/pybind11/pull/981>`_,
115  `#995 <https://github.com/pybind/pybind11/pull/995>`_,
116  `#997 <https://github.com/pybind/pybind11/pull/997>`_.
117
118* Custom constructors can now be added very easily using lambdas or factory
119  functions which return a class instance by value, pointer or holder. This
120  supersedes the old placement-new ``__init__`` technique.
121  See :ref:`custom_constructors` for details.
122  `#805 <https://github.com/pybind/pybind11/pull/805>`_,
123  `#1014 <https://github.com/pybind/pybind11/pull/1014>`_.
124
125  .. code-block:: cpp
126
127      struct Example {
128          Example(std::string);
129      };
130
131      py::class_<Example>(m, "Example")
132          .def(py::init<std::string>()) // existing constructor
133          .def(py::init([](int n) { // custom constructor
134              return std::make_unique<Example>(std::to_string(n));
135          }));
136
137* Similarly to custom constructors, pickling support functions are now bound
138  using the ``py::pickle()`` adaptor which improves type safety. See the
139  :doc:`upgrade` and :ref:`pickling` for details.
140  `#1038 <https://github.com/pybind/pybind11/pull/1038>`_.
141
142* Builtin support for converting C++17 standard library types and general
143  conversion improvements:
144
145  1. C++17 ``std::variant`` is supported right out of the box. C++11/14
146     equivalents (e.g. ``boost::variant``) can also be added with a simple
147     user-defined specialization. See :ref:`cpp17_container_casters` for details.
148     `#811 <https://github.com/pybind/pybind11/pull/811>`_,
149     `#845 <https://github.com/pybind/pybind11/pull/845>`_,
150     `#989 <https://github.com/pybind/pybind11/pull/989>`_.
151
152  2. Out-of-the-box support for C++17 ``std::string_view``.
153     `#906 <https://github.com/pybind/pybind11/pull/906>`_.
154
155  3. Improved compatibility of the builtin ``optional`` converter.
156     `#874 <https://github.com/pybind/pybind11/pull/874>`_.
157
158  4. The ``bool`` converter now accepts ``numpy.bool_`` and types which
159     define ``__bool__`` (Python 3.x) or ``__nonzero__`` (Python 2.7).
160     `#925 <https://github.com/pybind/pybind11/pull/925>`_.
161
162  5. C++-to-Python casters are now more efficient and move elements out
163     of rvalue containers whenever possible.
164     `#851 <https://github.com/pybind/pybind11/pull/851>`_,
165     `#936 <https://github.com/pybind/pybind11/pull/936>`_,
166     `#938 <https://github.com/pybind/pybind11/pull/938>`_.
167
168  6. Fixed ``bytes`` to ``std::string/char*`` conversion on Python 3.
169     `#817 <https://github.com/pybind/pybind11/pull/817>`_.
170
171  7. Fixed lifetime of temporary C++ objects created in Python-to-C++ conversions.
172     `#924 <https://github.com/pybind/pybind11/pull/924>`_.
173
174* Scope guard call policy for RAII types, e.g. ``py::call_guard<py::gil_scoped_release>()``,
175  ``py::call_guard<py::scoped_ostream_redirect>()``. See :ref:`call_policies` for details.
176  `#740 <https://github.com/pybind/pybind11/pull/740>`_.
177
178* Utility for redirecting C++ streams to Python (e.g. ``std::cout`` ->
179  ``sys.stdout``). Scope guard ``py::scoped_ostream_redirect`` in C++ and
180  a context manager in Python. See :ref:`ostream_redirect`.
181  `#1009 <https://github.com/pybind/pybind11/pull/1009>`_.
182
183* Improved handling of types and exceptions across module boundaries.
184  `#915 <https://github.com/pybind/pybind11/pull/915>`_,
185  `#951 <https://github.com/pybind/pybind11/pull/951>`_,
186  `#995 <https://github.com/pybind/pybind11/pull/995>`_.
187
188* Fixed destruction order of ``py::keep_alive`` nurse/patient objects
189  in reference cycles.
190  `#856 <https://github.com/pybind/pybind11/pull/856>`_.
191
192* Numpy and buffer protocol related improvements:
193
194  1. Support for negative strides in Python buffer objects/numpy arrays. This
195     required changing integers from unsigned to signed for the related C++ APIs.
196     Note: If you have compiler warnings enabled, you may notice some new conversion
197     warnings after upgrading. These can be resolved with ``static_cast``.
198     `#782 <https://github.com/pybind/pybind11/pull/782>`_.
199
200  2. Support ``std::complex`` and arrays inside ``PYBIND11_NUMPY_DTYPE``.
201     `#831 <https://github.com/pybind/pybind11/pull/831>`_,
202     `#832 <https://github.com/pybind/pybind11/pull/832>`_.
203
204  3. Support for constructing ``py::buffer_info`` and ``py::arrays`` using
205     arbitrary containers or iterators instead of requiring a ``std::vector``.
206     `#788 <https://github.com/pybind/pybind11/pull/788>`_,
207     `#822 <https://github.com/pybind/pybind11/pull/822>`_,
208     `#860 <https://github.com/pybind/pybind11/pull/860>`_.
209
210  4. Explicitly check numpy version and require >= 1.7.0.
211     `#819 <https://github.com/pybind/pybind11/pull/819>`_.
212
213* Support for allowing/prohibiting ``None`` for specific arguments and improved
214  ``None`` overload resolution order. See :ref:`none_arguments` for details.
215  `#843 <https://github.com/pybind/pybind11/pull/843>`_.
216  `#859 <https://github.com/pybind/pybind11/pull/859>`_.
217
218* Added ``py::exec()`` as a shortcut for ``py::eval<py::eval_statements>()``
219  and support for C++11 raw string literals as input. See :ref:`eval`.
220  `#766 <https://github.com/pybind/pybind11/pull/766>`_,
221  `#827 <https://github.com/pybind/pybind11/pull/827>`_.
222
223* ``py::vectorize()`` ignores non-vectorizable arguments and supports
224  member functions.
225  `#762 <https://github.com/pybind/pybind11/pull/762>`_.
226
227* Support for bound methods as callbacks (``pybind11/functional.h``).
228  `#815 <https://github.com/pybind/pybind11/pull/815>`_.
229
230* Allow aliasing pybind11 methods: ``cls.attr("foo") = cls.attr("bar")``.
231  `#802 <https://github.com/pybind/pybind11/pull/802>`_.
232
233* Don't allow mixed static/non-static overloads.
234  `#804 <https://github.com/pybind/pybind11/pull/804>`_.
235
236* Fixed overriding static properties in derived classes.
237  `#784 <https://github.com/pybind/pybind11/pull/784>`_.
238
239* Improved deduction of member functions of a derived class when its bases
240  aren't registered with pybind11.
241  `#855 <https://github.com/pybind/pybind11/pull/855>`_.
242
243  .. code-block:: cpp
244
245      struct Base {
246          int foo() { return 42; }
247      }
248
249      struct Derived : Base {}
250
251      // Now works, but previously required also binding `Base`
252      py::class_<Derived>(m, "Derived")
253          .def("foo", &Derived::foo); // function is actually from `Base`
254
255* The implementation of ``py::init<>`` now uses C++11 brace initialization
256  syntax to construct instances, which permits binding implicit constructors of
257  aggregate types. `#1015 <https://github.com/pybind/pybind11/pull/1015>`_.
258
259    .. code-block:: cpp
260
261        struct Aggregate {
262            int a;
263            std::string b;
264        };
265
266        py::class_<Aggregate>(m, "Aggregate")
267            .def(py::init<int, const std::string &>());
268
269* Fixed issues with multiple inheritance with offset base/derived pointers.
270  `#812 <https://github.com/pybind/pybind11/pull/812>`_,
271  `#866 <https://github.com/pybind/pybind11/pull/866>`_,
272  `#960 <https://github.com/pybind/pybind11/pull/960>`_.
273
274* Fixed reference leak of type objects.
275  `#1030 <https://github.com/pybind/pybind11/pull/1030>`_.
276
277* Improved support for the ``/std:c++14`` and ``/std:c++latest`` modes
278  on MSVC 2017.
279  `#841 <https://github.com/pybind/pybind11/pull/841>`_,
280  `#999 <https://github.com/pybind/pybind11/pull/999>`_.
281
282* Fixed detection of private operator new on MSVC.
283  `#893 <https://github.com/pybind/pybind11/pull/893>`_,
284  `#918 <https://github.com/pybind/pybind11/pull/918>`_.
285
286* Intel C++ compiler compatibility fixes.
287  `#937 <https://github.com/pybind/pybind11/pull/937>`_.
288
289* Fixed implicit conversion of `py::enum_` to integer types on Python 2.7.
290  `#821 <https://github.com/pybind/pybind11/pull/821>`_.
291
292* Added ``py::hash`` to fetch the hash value of Python objects, and
293  ``.def(hash(py::self))`` to provide the C++ ``std::hash`` as the Python
294  ``__hash__`` method.
295  `#1034 <https://github.com/pybind/pybind11/pull/1034>`_.
296
297* Fixed ``__truediv__`` on Python 2 and ``__itruediv__`` on Python 3.
298  `#867 <https://github.com/pybind/pybind11/pull/867>`_.
299
300* ``py::capsule`` objects now support the ``name`` attribute. This is useful
301  for interfacing with ``scipy.LowLevelCallable``.
302  `#902 <https://github.com/pybind/pybind11/pull/902>`_.
303
304* Fixed ``py::make_iterator``'s ``__next__()`` for past-the-end calls.
305  `#897 <https://github.com/pybind/pybind11/pull/897>`_.
306
307* Added ``error_already_set::matches()`` for checking Python exceptions.
308  `#772 <https://github.com/pybind/pybind11/pull/772>`_.
309
310* Deprecated ``py::error_already_set::clear()``. It's no longer needed
311  following a simplification of the ``py::error_already_set`` class.
312  `#954 <https://github.com/pybind/pybind11/pull/954>`_.
313
314* Deprecated ``py::handle::operator==()`` in favor of ``py::handle::is()``
315  `#825 <https://github.com/pybind/pybind11/pull/825>`_.
316
317* Deprecated ``py::object::borrowed``/``py::object::stolen``.
318  Use ``py::object::borrowed_t{}``/``py::object::stolen_t{}`` instead.
319  `#771 <https://github.com/pybind/pybind11/pull/771>`_.
320
321* Changed internal data structure versioning to avoid conflicts between
322  modules compiled with different revisions of pybind11.
323  `#1012 <https://github.com/pybind/pybind11/pull/1012>`_.
324
325* Additional compile-time and run-time error checking and more informative messages.
326  `#786 <https://github.com/pybind/pybind11/pull/786>`_,
327  `#794 <https://github.com/pybind/pybind11/pull/794>`_,
328  `#803 <https://github.com/pybind/pybind11/pull/803>`_.
329
330* Various minor improvements and fixes.
331  `#764 <https://github.com/pybind/pybind11/pull/764>`_,
332  `#791 <https://github.com/pybind/pybind11/pull/791>`_,
333  `#795 <https://github.com/pybind/pybind11/pull/795>`_,
334  `#840 <https://github.com/pybind/pybind11/pull/840>`_,
335  `#844 <https://github.com/pybind/pybind11/pull/844>`_,
336  `#846 <https://github.com/pybind/pybind11/pull/846>`_,
337  `#849 <https://github.com/pybind/pybind11/pull/849>`_,
338  `#858 <https://github.com/pybind/pybind11/pull/858>`_,
339  `#862 <https://github.com/pybind/pybind11/pull/862>`_,
340  `#871 <https://github.com/pybind/pybind11/pull/871>`_,
341  `#872 <https://github.com/pybind/pybind11/pull/872>`_,
342  `#881 <https://github.com/pybind/pybind11/pull/881>`_,
343  `#888 <https://github.com/pybind/pybind11/pull/888>`_,
344  `#899 <https://github.com/pybind/pybind11/pull/899>`_,
345  `#928 <https://github.com/pybind/pybind11/pull/928>`_,
346  `#931 <https://github.com/pybind/pybind11/pull/931>`_,
347  `#944 <https://github.com/pybind/pybind11/pull/944>`_,
348  `#950 <https://github.com/pybind/pybind11/pull/950>`_,
349  `#952 <https://github.com/pybind/pybind11/pull/952>`_,
350  `#962 <https://github.com/pybind/pybind11/pull/962>`_,
351  `#965 <https://github.com/pybind/pybind11/pull/965>`_,
352  `#970 <https://github.com/pybind/pybind11/pull/970>`_,
353  `#978 <https://github.com/pybind/pybind11/pull/978>`_,
354  `#979 <https://github.com/pybind/pybind11/pull/979>`_,
355  `#986 <https://github.com/pybind/pybind11/pull/986>`_,
356  `#1020 <https://github.com/pybind/pybind11/pull/1020>`_,
357  `#1027 <https://github.com/pybind/pybind11/pull/1027>`_,
358  `#1037 <https://github.com/pybind/pybind11/pull/1037>`_.
359
360* Testing improvements.
361  `#798 <https://github.com/pybind/pybind11/pull/798>`_,
362  `#882 <https://github.com/pybind/pybind11/pull/882>`_,
363  `#898 <https://github.com/pybind/pybind11/pull/898>`_,
364  `#900 <https://github.com/pybind/pybind11/pull/900>`_,
365  `#921 <https://github.com/pybind/pybind11/pull/921>`_,
366  `#923 <https://github.com/pybind/pybind11/pull/923>`_,
367  `#963 <https://github.com/pybind/pybind11/pull/963>`_.
368
369v2.1.1 (April 7, 2017)
370-----------------------------------------------------
371
372* Fixed minimum version requirement for MSVC 2015u3
373  `#773 <https://github.com/pybind/pybind11/pull/773>`_.
374
375v2.1.0 (March 22, 2017)
376-----------------------------------------------------
377
378* pybind11 now performs function overload resolution in two phases. The first
379  phase only considers exact type matches, while the second allows for implicit
380  conversions to take place. A special ``noconvert()`` syntax can be used to
381  completely disable implicit conversions for specific arguments.
382  `#643 <https://github.com/pybind/pybind11/pull/643>`_,
383  `#634 <https://github.com/pybind/pybind11/pull/634>`_,
384  `#650 <https://github.com/pybind/pybind11/pull/650>`_.
385
386* Fixed a regression where static properties no longer worked with classes
387  using multiple inheritance. The ``py::metaclass`` attribute is no longer
388  necessary (and deprecated as of this release) when binding classes with
389  static properties.
390  `#679 <https://github.com/pybind/pybind11/pull/679>`_,
391
392* Classes bound using ``pybind11`` can now use custom metaclasses.
393  `#679 <https://github.com/pybind/pybind11/pull/679>`_,
394
395* ``py::args`` and ``py::kwargs`` can now be mixed with other positional
396  arguments when binding functions using pybind11.
397  `#611 <https://github.com/pybind/pybind11/pull/611>`_.
398
399* Improved support for C++11 unicode string and character types; added
400  extensive documentation regarding pybind11's string conversion behavior.
401  `#624 <https://github.com/pybind/pybind11/pull/624>`_,
402  `#636 <https://github.com/pybind/pybind11/pull/636>`_,
403  `#715 <https://github.com/pybind/pybind11/pull/715>`_.
404
405* pybind11 can now avoid expensive copies when converting Eigen arrays to NumPy
406  arrays (and vice versa). `#610 <https://github.com/pybind/pybind11/pull/610>`_.
407
408* The "fast path" in ``py::vectorize`` now works for any full-size group of C or
409  F-contiguous arrays. The non-fast path is also faster since it no longer performs
410  copies of the input arguments (except when type conversions are necessary).
411  `#610 <https://github.com/pybind/pybind11/pull/610>`_.
412
413* Added fast, unchecked access to NumPy arrays via a proxy object.
414  `#746 <https://github.com/pybind/pybind11/pull/746>`_.
415
416* Transparent support for class-specific ``operator new`` and
417  ``operator delete`` implementations.
418  `#755 <https://github.com/pybind/pybind11/pull/755>`_.
419
420* Slimmer and more efficient STL-compatible iterator interface for sequence types.
421  `#662 <https://github.com/pybind/pybind11/pull/662>`_.
422
423* Improved custom holder type support.
424  `#607 <https://github.com/pybind/pybind11/pull/607>`_.
425
426* ``nullptr`` to ``None`` conversion fixed in various builtin type casters.
427  `#732 <https://github.com/pybind/pybind11/pull/732>`_.
428
429* ``enum_`` now exposes its members via a special ``__members__`` attribute.
430  `#666 <https://github.com/pybind/pybind11/pull/666>`_.
431
432* ``std::vector`` bindings created using ``stl_bind.h`` can now optionally
433  implement the buffer protocol. `#488 <https://github.com/pybind/pybind11/pull/488>`_.
434
435* Automated C++ reference documentation using doxygen and breathe.
436  `#598 <https://github.com/pybind/pybind11/pull/598>`_.
437
438* Added minimum compiler version assertions.
439  `#727 <https://github.com/pybind/pybind11/pull/727>`_.
440
441* Improved compatibility with C++1z.
442  `#677 <https://github.com/pybind/pybind11/pull/677>`_.
443
444* Improved ``py::capsule`` API. Can be used to implement cleanup
445  callbacks that are involved at module destruction time.
446  `#752 <https://github.com/pybind/pybind11/pull/752>`_.
447
448* Various minor improvements and fixes.
449  `#595 <https://github.com/pybind/pybind11/pull/595>`_,
450  `#588 <https://github.com/pybind/pybind11/pull/588>`_,
451  `#589 <https://github.com/pybind/pybind11/pull/589>`_,
452  `#603 <https://github.com/pybind/pybind11/pull/603>`_,
453  `#619 <https://github.com/pybind/pybind11/pull/619>`_,
454  `#648 <https://github.com/pybind/pybind11/pull/648>`_,
455  `#695 <https://github.com/pybind/pybind11/pull/695>`_,
456  `#720 <https://github.com/pybind/pybind11/pull/720>`_,
457  `#723 <https://github.com/pybind/pybind11/pull/723>`_,
458  `#729 <https://github.com/pybind/pybind11/pull/729>`_,
459  `#724 <https://github.com/pybind/pybind11/pull/724>`_,
460  `#742 <https://github.com/pybind/pybind11/pull/742>`_,
461  `#753 <https://github.com/pybind/pybind11/pull/753>`_.
462
463v2.0.1 (Jan 4, 2017)
464-----------------------------------------------------
465
466* Fix pointer to reference error in type_caster on MSVC
467  `#583 <https://github.com/pybind/pybind11/pull/583>`_.
468
469* Fixed a segmentation in the test suite due to a typo
470  `cd7eac <https://github.com/pybind/pybind11/commit/cd7eac>`_.
471
472v2.0.0 (Jan 1, 2017)
473-----------------------------------------------------
474
475* Fixed a reference counting regression affecting types with custom metaclasses
476  (introduced in v2.0.0-rc1).
477  `#571 <https://github.com/pybind/pybind11/pull/571>`_.
478
479* Quenched a CMake policy warning.
480  `#570 <https://github.com/pybind/pybind11/pull/570>`_.
481
482v2.0.0-rc1 (Dec 23, 2016)
483-----------------------------------------------------
484
485The pybind11 developers are excited to issue a release candidate of pybind11
486with a subsequent v2.0.0 release planned in early January next year.
487
488An incredible amount of effort by went into pybind11 over the last ~5 months,
489leading to a release that is jam-packed with exciting new features and numerous
490usability improvements. The following list links PRs or individual commits
491whenever applicable.
492
493Happy Christmas!
494
495* Support for binding C++ class hierarchies that make use of multiple
496  inheritance. `#410 <https://github.com/pybind/pybind11/pull/410>`_.
497
498* PyPy support: pybind11 now supports nightly builds of PyPy and will
499  interoperate with the future 5.7 release. No code changes are necessary,
500  everything "just" works as usual. Note that we only target the Python 2.7
501  branch for now; support for 3.x will be added once its ``cpyext`` extension
502  support catches up. A few minor features remain unsupported for the time
503  being (notably dynamic attributes in custom types).
504  `#527 <https://github.com/pybind/pybind11/pull/527>`_.
505
506* Significant work on the documentation -- in particular, the monolitic
507  ``advanced.rst`` file was restructured into a easier to read hierarchical
508  organization. `#448 <https://github.com/pybind/pybind11/pull/448>`_.
509
510* Many NumPy-related improvements:
511
512  1. Object-oriented API to access and modify NumPy ``ndarray`` instances,
513     replicating much of the corresponding NumPy C API functionality.
514     `#402 <https://github.com/pybind/pybind11/pull/402>`_.
515
516  2. NumPy array ``dtype`` array descriptors are now first-class citizens and
517     are exposed via a new class ``py::dtype``.
518
519  3. Structured dtypes can be registered using the ``PYBIND11_NUMPY_DTYPE()``
520     macro. Special ``array`` constructors accepting dtype objects were also
521     added.
522
523     One potential caveat involving this change: format descriptor strings
524     should now be accessed via ``format_descriptor::format()`` (however, for
525     compatibility purposes, the old syntax ``format_descriptor::value`` will
526     still work for non-structured data types). `#308
527     <https://github.com/pybind/pybind11/pull/308>`_.
528
529  4. Further improvements to support structured dtypes throughout the system.
530     `#472 <https://github.com/pybind/pybind11/pull/472>`_,
531     `#474 <https://github.com/pybind/pybind11/pull/474>`_,
532     `#459 <https://github.com/pybind/pybind11/pull/459>`_,
533     `#453 <https://github.com/pybind/pybind11/pull/453>`_,
534     `#452 <https://github.com/pybind/pybind11/pull/452>`_, and
535     `#505 <https://github.com/pybind/pybind11/pull/505>`_.
536
537  5. Fast access operators. `#497 <https://github.com/pybind/pybind11/pull/497>`_.
538
539  6. Constructors for arrays whose storage is owned by another object.
540     `#440 <https://github.com/pybind/pybind11/pull/440>`_.
541
542  7. Added constructors for ``array`` and ``array_t`` explicitly accepting shape
543     and strides; if strides are not provided, they are deduced assuming
544     C-contiguity. Also added simplified constructors for 1-dimensional case.
545
546  8. Added buffer/NumPy support for ``char[N]`` and ``std::array<char, N>`` types.
547
548  9. Added ``memoryview`` wrapper type which is constructible from ``buffer_info``.
549
550* Eigen: many additional conversions and support for non-contiguous
551  arrays/slices.
552  `#427 <https://github.com/pybind/pybind11/pull/427>`_,
553  `#315 <https://github.com/pybind/pybind11/pull/315>`_,
554  `#316 <https://github.com/pybind/pybind11/pull/316>`_,
555  `#312 <https://github.com/pybind/pybind11/pull/312>`_, and
556  `#267 <https://github.com/pybind/pybind11/pull/267>`_
557
558* Incompatible changes in ``class_<...>::class_()``:
559
560    1. Declarations of types that provide access via the buffer protocol must
561       now include the ``py::buffer_protocol()`` annotation as an argument to
562       the ``class_`` constructor.
563
564    2. Declarations of types that require a custom metaclass (i.e. all classes
565       which include static properties via commands such as
566       ``def_readwrite_static()``) must now include the ``py::metaclass()``
567       annotation as an argument to the ``class_`` constructor.
568
569       These two changes were necessary to make type definitions in pybind11
570       future-proof, and to support PyPy via its cpyext mechanism. `#527
571       <https://github.com/pybind/pybind11/pull/527>`_.
572
573
574    3. This version of pybind11 uses a redesigned mechnism for instantiating
575       trempoline classes that are used to override virtual methods from within
576       Python. This led to the following user-visible syntax change: instead of
577
578       .. code-block:: cpp
579
580           py::class_<TrampolineClass>("MyClass")
581             .alias<MyClass>()
582             ....
583
584       write
585
586       .. code-block:: cpp
587
588           py::class_<MyClass, TrampolineClass>("MyClass")
589             ....
590
591       Importantly, both the original and the trampoline class are now
592       specified as an arguments (in arbitrary order) to the ``py::class_``
593       template, and the ``alias<..>()`` call is gone. The new scheme has zero
594       overhead in cases when Python doesn't override any functions of the
595       underlying C++ class. `rev. 86d825
596       <https://github.com/pybind/pybind11/commit/86d825>`_.
597
598* Added ``eval`` and ``eval_file`` functions for evaluating expressions and
599  statements from a string or file. `rev. 0d3fc3
600  <https://github.com/pybind/pybind11/commit/0d3fc3>`_.
601
602* pybind11 can now create types with a modifiable dictionary.
603  `#437 <https://github.com/pybind/pybind11/pull/437>`_ and
604  `#444 <https://github.com/pybind/pybind11/pull/444>`_.
605
606* Support for translation of arbitrary C++ exceptions to Python counterparts.
607  `#296 <https://github.com/pybind/pybind11/pull/296>`_ and
608  `#273 <https://github.com/pybind/pybind11/pull/273>`_.
609
610* Report full backtraces through mixed C++/Python code, better reporting for
611  import errors, fixed GIL management in exception processing.
612  `#537 <https://github.com/pybind/pybind11/pull/537>`_,
613  `#494 <https://github.com/pybind/pybind11/pull/494>`_,
614  `rev. e72d95 <https://github.com/pybind/pybind11/commit/e72d95>`_, and
615  `rev. 099d6e <https://github.com/pybind/pybind11/commit/099d6e>`_.
616
617* Support for bit-level operations, comparisons, and serialization of C++
618  enumerations. `#503 <https://github.com/pybind/pybind11/pull/503>`_,
619  `#508 <https://github.com/pybind/pybind11/pull/508>`_,
620  `#380 <https://github.com/pybind/pybind11/pull/380>`_,
621  `#309 <https://github.com/pybind/pybind11/pull/309>`_.
622  `#311 <https://github.com/pybind/pybind11/pull/311>`_.
623
624* The ``class_`` constructor now accepts its template arguments in any order.
625  `#385 <https://github.com/pybind/pybind11/pull/385>`_.
626
627* Attribute and item accessors now have a more complete interface which makes
628  it possible to chain attributes as in
629  ``obj.attr("a")[key].attr("b").attr("method")(1, 2, 3)``. `#425
630  <https://github.com/pybind/pybind11/pull/425>`_.
631
632* Major redesign of the default and conversion constructors in ``pytypes.h``.
633  `#464 <https://github.com/pybind/pybind11/pull/464>`_.
634
635* Added built-in support for ``std::shared_ptr`` holder type. It is no longer
636  necessary to to include a declaration of the form
637  ``PYBIND11_DECLARE_HOLDER_TYPE(T, std::shared_ptr<T>)`` (though continuing to
638  do so won't cause an error).
639  `#454 <https://github.com/pybind/pybind11/pull/454>`_.
640
641* New ``py::overload_cast`` casting operator to select among multiple possible
642  overloads of a function. An example:
643
644    .. code-block:: cpp
645
646        py::class_<Pet>(m, "Pet")
647            .def("set", py::overload_cast<int>(&Pet::set), "Set the pet's age")
648            .def("set", py::overload_cast<const std::string &>(&Pet::set), "Set the pet's name");
649
650  This feature only works on C++14-capable compilers.
651  `#541 <https://github.com/pybind/pybind11/pull/541>`_.
652
653* C++ types are automatically cast to Python types, e.g. when assigning
654  them as an attribute. For instance, the following is now legal:
655
656    .. code-block:: cpp
657
658        py::module m = /* ... */
659        m.attr("constant") = 123;
660
661  (Previously, a ``py::cast`` call was necessary to avoid a compilation error.)
662  `#551 <https://github.com/pybind/pybind11/pull/551>`_.
663
664* Redesigned ``pytest``-based test suite. `#321 <https://github.com/pybind/pybind11/pull/321>`_.
665
666* Instance tracking to detect reference leaks in test suite. `#324 <https://github.com/pybind/pybind11/pull/324>`_
667
668* pybind11 can now distinguish between multiple different instances that are
669  located at the same memory address, but which have different types.
670  `#329 <https://github.com/pybind/pybind11/pull/329>`_.
671
672* Improved logic in ``move`` return value policy.
673  `#510 <https://github.com/pybind/pybind11/pull/510>`_,
674  `#297 <https://github.com/pybind/pybind11/pull/297>`_.
675
676* Generalized unpacking API to permit calling Python functions from C++ using
677  notation such as ``foo(a1, a2, *args, "ka"_a=1, "kb"_a=2, **kwargs)``. `#372 <https://github.com/pybind/pybind11/pull/372>`_.
678
679* ``py::print()`` function whose behavior matches that of the native Python
680  ``print()`` function. `#372 <https://github.com/pybind/pybind11/pull/372>`_.
681
682* Added ``py::dict`` keyword constructor:``auto d = dict("number"_a=42,
683  "name"_a="World");``. `#372 <https://github.com/pybind/pybind11/pull/372>`_.
684
685* Added ``py::str::format()`` method and ``_s`` literal: ``py::str s = "1 + 2
686  = {}"_s.format(3);``. `#372 <https://github.com/pybind/pybind11/pull/372>`_.
687
688* Added ``py::repr()`` function which is equivalent to Python's builtin
689  ``repr()``. `#333 <https://github.com/pybind/pybind11/pull/333>`_.
690
691* Improved construction and destruction logic for holder types. It is now
692  possible to reference instances with smart pointer holder types without
693  constructing the holder if desired. The ``PYBIND11_DECLARE_HOLDER_TYPE``
694  macro now accepts an optional second parameter to indicate whether the holder
695  type uses intrusive reference counting.
696  `#533 <https://github.com/pybind/pybind11/pull/533>`_ and
697  `#561 <https://github.com/pybind/pybind11/pull/561>`_.
698
699* Mapping a stateless C++ function to Python and back is now "for free" (i.e.
700  no extra indirections or argument conversion overheads). `rev. 954b79
701  <https://github.com/pybind/pybind11/commit/954b79>`_.
702
703* Bindings for ``std::valarray<T>``.
704  `#545 <https://github.com/pybind/pybind11/pull/545>`_.
705
706* Improved support for C++17 capable compilers.
707  `#562 <https://github.com/pybind/pybind11/pull/562>`_.
708
709* Bindings for ``std::optional<t>``.
710  `#475 <https://github.com/pybind/pybind11/pull/475>`_,
711  `#476 <https://github.com/pybind/pybind11/pull/476>`_,
712  `#479 <https://github.com/pybind/pybind11/pull/479>`_,
713  `#499 <https://github.com/pybind/pybind11/pull/499>`_, and
714  `#501 <https://github.com/pybind/pybind11/pull/501>`_.
715
716* ``stl_bind.h``: general improvements and support for ``std::map`` and
717  ``std::unordered_map``.
718  `#490 <https://github.com/pybind/pybind11/pull/490>`_,
719  `#282 <https://github.com/pybind/pybind11/pull/282>`_,
720  `#235 <https://github.com/pybind/pybind11/pull/235>`_.
721
722* The ``std::tuple``, ``std::pair``, ``std::list``, and ``std::vector`` type
723  casters now accept any Python sequence type as input. `rev. 107285
724  <https://github.com/pybind/pybind11/commit/107285>`_.
725
726* Improved CMake Python detection on multi-architecture Linux.
727  `#532 <https://github.com/pybind/pybind11/pull/532>`_.
728
729* Infrastructure to selectively disable or enable parts of the automatically
730  generated docstrings. `#486 <https://github.com/pybind/pybind11/pull/486>`_.
731
732* ``reference`` and ``reference_internal`` are now the default return value
733  properties for static and non-static properties, respectively. `#473
734  <https://github.com/pybind/pybind11/pull/473>`_. (the previous defaults
735  were ``automatic``). `#473 <https://github.com/pybind/pybind11/pull/473>`_.
736
737* Support for ``std::unique_ptr`` with non-default deleters or no deleter at
738  all (``py::nodelete``). `#384 <https://github.com/pybind/pybind11/pull/384>`_.
739
740* Deprecated ``handle::call()`` method. The new syntax to call Python
741  functions is simply ``handle()``. It can also be invoked explicitly via
742  ``handle::operator<X>()``, where ``X`` is an optional return value policy.
743
744* Print more informative error messages when ``make_tuple()`` or ``cast()``
745  fail. `#262 <https://github.com/pybind/pybind11/pull/262>`_.
746
747* Creation of holder types for classes deriving from
748  ``std::enable_shared_from_this<>`` now also works for ``const`` values.
749  `#260 <https://github.com/pybind/pybind11/pull/260>`_.
750
751* ``make_iterator()`` improvements for better compatibility with various
752  types (now uses prefix increment operator); it now also accepts iterators
753  with different begin/end types as long as they are equality comparable.
754  `#247 <https://github.com/pybind/pybind11/pull/247>`_.
755
756* ``arg()`` now accepts a wider range of argument types for default values.
757  `#244 <https://github.com/pybind/pybind11/pull/244>`_.
758
759* Support ``keep_alive`` where the nurse object may be ``None``. `#341
760  <https://github.com/pybind/pybind11/pull/341>`_.
761
762* Added constructors for ``str`` and ``bytes`` from zero-terminated char
763  pointers, and from char pointers and length. Added constructors for ``str``
764  from ``bytes`` and for ``bytes`` from ``str``, which will perform UTF-8
765  decoding/encoding as required.
766
767* Many other improvements of library internals without user-visible changes
768
769
7701.8.1 (July 12, 2016)
771----------------------
772* Fixed a rare but potentially very severe issue when the garbage collector ran
773  during pybind11 type creation.
774
7751.8.0 (June 14, 2016)
776----------------------
777* Redesigned CMake build system which exports a convenient
778  ``pybind11_add_module`` function to parent projects.
779* ``std::vector<>`` type bindings analogous to Boost.Python's ``indexing_suite``
780* Transparent conversion of sparse and dense Eigen matrices and vectors (``eigen.h``)
781* Added an ``ExtraFlags`` template argument to the NumPy ``array_t<>`` wrapper
782  to disable an enforced cast that may lose precision, e.g. to create overloads
783  for different precisions and complex vs real-valued matrices.
784* Prevent implicit conversion of floating point values to integral types in
785  function arguments
786* Fixed incorrect default return value policy for functions returning a shared
787  pointer
788* Don't allow registering a type via ``class_`` twice
789* Don't allow casting a ``None`` value into a C++ lvalue reference
790* Fixed a crash in ``enum_::operator==`` that was triggered by the ``help()`` command
791* Improved detection of whether or not custom C++ types can be copy/move-constructed
792* Extended ``str`` type to also work with ``bytes`` instances
793* Added a ``"name"_a`` user defined string literal that is equivalent to ``py::arg("name")``.
794* When specifying function arguments via ``py::arg``, the test that verifies
795  the number of arguments now runs at compile time.
796* Added ``[[noreturn]]`` attribute to ``pybind11_fail()`` to quench some
797  compiler warnings
798* List function arguments in exception text when the dispatch code cannot find
799  a matching overload
800* Added ``PYBIND11_OVERLOAD_NAME`` and ``PYBIND11_OVERLOAD_PURE_NAME`` macros which
801  can be used to override virtual methods whose name differs in C++ and Python
802  (e.g. ``__call__`` and ``operator()``)
803* Various minor ``iterator`` and ``make_iterator()`` improvements
804* Transparently support ``__bool__`` on Python 2.x and Python 3.x
805* Fixed issue with destructor of unpickled object not being called
806* Minor CMake build system improvements on Windows
807* New ``pybind11::args`` and ``pybind11::kwargs`` types to create functions which
808  take an arbitrary number of arguments and keyword arguments
809* New syntax to call a Python function from C++ using ``*args`` and ``*kwargs``
810* The functions ``def_property_*`` now correctly process docstring arguments (these
811  formerly caused a segmentation fault)
812* Many ``mkdoc.py`` improvements (enumerations, template arguments, ``DOC()``
813  macro accepts more arguments)
814* Cygwin support
815* Documentation improvements (pickling support, ``keep_alive``, macro usage)
816
8171.7 (April 30, 2016)
818----------------------
819* Added a new ``move`` return value policy that triggers C++11 move semantics.
820  The automatic return value policy falls back to this case whenever a rvalue
821  reference is encountered
822* Significantly more general GIL state routines that are used instead of
823  Python's troublesome ``PyGILState_Ensure`` and ``PyGILState_Release`` API
824* Redesign of opaque types that drastically simplifies their usage
825* Extended ability to pass values of type ``[const] void *``
826* ``keep_alive`` fix: don't fail when there is no patient
827* ``functional.h``: acquire the GIL before calling a Python function
828* Added Python RAII type wrappers ``none`` and ``iterable``
829* Added ``*args`` and ``*kwargs`` pass-through parameters to
830  ``pybind11.get_include()`` function
831* Iterator improvements and fixes
832* Documentation on return value policies and opaque types improved
833
8341.6 (April 30, 2016)
835----------------------
836* Skipped due to upload to PyPI gone wrong and inability to recover
837  (https://github.com/pypa/packaging-problems/issues/74)
838
8391.5 (April 21, 2016)
840----------------------
841* For polymorphic types, use RTTI to try to return the closest type registered with pybind11
842* Pickling support for serializing and unserializing C++ instances to a byte stream in Python
843* Added a convenience routine ``make_iterator()`` which turns a range indicated
844  by a pair of C++ iterators into a iterable Python object
845* Added ``len()`` and a variadic ``make_tuple()`` function
846* Addressed a rare issue that could confuse the current virtual function
847  dispatcher and another that could lead to crashes in multi-threaded
848  applications
849* Added a ``get_include()`` function to the Python module that returns the path
850  of the directory containing the installed pybind11 header files
851* Documentation improvements: import issues, symbol visibility, pickling, limitations
852* Added casting support for ``std::reference_wrapper<>``
853
8541.4 (April 7, 2016)
855--------------------------
856* Transparent type conversion for ``std::wstring`` and ``wchar_t``
857* Allow passing ``nullptr``-valued strings
858* Transparent passing of ``void *`` pointers using capsules
859* Transparent support for returning values wrapped in ``std::unique_ptr<>``
860* Improved docstring generation for compatibility with Sphinx
861* Nicer debug error message when default parameter construction fails
862* Support for "opaque" types that bypass the transparent conversion layer for STL containers
863* Redesigned type casting interface to avoid ambiguities that could occasionally cause compiler errors
864* Redesigned property implementation; fixes crashes due to an unfortunate default return value policy
865* Anaconda package generation support
866
8671.3 (March 8, 2016)
868--------------------------
869
870* Added support for the Intel C++ compiler (v15+)
871* Added support for the STL unordered set/map data structures
872* Added support for the STL linked list data structure
873* NumPy-style broadcasting support in ``pybind11::vectorize``
874* pybind11 now displays more verbose error messages when ``arg::operator=()`` fails
875* pybind11 internal data structures now live in a version-dependent namespace to avoid ABI issues
876* Many, many bugfixes involving corner cases and advanced usage
877
8781.2 (February 7, 2016)
879--------------------------
880
881* Optional: efficient generation of function signatures at compile time using C++14
882* Switched to a simpler and more general way of dealing with function default
883  arguments. Unused keyword arguments in function calls are now detected and
884  cause errors as expected
885* New ``keep_alive`` call policy analogous to Boost.Python's ``with_custodian_and_ward``
886* New ``pybind11::base<>`` attribute to indicate a subclass relationship
887* Improved interface for RAII type wrappers in ``pytypes.h``
888* Use RAII type wrappers consistently within pybind11 itself. This
889  fixes various potential refcount leaks when exceptions occur
890* Added new ``bytes`` RAII type wrapper (maps to ``string`` in Python 2.7)
891* Made handle and related RAII classes const correct, using them more
892  consistently everywhere now
893* Got rid of the ugly ``__pybind11__`` attributes on the Python side---they are
894  now stored in a C++ hash table that is not visible in Python
895* Fixed refcount leaks involving NumPy arrays and bound functions
896* Vastly improved handling of shared/smart pointers
897* Removed an unnecessary copy operation in ``pybind11::vectorize``
898* Fixed naming clashes when both pybind11 and NumPy headers are included
899* Added conversions for additional exception types
900* Documentation improvements (using multiple extension modules, smart pointers,
901  other minor clarifications)
902* unified infrastructure for parsing variadic arguments in ``class_`` and cpp_function
903* Fixed license text (was: ZLIB, should have been: 3-clause BSD)
904* Python 3.2 compatibility
905* Fixed remaining issues when accessing types in another plugin module
906* Added enum comparison and casting methods
907* Improved SFINAE-based detection of whether types are copy-constructible
908* Eliminated many warnings about unused variables and the use of ``offsetof()``
909* Support for ``std::array<>`` conversions
910
9111.1 (December 7, 2015)
912--------------------------
913
914* Documentation improvements (GIL, wrapping functions, casting, fixed many typos)
915* Generalized conversion of integer types
916* Improved support for casting function objects
917* Improved support for ``std::shared_ptr<>`` conversions
918* Initial support for ``std::set<>`` conversions
919* Fixed type resolution issue for types defined in a separate plugin module
920* Cmake build system improvements
921* Factored out generic functionality to non-templated code (smaller code size)
922* Added a code size / compile time benchmark vs Boost.Python
923* Added an appveyor CI script
924
9251.0 (October 15, 2015)
926------------------------
927* Initial release
928