.. _changelog:

Changelog

#########

Starting with version 1.8.0, pybind11 releases use a `semantic versioning

<http://semver.org>`_ policy.

v2.4.3 (Oct 15, 2019)

-----------------------------------------------------

* Adapt pybind11 to a C API convention change in Python 3.8. `#1950

  <https://github.com/pybind/pybind11/pull/1950>`_.

v2.4.2 (Sep 21, 2019)

-----------------------------------------------------

* Replaced usage of a C++14 only construct. `#1929

  <https://github.com/pybind/pybind11/pull/1929>`_.

* Made an ifdef future-proof for Python >= 4. `f3109d

  <https://github.com/pybind/pybind11/commit/f3109d>`_.

v2.4.1 (Sep 20, 2019)

-----------------------------------------------------

* Fixed a problem involving implicit conversion from enumerations to integers

  on Python 3.8. `#1780 <https://github.com/pybind/pybind11/pull/1780>`_.

v2.4.0 (Sep 19, 2019)

-----------------------------------------------------

* Try harder to keep pybind11-internal data structures separate when there

  are potential ABI incompatibilities. Fixes crashes that occurred when loading

  multiple pybind11 extensions that were e.g. compiled by GCC (libstdc++)

  and Clang (libc++).

  `#1588 <https://github.com/pybind/pybind11/pull/1588>`_ and

  `c9f5a <https://github.com/pybind/pybind11/commit/c9f5a>`_.

* Added support for ``__await__``, ``__aiter__``, and ``__anext__`` protocols.

  `#1842 <https://github.com/pybind/pybind11/pull/1842>`_.

* ``pybind11_add_module()``: don't strip symbols when compiling in

  ``RelWithDebInfo`` mode. `#1980

  <https://github.com/pybind/pybind11/pull/1980>`_.

* ``enum_``: Reproduce Python behavior when comparing against invalid values

  (e.g. ``None``, strings, etc.). Add back support for ``__invert__()``.

  `#1912 <https://github.com/pybind/pybind11/pull/1912>`_,

  `#1907 <https://github.com/pybind/pybind11/pull/1907>`_.

* List insertion operation for ``py::list``.

  Added ``.empty()`` to all collection types.

  Added ``py::set::contains()`` and ``py::dict::contains()``.

  `#1887 <https://github.com/pybind/pybind11/pull/1887>`_,

  `#1884 <https://github.com/pybind/pybind11/pull/1884>`_,

  `#1888 <https://github.com/pybind/pybind11/pull/1888>`_.

* ``py::details::overload_cast_impl`` is available in C++11 mode, can be used

  like ``overload_cast`` with an additional set of parantheses.

  `#1581 <https://github.com/pybind/pybind11/pull/1581>`_.

* Fixed ``get_include()`` on Conda.

  `#1877 <https://github.com/pybind/pybind11/pull/1877>`_.

* ``stl_bind.h``: negative indexing support.

  `#1882 <https://github.com/pybind/pybind11/pull/1882>`_.

* Minor CMake fix to add MinGW compatibility.

  `#1851 <https://github.com/pybind/pybind11/pull/1851>`_.

* GIL-related fixes.

  `#1836 <https://github.com/pybind/pybind11/pull/1836>`_,

  `8b90b <https://github.com/pybind/pybind11/commit/8b90b>`_.

* Other very minor/subtle fixes and improvements.

  `#1329 <https://github.com/pybind/pybind11/pull/1329>`_,

  `#1910 <https://github.com/pybind/pybind11/pull/1910>`_,

  `#1863 <https://github.com/pybind/pybind11/pull/1863>`_,

  `#1847 <https://github.com/pybind/pybind11/pull/1847>`_,

  `#1890 <https://github.com/pybind/pybind11/pull/1890>`_,

  `#1860 <https://github.com/pybind/pybind11/pull/1860>`_,

  `#1848 <https://github.com/pybind/pybind11/pull/1848>`_,

  `#1821 <https://github.com/pybind/pybind11/pull/1821>`_,

  `#1837 <https://github.com/pybind/pybind11/pull/1837>`_,

  `#1833 <https://github.com/pybind/pybind11/pull/1833>`_,

  `#1748 <https://github.com/pybind/pybind11/pull/1748>`_,

  `#1852 <https://github.com/pybind/pybind11/pull/1852>`_.

v2.3.0 (June 11, 2019)

-----------------------------------------------------

* Significantly reduced module binary size (10-20%) when compiled in C++11 mode

  with GCC/Clang, or in any mode with MSVC. Function signatures are now always

  precomputed at compile time (this was previously only available in C++14 mode

  for non-MSVC compilers).

  `#934 <https://github.com/pybind/pybind11/pull/934>`_.

* Add basic support for tag-based static polymorphism, where classes

  provide a method to returns the desired type of an instance.

  `#1326 <https://github.com/pybind/pybind11/pull/1326>`_.

* Python type wrappers (``py::handle``, ``py::object``, etc.)

  now support map Python's number protocol onto C++ arithmetic

  operators such as ``operator+``, ``operator/=``, etc.

  `#1511 <https://github.com/pybind/pybind11/pull/1511>`_.

* A number of improvements related to enumerations:

   1. The ``enum_`` implementation was rewritten from scratch to reduce

      code bloat. Rather than instantiating a full implementation for each

      enumeration, most code is now contained in a generic base class.

      `#1511 <https://github.com/pybind/pybind11/pull/1511>`_.

   2. The ``value()``  method of ``py::enum_`` now accepts an optional

      docstring that will be shown in the documentation of the associated

      enumeration. `#1160 <https://github.com/pybind/pybind11/pull/1160>`_.

   3. check for already existing enum value and throw an error if present.

      `#1453 <https://github.com/pybind/pybind11/pull/1453>`_.

* Support for over-aligned type allocation via C++17's aligned ``new``

  statement. `#1582 <https://github.com/pybind/pybind11/pull/1582>`_.

* Added ``py::ellipsis()`` method for slicing of multidimensional NumPy arrays

  `#1502 <https://github.com/pybind/pybind11/pull/1502>`_.

* Numerous Improvements to the ``mkdoc.py`` script for extracting documentation

  from C++ header files.

  `#1788 <https://github.com/pybind/pybind11/pull/1788>`_.

* ``pybind11_add_module()``: allow including Python as a ``SYSTEM`` include path.

  `#1416 <https://github.com/pybind/pybind11/pull/1416>`_.

* ``pybind11/stl.h`` does not convert strings to ``vector<string>`` anymore.

  `#1258 <https://github.com/pybind/pybind11/issues/1258>`_.

* Mark static methods as such to fix auto-generated Sphinx documentation.

  `#1732 <https://github.com/pybind/pybind11/pull/1732>`_.

* Re-throw forced unwind exceptions (e.g. during pthread termination).

  `#1208 <https://github.com/pybind/pybind11/pull/1208>`_.

* Added ``__contains__`` method to the bindings of maps (``std::map``,

  ``std::unordered_map``).

  `#1767 <https://github.com/pybind/pybind11/pull/1767>`_.

* Improvements to ``gil_scoped_acquire``.

  `#1211 <https://github.com/pybind/pybind11/pull/1211>`_.

* Type caster support for ``std::deque<T>``.

  `#1609 <https://github.com/pybind/pybind11/pull/1609>`_.

* Support for ``std::unique_ptr`` holders, whose deleters differ between a base and derived

  class. `#1353 <https://github.com/pybind/pybind11/pull/1353>`_.

* Construction of STL array/vector-like data structures from

  iterators. Added an ``extend()`` operation.

  `#1709 <https://github.com/pybind/pybind11/pull/1709>`_,

* CMake build system improvements for projects that include non-C++

  files (e.g. plain C, CUDA) in ``pybind11_add_module`` et al.

  `#1678 <https://github.com/pybind/pybind11/pull/1678>`_.

* Fixed asynchronous invocation and deallocation of Python functions

  wrapped in ``std::function``.

  `#1595 <https://github.com/pybind/pybind11/pull/1595>`_.

* Fixes regarding return value policy propagation in STL type casters.

  `#1603 <https://github.com/pybind/pybind11/pull/1603>`_.

* Fixed scoped enum comparisons.

  `#1571 <https://github.com/pybind/pybind11/pull/1571>`_.

* Fixed iostream redirection for code that releases the GIL.

  `#1368 <https://github.com/pybind/pybind11/pull/1368>`_,

* A number of CI-related fixes.

  `#1757 <https://github.com/pybind/pybind11/pull/1757>`_,

  `#1744 <https://github.com/pybind/pybind11/pull/1744>`_,

  `#1670 <https://github.com/pybind/pybind11/pull/1670>`_.

v2.2.4 (September 11, 2018)

-----------------------------------------------------

* Use new Python 3.7 Thread Specific Storage (TSS) implementation if available.

  `#1454 <https://github.com/pybind/pybind11/pull/1454>`_,

  `#1517 <https://github.com/pybind/pybind11/pull/1517>`_.

* Fixes for newer MSVC versions and C++17 mode.

  `#1347 <https://github.com/pybind/pybind11/pull/1347>`_,

  `#1462 <https://github.com/pybind/pybind11/pull/1462>`_.

* Propagate return value policies to type-specific casters

  when casting STL containers.

  `#1455 <https://github.com/pybind/pybind11/pull/1455>`_.

* Allow ostream-redirection of more than 1024 characters.

  `#1479 <https://github.com/pybind/pybind11/pull/1479>`_.

* Set ``Py_DEBUG`` define when compiling against a debug Python build.

  `#1438 <https://github.com/pybind/pybind11/pull/1438>`_.

* Untangle integer logic in number type caster to work for custom

  types that may only be castable to a restricted set of builtin types.

  `#1442 <https://github.com/pybind/pybind11/pull/1442>`_.

* CMake build system: Remember Python version in cache file.

  `#1434 <https://github.com/pybind/pybind11/pull/1434>`_.

* Fix for custom smart pointers: use ``std::addressof`` to obtain holder

  address instead of ``operator&``.

  `#1435 <https://github.com/pybind/pybind11/pull/1435>`_.

* Properly report exceptions thrown during module initialization.

  `#1362 <https://github.com/pybind/pybind11/pull/1362>`_.

* Fixed a segmentation fault when creating empty-shaped NumPy array.

  `#1371 <https://github.com/pybind/pybind11/pull/1371>`_.

* The version of Intel C++ compiler must be >= 2017, and this is now checked by

  the header files. `#1363 <https://github.com/pybind/pybind11/pull/1363>`_.

* A few minor typo fixes and improvements to the test suite, and

  patches that silence compiler warnings.

* Vectors now support construction from generators, as well as ``extend()`` from a

  list or generator.

  `#1496 <https://github.com/pybind/pybind11/pull/1496>`_.

v2.2.3 (April 29, 2018)

-----------------------------------------------------

* The pybind11 header location detection was replaced by a new implementation

  that no longer depends on ``pip`` internals (the recently released ``pip``

  10 has restricted access to this API).

  `#1190 <https://github.com/pybind/pybind11/pull/1190>`_.

* Small adjustment to an implementation detail to work around a compiler segmentation fault in Clang 3.3/3.4.

  `#1350 <https://github.com/pybind/pybind11/pull/1350>`_.

* The minimal supported version of the Intel compiler was >= 17.0 since

  pybind11 v2.1. This check is now explicit, and a compile-time error is raised

  if the compiler meet the requirement.

  `#1363 <https://github.com/pybind/pybind11/pull/1363>`_.

* Fixed an endianness-related fault in the test suite.

  `#1287 <https://github.com/pybind/pybind11/pull/1287>`_.

v2.2.2 (February 7, 2018)

-----------------------------------------------------

* Fixed a segfault when combining embedded interpreter

  shutdown/reinitialization with external loaded pybind11 modules.

  `#1092 <https://github.com/pybind/pybind11/pull/1092>`_.

* Eigen support: fixed a bug where Nx1/1xN numpy inputs couldn't be passed as

  arguments to Eigen vectors (which for Eigen are simply compile-time fixed

  Nx1/1xN matrices).

  `#1106 <https://github.com/pybind/pybind11/pull/1106>`_.

* Clarified to license by moving the licensing of contributions from

  ``LICENSE`` into ``CONTRIBUTING.md``: the licensing of contributions is not

  actually part of the software license as distributed.  This isn't meant to be

  a substantial change in the licensing of the project, but addresses concerns

  that the clause made the license non-standard.

  `#1109 <https://github.com/pybind/pybind11/issues/1109>`_.

* Fixed a regression introduced in 2.1 that broke binding functions with lvalue

  character literal arguments.

  `#1128 <https://github.com/pybind/pybind11/pull/1128>`_.

* MSVC: fix for compilation failures under /permissive-, and added the flag to

  the appveyor test suite.

  `#1155 <https://github.com/pybind/pybind11/pull/1155>`_.

* Fixed ``__qualname__`` generation, and in turn, fixes how class names

  (especially nested class names) are shown in generated docstrings.

  `#1171 <https://github.com/pybind/pybind11/pull/1171>`_.

* Updated the FAQ with a suggested project citation reference.

  `#1189 <https://github.com/pybind/pybind11/pull/1189>`_.

* Added fixes for deprecation warnings when compiled under C++17 with

  ``-Wdeprecated`` turned on, and add ``-Wdeprecated`` to the test suite

  compilation flags.

  `#1191 <https://github.com/pybind/pybind11/pull/1191>`_.

* Fixed outdated PyPI URLs in ``setup.py``.

  `#1213 <https://github.com/pybind/pybind11/pull/1213>`_.

* Fixed a refcount leak for arguments that end up in a ``py::args`` argument

  for functions with both fixed positional and ``py::args`` arguments.

  `#1216 <https://github.com/pybind/pybind11/pull/1216>`_.

* Fixed a potential segfault resulting from possible premature destruction of

  ``py::args``/``py::kwargs`` arguments with overloaded functions.

  `#1223 <https://github.com/pybind/pybind11/pull/1223>`_.

* Fixed ``del map[item]`` for a ``stl_bind.h`` bound stl map.

  `#1229 <https://github.com/pybind/pybind11/pull/1229>`_.

* Fixed a regression from v2.1.x where the aggregate initialization could

  unintentionally end up at a constructor taking a templated

  ``std::initializer_list<T>`` argument.

  `#1249 <https://github.com/pybind/pybind11/pull/1249>`_.

* Fixed an issue where calling a function with a keep_alive policy on the same

  nurse/patient pair would cause the internal patient storage to needlessly

  grow (unboundedly, if the nurse is long-lived).

  `#1251 <https://github.com/pybind/pybind11/issues/1251>`_.

* Various other minor fixes.

v2.2.1 (September 14, 2017)

-----------------------------------------------------

* Added ``py::module::reload()`` member function for reloading a module.

  `#1040 <https://github.com/pybind/pybind11/pull/1040>`_.

* Fixed a reference leak in the number converter.

  `#1078 <https://github.com/pybind/pybind11/pull/1078>`_.

* Fixed compilation with Clang on host GCC < 5 (old libstdc++ which isn't fully

  C++11 compliant). `#1062 <https://github.com/pybind/pybind11/pull/1062>`_.

* Fixed a regression where the automatic ``std::vector<bool>`` caster would

  fail to compile. The same fix also applies to any container which returns

  element proxies instead of references.

  `#1053 <https://github.com/pybind/pybind11/pull/1053>`_.

* Fixed a regression where the ``py::keep_alive`` policy could not be applied

  to constructors. `#1065 <https://github.com/pybind/pybind11/pull/1065>`_.

* Fixed a nullptr dereference when loading a ``py::module_local`` type

  that's only registered in an external module.

  `#1058 <https://github.com/pybind/pybind11/pull/1058>`_.

* Fixed implicit conversion of accessors to types derived from ``py::object``.

  `#1076 <https://github.com/pybind/pybind11/pull/1076>`_.

* The ``name`` in ``PYBIND11_MODULE(name, variable)`` can now be a macro.

  `#1082 <https://github.com/pybind/pybind11/pull/1082>`_.

* Relaxed overly strict ``py::pickle()`` check for matching get and set types.

  `#1064 <https://github.com/pybind/pybind11/pull/1064>`_.

* Conversion errors now try to be more informative when it's likely that

  a missing header is the cause (e.g. forgetting ``<pybind11/stl.h>``).

  `#1077 <https://github.com/pybind/pybind11/pull/1077>`_.

v2.2.0 (August 31, 2017)

-----------------------------------------------------

* Support for embedding the Python interpreter. See the

  :doc:`documentation page </advanced/embedding>` for a

  full overview of the new features.

  `#774 <https://github.com/pybind/pybind11/pull/774>`_,

  `#889 <https://github.com/pybind/pybind11/pull/889>`_,

  `#892 <https://github.com/pybind/pybind11/pull/892>`_,

  `#920 <https://github.com/pybind/pybind11/pull/920>`_.

  .. code-block:: cpp

      #include <pybind11/embed.h>

      namespace py = pybind11;

      int main() {

          py::scoped_interpreter guard{}; // start the interpreter and keep it alive

          py::print("Hello, World!"); // use the Python API

      }

* Support for inheriting from multiple C++ bases in Python.

  `#693 <https://github.com/pybind/pybind11/pull/693>`_.

  .. code-block:: python

      from cpp_module import CppBase1, CppBase2

      class PyDerived(CppBase1, CppBase2):

          def __init__(self):

              CppBase1.__init__(self)  # C++ bases must be initialized explicitly

              CppBase2.__init__(self)

* ``PYBIND11_MODULE`` is now the preferred way to create module entry points.

  ``PYBIND11_PLUGIN`` is deprecated. See :ref:`macros` for details.

  `#879 <https://github.com/pybind/pybind11/pull/879>`_.

  .. code-block:: cpp

      // new

      PYBIND11_MODULE(example, m) {

          m.def("add", [](int a, int b) { return a + b; });

      }

      // old

      PYBIND11_PLUGIN(example) {

          py::module m("example");

          m.def("add", [](int a, int b) { return a + b; });

          return m.ptr();

      }

* pybind11's headers and build system now more strictly enforce hidden symbol

  visibility for extension modules. This should be seamless for most users,

  but see the :doc:`upgrade` if you use a custom build system.

  `#995 <https://github.com/pybind/pybind11/pull/995>`_.

* Support for ``py::module_local`` types which allow multiple modules to

  export the same C++ types without conflicts. This is useful for opaque

  types like ``std::vector<int>``. ``py::bind_vector`` and ``py::bind_map``

  now default to ``py::module_local`` if their elements are builtins or

  local types. See :ref:`module_local` for details.

  `#949 <https://github.com/pybind/pybind11/pull/949>`_,

  `#981 <https://github.com/pybind/pybind11/pull/981>`_,

  `#995 <https://github.com/pybind/pybind11/pull/995>`_,

  `#997 <https://github.com/pybind/pybind11/pull/997>`_.

* Custom constructors can now be added very easily using lambdas or factory

  functions which return a class instance by value, pointer or holder. This

  supersedes the old placement-new ``__init__`` technique.

  See :ref:`custom_constructors` for details.

  `#805 <https://github.com/pybind/pybind11/pull/805>`_,

  `#1014 <https://github.com/pybind/pybind11/pull/1014>`_.

  .. code-block:: cpp

      struct Example {

          Example(std::string);

      };

      py::class_<Example>(m, "Example")

          .def(py::init<std::string>()) // existing constructor

          .def(py::init([](int n) { // custom constructor

              return std::make_unique<Example>(std::to_string(n));

          }));

* Similarly to custom constructors, pickling support functions are now bound

  using the ``py::pickle()`` adaptor which improves type safety. See the

  :doc:`upgrade` and :ref:`pickling` for details.

  `#1038 <https://github.com/pybind/pybind11/pull/1038>`_.

* Builtin support for converting C++17 standard library types and general

  conversion improvements:

  1. C++17 ``std::variant`` is supported right out of the box. C++11/14

     equivalents (e.g. ``boost::variant``) can also be added with a simple

     user-defined specialization. See :ref:`cpp17_container_casters` for details.

     `#811 <https://github.com/pybind/pybind11/pull/811>`_,

     `#845 <https://github.com/pybind/pybind11/pull/845>`_,

     `#989 <https://github.com/pybind/pybind11/pull/989>`_.

  2. Out-of-the-box support for C++17 ``std::string_view``.

     `#906 <https://github.com/pybind/pybind11/pull/906>`_.

  3. Improved compatibility of the builtin ``optional`` converter.

     `#874 <https://github.com/pybind/pybind11/pull/874>`_.

  4. The ``bool`` converter now accepts ``numpy.bool_`` and types which

     define ``__bool__`` (Python 3.x) or ``__nonzero__`` (Python 2.7).

     `#925 <https://github.com/pybind/pybind11/pull/925>`_.

  5. C++-to-Python casters are now more efficient and move elements out

     of rvalue containers whenever possible.

     `#851 <https://github.com/pybind/pybind11/pull/851>`_,

     `#936 <https://github.com/pybind/pybind11/pull/936>`_,

     `#938 <https://github.com/pybind/pybind11/pull/938>`_.

  6. Fixed ``bytes`` to ``std::string/char*`` conversion on Python 3.

     `#817 <https://github.com/pybind/pybind11/pull/817>`_.

  7. Fixed lifetime of temporary C++ objects created in Python-to-C++ conversions.

     `#924 <https://github.com/pybind/pybind11/pull/924>`_.

* Scope guard call policy for RAII types, e.g. ``py::call_guard<py::gil_scoped_release>()``,

  ``py::call_guard<py::scoped_ostream_redirect>()``. See :ref:`call_policies` for details.

  `#740 <https://github.com/pybind/pybind11/pull/740>`_.

* Utility for redirecting C++ streams to Python (e.g. ``std::cout`` ->

  ``sys.stdout``). Scope guard ``py::scoped_ostream_redirect`` in C++ and

  a context manager in Python. See :ref:`ostream_redirect`.

  `#1009 <https://github.com/pybind/pybind11/pull/1009>`_.

* Improved handling of types and exceptions across module boundaries.

  `#915 <https://github.com/pybind/pybind11/pull/915>`_,

  `#951 <https://github.com/pybind/pybind11/pull/951>`_,

  `#995 <https://github.com/pybind/pybind11/pull/995>`_.

* Fixed destruction order of ``py::keep_alive`` nurse/patient objects

  in reference cycles.

  `#856 <https://github.com/pybind/pybind11/pull/856>`_.

* Numpy and buffer protocol related improvements:

  1. Support for negative strides in Python buffer objects/numpy arrays. This

     required changing integers from unsigned to signed for the related C++ APIs.

     Note: If you have compiler warnings enabled, you may notice some new conversion

     warnings after upgrading. These can be resolved with ``static_cast``.

     `#782 <https://github.com/pybind/pybind11/pull/782>`_.

  2. Support ``std::complex`` and arrays inside ``PYBIND11_NUMPY_DTYPE``.

     `#831 <https://github.com/pybind/pybind11/pull/831>`_,

     `#832 <https://github.com/pybind/pybind11/pull/832>`_.

  3. Support for constructing ``py::buffer_info`` and ``py::arrays`` using

     arbitrary containers or iterators instead of requiring a ``std::vector``.

     `#788 <https://github.com/pybind/pybind11/pull/788>`_,

     `#822 <https://github.com/pybind/pybind11/pull/822>`_,

     `#860 <https://github.com/pybind/pybind11/pull/860>`_.

  4. Explicitly check numpy version and require >= 1.7.0.

     `#819 <https://github.com/pybind/pybind11/pull/819>`_.

* Support for allowing/prohibiting ``None`` for specific arguments and improved

  ``None`` overload resolution order. See :ref:`none_arguments` for details.

  `#843 <https://github.com/pybind/pybind11/pull/843>`_.

  `#859 <https://github.com/pybind/pybind11/pull/859>`_.

* Added ``py::exec()`` as a shortcut for ``py::eval<py::eval_statements>()``

  and support for C++11 raw string literals as input. See :ref:`eval`.

  `#766 <https://github.com/pybind/pybind11/pull/766>`_,

  `#827 <https://github.com/pybind/pybind11/pull/827>`_.

* ``py::vectorize()`` ignores non-vectorizable arguments and supports

  member functions.

  `#762 <https://github.com/pybind/pybind11/pull/762>`_.

* Support for bound methods as callbacks (``pybind11/functional.h``).

  `#815 <https://github.com/pybind/pybind11/pull/815>`_.

* Allow aliasing pybind11 methods: ``cls.attr("foo") = cls.attr("bar")``.

  `#802 <https://github.com/pybind/pybind11/pull/802>`_.

* Don't allow mixed static/non-static overloads.

  `#804 <https://github.com/pybind/pybind11/pull/804>`_.

* Fixed overriding static properties in derived classes.

  `#784 <https://github.com/pybind/pybind11/pull/784>`_.

* Added support for write only properties.

  `#1144 <https://github.com/pybind/pybind11/pull/1144>`_.

* Improved deduction of member functions of a derived class when its bases

  aren't registered with pybind11.

  `#855 <https://github.com/pybind/pybind11/pull/855>`_.

  .. code-block:: cpp

      struct Base {

          int foo() { return 42; }

      }

      struct Derived : Base {}

      // Now works, but previously required also binding `Base`

      py::class_<Derived>(m, "Derived")

          .def("foo", &Derived::foo); // function is actually from `Base`

* The implementation of ``py::init<>`` now uses C++11 brace initialization

  syntax to construct instances, which permits binding implicit constructors of

  aggregate types. `#1015 <https://github.com/pybind/pybind11/pull/1015>`_.

    .. code-block:: cpp

        struct Aggregate {

            int a;

            std::string b;

        };

        py::class_<Aggregate>(m, "Aggregate")

            .def(py::init<int, const std::string &>());

* Fixed issues with multiple inheritance with offset base/derived pointers.

  `#812 <https://github.com/pybind/pybind11/pull/812>`_,

  `#866 <https://github.com/pybind/pybind11/pull/866>`_,

  `#960 <https://github.com/pybind/pybind11/pull/960>`_.

* Fixed reference leak of type objects.

  `#1030 <https://github.com/pybind/pybind11/pull/1030>`_.

* Improved support for the ``/std:c++14`` and ``/std:c++latest`` modes

  on MSVC 2017.

  `#841 <https://github.com/pybind/pybind11/pull/841>`_,

  `#999 <https://github.com/pybind/pybind11/pull/999>`_.

* Fixed detection of private operator new on MSVC.

  `#893 <https://github.com/pybind/pybind11/pull/893>`_,

  `#918 <https://github.com/pybind/pybind11/pull/918>`_.

* Intel C++ compiler compatibility fixes.

  `#937 <https://github.com/pybind/pybind11/pull/937>`_.

* Fixed implicit conversion of `py::enum_` to integer types on Python 2.7.

  `#821 <https://github.com/pybind/pybind11/pull/821>`_.

* Added ``py::hash`` to fetch the hash value of Python objects, and

  ``.def(hash(py::self))`` to provide the C++ ``std::hash`` as the Python

  ``__hash__`` method.

  `#1034 <https://github.com/pybind/pybind11/pull/1034>`_.

* Fixed ``__truediv__`` on Python 2 and ``__itruediv__`` on Python 3.

  `#867 <https://github.com/pybind/pybind11/pull/867>`_.

* ``py::capsule`` objects now support the ``name`` attribute. This is useful

  for interfacing with ``scipy.LowLevelCallable``.

  `#902 <https://github.com/pybind/pybind11/pull/902>`_.

* Fixed ``py::make_iterator``'s ``__next__()`` for past-the-end calls.

  `#897 <https://github.com/pybind/pybind11/pull/897>`_.

* Added ``error_already_set::matches()`` for checking Python exceptions.

  `#772 <https://github.com/pybind/pybind11/pull/772>`_.

* Deprecated ``py::error_already_set::clear()``. It's no longer needed

  following a simplification of the ``py::error_already_set`` class.

  `#954 <https://github.com/pybind/pybind11/pull/954>`_.

* Deprecated ``py::handle::operator==()`` in favor of ``py::handle::is()``

  `#825 <https://github.com/pybind/pybind11/pull/825>`_.

* Deprecated ``py::object::borrowed``/``py::object::stolen``.

  Use ``py::object::borrowed_t{}``/``py::object::stolen_t{}`` instead.

  `#771 <https://github.com/pybind/pybind11/pull/771>`_.

* Changed internal data structure versioning to avoid conflicts between

  modules compiled with different revisions of pybind11.

  `#1012 <https://github.com/pybind/pybind11/pull/1012>`_.

* Additional compile-time and run-time error checking and more informative messages.

  `#786 <https://github.com/pybind/pybind11/pull/786>`_,

  `#794 <https://github.com/pybind/pybind11/pull/794>`_,

  `#803 <https://github.com/pybind/pybind11/pull/803>`_.

* Various minor improvements and fixes.

  `#764 <https://github.com/pybind/pybind11/pull/764>`_,

  `#791 <https://github.com/pybind/pybind11/pull/791>`_,

  `#795 <https://github.com/pybind/pybind11/pull/795>`_,

  `#840 <https://github.com/pybind/pybind11/pull/840>`_,

  `#844 <https://github.com/pybind/pybind11/pull/844>`_,

  `#846 <https://github.com/pybind/pybind11/pull/846>`_,

  `#849 <https://github.com/pybind/pybind11/pull/849>`_,

  `#858 <https://github.com/pybind/pybind11/pull/858>`_,

  `#862 <https://github.com/pybind/pybind11/pull/862>`_,

  `#871 <https://github.com/pybind/pybind11/pull/871>`_,

  `#872 <https://github.com/pybind/pybind11/pull/872>`_,

  `#881 <https://github.com/pybind/pybind11/pull/881>`_,

  `#888 <https://github.com/pybind/pybind11/pull/888>`_,

  `#899 <https://github.com/pybind/pybind11/pull/899>`_,

  `#928 <https://github.com/pybind/pybind11/pull/928>`_,

  `#931 <https://github.com/pybind/pybind11/pull/931>`_,

  `#944 <https://github.com/pybind/pybind11/pull/944>`_,

  `#950 <https://github.com/pybind/pybind11/pull/950>`_,

  `#952 <https://github.com/pybind/pybind11/pull/952>`_,

  `#962 <https://github.com/pybind/pybind11/pull/962>`_,

  `#965 <https://github.com/pybind/pybind11/pull/965>`_,

  `#970 <https://github.com/pybind/pybind11/pull/970>`_,

  `#978 <https://github.com/pybind/pybind11/pull/978>`_,

  `#979 <https://github.com/pybind/pybind11/pull/979>`_,

  `#986 <https://github.com/pybind/pybind11/pull/986>`_,

  `#1020 <https://github.com/pybind/pybind11/pull/1020>`_,

  `#1027 <https://github.com/pybind/pybind11/pull/1027>`_,

  `#1037 <https://github.com/pybind/pybind11/pull/1037>`_.

* Testing improvements.

  `#798 <https://github.com/pybind/pybind11/pull/798>`_,

  `#882 <https://github.com/pybind/pybind11/pull/882>`_,

  `#898 <https://github.com/pybind/pybind11/pull/898>`_,

  `#900 <https://github.com/pybind/pybind11/pull/900>`_,

  `#921 <https://github.com/pybind/pybind11/pull/921>`_,

  `#923 <https://github.com/pybind/pybind11/pull/923>`_,

  `#963 <https://github.com/pybind/pybind11/pull/963>`_.

v2.1.1 (April 7, 2017)

-----------------------------------------------------

* Fixed minimum version requirement for MSVC 2015u3

  `#773 <https://github.com/pybind/pybind11/pull/773>`_.

v2.1.0 (March 22, 2017)

-----------------------------------------------------

* pybind11 now performs function overload resolution in two phases. The first

  phase only considers exact type matches, while the second allows for implicit

  conversions to take place. A special ``noconvert()`` syntax can be used to

  completely disable implicit conversions for specific arguments.

  `#643 <https://github.com/pybind/pybind11/pull/643>`_,

  `#634 <https://github.com/pybind/pybind11/pull/634>`_,

  `#650 <https://github.com/pybind/pybind11/pull/650>`_.

* Fixed a regression where static properties no longer worked with classes

  using multiple inheritance. The ``py::metaclass`` attribute is no longer

  necessary (and deprecated as of this release) when binding classes with

  static properties.

  `#679 <https://github.com/pybind/pybind11/pull/679>`_,

* Classes bound using ``pybind11`` can now use custom metaclasses.

  `#679 <https://github.com/pybind/pybind11/pull/679>`_,

* ``py::args`` and ``py::kwargs`` can now be mixed with other positional

  arguments when binding functions using pybind11.

  `#611 <https://github.com/pybind/pybind11/pull/611>`_.

* Improved support for C++11 unicode string and character types; added

  extensive documentation regarding pybind11's string conversion behavior.

  `#624 <https://github.com/pybind/pybind11/pull/624>`_,

  `#636 <https://github.com/pybind/pybind11/pull/636>`_,

  `#715 <https://github.com/pybind/pybind11/pull/715>`_.

* pybind11 can now avoid expensive copies when converting Eigen arrays to NumPy

  arrays (and vice versa). `#610 <https://github.com/pybind/pybind11/pull/610>`_.

* The "fast path" in ``py::vectorize`` now works for any full-size group of C or

  F-contiguous arrays. The non-fast path is also faster since it no longer performs

  copies of the input arguments (except when type conversions are necessary).

  `#610 <https://github.com/pybind/pybind11/pull/610>`_.

* Added fast, unchecked access to NumPy arrays via a proxy object.

  `#746 <https://github.com/pybind/pybind11/pull/746>`_.

* Transparent support for class-specific ``operator new`` and

  ``operator delete`` implementations.

  `#755 <https://github.com/pybind/pybind11/pull/755>`_.

* Slimmer and more efficient STL-compatible iterator interface for sequence types.

  `#662 <https://github.com/pybind/pybind11/pull/662>`_.

* Improved custom holder type support.

  `#607 <https://github.com/pybind/pybind11/pull/607>`_.

* ``nullptr`` to ``None`` conversion fixed in various builtin type casters.

  `#732 <https://github.com/pybind/pybind11/pull/732>`_.

* ``enum_`` now exposes its members via a special ``__members__`` attribute.

  `#666 <https://github.com/pybind/pybind11/pull/666>`_.

* ``std::vector`` bindings created using ``stl_bind.h`` can now optionally

  implement the buffer protocol. `#488 <https://github.com/pybind/pybind11/pull/488>`_.

* Automated C++ reference documentation using doxygen and breathe.

  `#598 <https://github.com/pybind/pybind11/pull/598>`_.

* Added minimum compiler version assertions.

  `#727 <https://github.com/pybind/pybind11/pull/727>`_.

* Improved compatibility with C++1z.

  `#677 <https://github.com/pybind/pybind11/pull/677>`_.

* Improved ``py::capsule`` API. Can be used to implement cleanup

  callbacks that are involved at module destruction time.

  `#752 <https://github.com/pybind/pybind11/pull/752>`_.

* Various minor improvements and fixes.

  `#595 <https://github.com/pybind/pybind11/pull/595>`_,

  `#588 <https://github.com/pybind/pybind11/pull/588>`_,

  `#589 <https://github.com/pybind/pybind11/pull/589>`_,

  `#603 <https://github.com/pybind/pybind11/pull/603>`_,

  `#619 <https://github.com/pybind/pybind11/pull/619>`_,

  `#648 <https://github.com/pybind/pybind11/pull/648>`_,

  `#695 <https://github.com/pybind/pybind11/pull/695>`_,

  `#720 <https://github.com/pybind/pybind11/pull/720>`_,

  `#723 <https://github.com/pybind/pybind11/pull/723>`_,

  `#729 <https://github.com/pybind/pybind11/pull/729>`_,

  `#724 <https://github.com/pybind/pybind11/pull/724>`_,

  `#742 <https://github.com/pybind/pybind11/pull/742>`_,

  `#753 <https://github.com/pybind/pybind11/pull/753>`_.

v2.0.1 (Jan 4, 2017)

-----------------------------------------------------

* Fix pointer to reference error in type_caster on MSVC

  `#583 <https://github.com/pybind/pybind11/pull/583>`_.

* Fixed a segmentation in the test suite due to a typo

  `cd7eac <https://github.com/pybind/pybind11/commit/cd7eac>`_.

v2.0.0 (Jan 1, 2017)

-----------------------------------------------------

* Fixed a reference counting regression affecting types with custom metaclasses

  (introduced in v2.0.0-rc1).

  `#571 <https://github.com/pybind/pybind11/pull/571>`_.

* Quenched a CMake policy warning.

  `#570 <https://github.com/pybind/pybind11/pull/570>`_.

v2.0.0-rc1 (Dec 23, 2016)

-----------------------------------------------------

The pybind11 developers are excited to issue a release candidate of pybind11

with a subsequent v2.0.0 release planned in early January next year.

An incredible amount of effort by went into pybind11 over the last ~5 months,

leading to a release that is jam-packed with exciting new features and numerous

usability improvements. The following list links PRs or individual commits

whenever applicable.

Happy Christmas!

* Support for binding C++ class hierarchies that make use of multiple

  inheritance. `#410 <https://github.com/pybind/pybind11/pull/410>`_.

* PyPy support: pybind11 now supports nightly builds of PyPy and will

  interoperate with the future 5.7 release. No code changes are necessary,

  everything "just" works as usual. Note that we only target the Python 2.7

  branch for now; support for 3.x will be added once its ``cpyext`` extension

  support catches up. A few minor features remain unsupported for the time

  being (notably dynamic attributes in custom types).

  `#527 <https://github.com/pybind/pybind11/pull/527>`_.

* Significant work on the documentation -- in particular, the monolithic

  ``advanced.rst`` file was restructured into a easier to read hierarchical

  organization. `#448 <https://github.com/pybind/pybind11/pull/448>`_.

* Many NumPy-related improvements:

  1. Object-oriented API to access and modify NumPy ``ndarray`` instances,

     replicating much of the corresponding NumPy C API functionality.

     `#402 <https://github.com/pybind/pybind11/pull/402>`_.

  2. NumPy array ``dtype`` array descriptors are now first-class citizens and

     are exposed via a new class ``py::dtype``.

  3. Structured dtypes can be registered using the ``PYBIND11_NUMPY_DTYPE()``

     macro. Special ``array`` constructors accepting dtype objects were also

     added.

     One potential caveat involving this change: format descriptor strings

     should now be accessed via ``format_descriptor::format()`` (however, for

     compatibility purposes, the old syntax ``format_descriptor::value`` will

     still work for non-structured data types). `#308

     <https://github.com/pybind/pybind11/pull/308>`_.

  4. Further improvements to support structured dtypes throughout the system.

     `#472 <https://github.com/pybind/pybind11/pull/472>`_,

     `#474 <https://github.com/pybind/pybind11/pull/474>`_,

     `#459 <https://github.com/pybind/pybind11/pull/459>`_,

     `#453 <https://github.com/pybind/pybind11/pull/453>`_,

     `#452 <https://github.com/pybind/pybind11/pull/452>`_, and

     `#505 <https://github.com/pybind/pybind11/pull/505>`_.

  5. Fast access operators. `#497 <https://github.com/pybind/pybind11/pull/497>`_.

  6. Constructors for arrays whose storage is owned by another object.

     `#440 <https://github.com/pybind/pybind11/pull/440>`_.

  7. Added constructors for ``array`` and ``array_t`` explicitly accepting shape

     and strides; if strides are not provided, they are deduced assuming

     C-contiguity. Also added simplified constructors for 1-dimensional case.

  8. Added buffer/NumPy support for ``char[N]`` and ``std::array<char, N>`` types.

  9. Added ``memoryview`` wrapper type which is constructible from ``buffer_info``.

* Eigen: many additional conversions and support for non-contiguous

  arrays/slices.

  `#427 <https://github.com/pybind/pybind11/pull/427>`_,

  `#315 <https://github.com/pybind/pybind11/pull/315>`_,

  `#316 <https://github.com/pybind/pybind11/pull/316>`_,

  `#312 <https://github.com/pybind/pybind11/pull/312>`_, and

  `#267 <https://github.com/pybind/pybind11/pull/267>`_

* Incompatible changes in ``class_<...>::class_()``:

    1. Declarations of types that provide access via the buffer protocol must

       now include the ``py::buffer_protocol()`` annotation as an argument to

       the ``class_`` constructor.

    2. Declarations of types that require a custom metaclass (i.e. all classes

       which include static properties via commands such as

       ``def_readwrite_static()``) must now include the ``py::metaclass()``

       annotation as an argument to the ``class_`` constructor.

       These two changes were necessary to make type definitions in pybind11

       future-proof, and to support PyPy via its cpyext mechanism. `#527

       <https://github.com/pybind/pybind11/pull/527>`_.

    3. This version of pybind11 uses a redesigned mechanism for instantiating