ext/pybind11/docs/changelog.rst

   1 .. _changelog:
   2
   3 Changelog
   4 #########
   5
   6 Starting with version 1.8.0, pybind11 releases use a `semantic versioning
   7 <http://semver.org>`_ policy.
   8
   9 v2.3.0 (Not yet released)
  10 -----------------------------------------------------
  11
  12 * TBD
  13
  14 v2.2.1 (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
  51 v2.2.0 (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
 369 v2.1.1 (April 7, 2017)
 370 -----------------------------------------------------
 371
 372 * Fixed minimum version requirement for MSVC 2015u3
 373   `#773 <https://github.com/pybind/pybind11/pull/773>`_.
 374
 375 v2.1.0 (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
 463 v2.0.1 (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
 472 v2.0.0 (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
 482 v2.0.0-rc1 (Dec 23, 2016)
 483 -----------------------------------------------------
 484
 485 The pybind11 developers are excited to issue a release candidate of pybind11
 486 with a subsequent v2.0.0 release planned in early January next year.
 487
 488 An incredible amount of effort by went into pybind11 over the last ~5 months,
 489 leading to a release that is jam-packed with exciting new features and numerous
 490 usability improvements. The following list links PRs or individual commits
 491 whenever applicable.
 492
 493 Happy 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
 770 1.8.1 (July 12, 2016)
 771 ----------------------
 772 * Fixed a rare but potentially very severe issue when the garbage collector ran
 773   during pybind11 type creation.
 774
 775 1.8.0 (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
 817 1.7 (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
 834 1.6 (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
 839 1.5 (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
 854 1.4 (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
 867 1.3 (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
 878 1.2 (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
 911 1.1 (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
 925 1.0 (October 15, 2015)
 926 ------------------------
 927 * Initial release