Update to 0.20:

0.20 (??)
===================

Features added
--------------

* Support for CPython 3.4.

* Support for calling C++ template functions.

* ``yield`` is supported in ``finally`` clauses.

* The C code generated for finally blocks is duplicated for each exit
  case to allow for better optimisations by the C compiler.

* Cython tries to undo the Python optimisationism of assigning a bound
  method to a local variable when it can generate better code for the
  direct call.

* Constant Python float values are cached.

* String equality comparisons can use faster type specific code in
  more cases than before.

* String/Unicode formatting using the '%' operator uses a faster
  C-API call.

* ``bytearray`` has become a known type and supports coercion from and
  to C strings.  Indexing, slicing and decoding is optimised. Note that
  this may have an impact on existing code due to type inference.

* Using ``cdef basestring stringvar`` and function arguments typed as
  ``basestring`` is now meaningful and allows assigning exactly
  ``str`` and ``unicode`` objects, but no subtypes of these types.

* Support for the ``__debug__`` builtin.

* Assertions in Cython compiled modules are disabled if the running
  Python interpreter was started with the "-O" option.

* Some types that Cython provides internally, such as functions and
  generators, are now shared across modules if more than one Cython
  implemented module is imported.

* The type inference algorithm works more fine granular by taking the
  results of the control flow analysis into account.

* A new script in ``bin/cythonize`` provides a command line frontend
  to the cythonize() compilation function (including distutils build).

* The new extension type decorator ``@cython.no_gc_clear`` prevents
  objects from being cleared during cyclic garbage collection, thus
  making sure that object attributes are kept alive until deallocation.

* During cyclic garbage collection, attributes of extension types that
  cannot create reference cycles due to their type (e.g. strings) are
  no longer considered for traversal or clearing.  This can reduce the
  processing overhead when searching for or cleaning up reference cycles.

* Package compilation (i.e. ``__init__.py`` files) now works, starting
  with Python 3.3.

* The cython-mode.el script for Emacs was updated.  Patch by Ivan Andrus.

* An option common_utility_include_dir was added to cythonize() to save
  oft-used utility code once in a separate directory rather than as
  part of each generated file.

* ``unraisable_tracebacks`` directive added to control printing of
  tracebacks of unraisable exceptions.

Bugs fixed
----------

* Abstract Python classes that subtyped a Cython extension type
  failed to raise an exception on instantiation, and thus ended
  up being instantiated.

* ``set.add(a_tuple)`` and ``set.discard(a_tuple)`` failed with a
  TypeError in Py2.4.

* The PEP 3155 ``__qualname__`` was incorrect for nested classes and
  inner classes/functions declared as ``global``.

* Several corner cases in the try-finally statement were fixed.

* The metaclass of a Python class was not inherited from its parent
  class(es).  It is now extracted from the list of base classes if not
  provided explicitly using the Py3 ``metaclass`` keyword argument.
  In Py2 compilation mode, a ``__metaclass__`` entry in the class
  dict will still take precedence if not using Py3 metaclass syntax,
  but only *after* creating the class dict (which may have been done
  by a metaclass of a base class, see PEP 3115).  It is generally
  recommended to use the explicit Py3 syntax to define metaclasses
  for Python types at compile time.

* The automatic C switch statement generation behaves more safely for
  heterogeneous value types (e.g. mixing enum and char), allowing for
  a slightly wider application and reducing corner cases.  It now always
  generates a 'default' clause to avoid C compiler warnings about
  unmatched enum values.

* Fixed a bug where class hierarchies declared out-of-order could result
  in broken generated code.

* Fixed a bug which prevented overriding const methods of C++ classes.

* Fixed a crash when converting Python objects to C++ strings fails.

Other changes
-------------

* In Py3 compilation mode, Python2-style metaclasses declared by a
  ``__metaclass__`` class dict entry are ignored.

* In Py3.4+, the Cython generator type uses ``tp_finalize()`` for safer
  cleanup instead of ``tp_del()``.


(wiz)