Cython

===================

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

* Crash when assigning a C value to both a Python and C target at the same time.

* Automatic coercion from C++ strings to ``str`` generated incomplete code that
failed to compile.

* Declaring a constructor in a C++ child class erroneously required a default
constructor declaration in the super class.

* ``resize_smart()`` in ``cpython.array`` was broken.

* Functions in ``libcpp.cast`` are now declared as ``nogil``.

* Some missing C-API declarations were added.

* Py3 main code in embedding program code was lacking casts.

* Exception related to distutils "Distribution" class type in pyximport under
latest CPython 2.7 and 3.4 releases when setuptools is being imported later.

===================

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

* New ``cythonize`` option ``-a`` to generate the annotated HTML source view.

* Missing C-API declarations in ``cpython.unicode`` were added.

* Passing ``language='c++'`` into cythonize() globally enables C++ mode for
all modules that were not passed as Extension objects (i.e. only source
files and file patterns).

* ``Py_hash_t`` is a known type (used in CPython for hash values).

* ``PySlice_*()`` C-API functions are available from the ``cpython.slice``
module.

* Allow arrays of C++ classes.

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

* Reference leak for non-simple Python expressions in boolean and/or expressions.

* To fix a name collision and to reflect availability on host platforms,
standard C declarations [ clock(), time(), struct tm and tm* functions ]
were moved from posix/time.pxd to a new libc/time.pxd. Patch by Charles
Blake.

* Rerunning unmodified modules in IPython's cython support failed.
Patch by Matthias Bussonier.

* Casting C++ ``std::string`` to Python byte strings failed when
auto-decoding was enabled.

* Fatal exceptions in global module init code could lead to crashes
if the already created module was used later on (e.g. through a
stale reference in sys.modules or elsewhere).

* ``cythonize.py`` script was not installed on MS-Windows.

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

* Compilation no longer fails hard when unknown compilation options are
passed. Instead, it raises a warning and ignores them (as it did silently
before 0.21). This will be changed back to an error in a future release.

=================

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

* C (cdef) functions allow inner Python functions.

* Enums can now be declared as cpdef to export their values to
the module's Python namespace. Cpdef enums in pxd files export
their values to their own module, iff it exists.

* Allow staticmethod decorator to declare static cdef methods.
This is especially useful for declaring "constructors" for
cdef classes that can take non-Python arguments.

* Taking a ``char*`` from a temporary Python string object is safer
in more cases and can be done inside of non-trivial expressions,
including arguments of a function call. A compile time error
is raised only when such a pointer is assigned to a variable and
would thus exceed the lifetime of the string itself.

* Generators have new properties ``__name__`` and ``__qualname__``
that provide the plain/qualified name of the generator function
(following CPython 3.5). See https://bugs.python.org/issue21205

* The ``inline`` function modifier is available as a decorator
``cython.inline`` in pure mode.

* When cygdb is run in a virtualenv, it enables the same virtualenv
inside of the debugger. Patch by Marc Abramowitz.

* PEP 465: dedicated infix operator for matrix multiplication (A B).

* HTML output of annotated code uses Pygments for code highlighting
and generally received a major overhaul by Matthias Bussonier.

* IPython magic support is now available directly from Cython with
the command "%load_ext cython". Cython code can directly be
executed in a cell when marked with "%%cython". Code analysis
is available with "%%cython -a". Patch by Martín Gaitán.

* Simple support for declaring Python object types in Python signature
annotations. Currently requires setting the compiler directive
``annotation_typing=True``.

* New directive ``use_switch`` (defaults to True) to optionally disable
the optimization of chained if statement to C switch statements.

* Defines dynamic_cast et al. in ``libcpp.cast`` and C++ heap data
structure operations in ``libcpp.algorithm``.

* Shipped header declarations in ``posix.*`` were extended to cover
more of the POSIX API. Patches by Lars Buitinck and Mark Peek.

Optimizations
-------------

* Simple calls to C implemented Python functions/methods are faster.
This also speeds up many operations on builtins that Cython cannot
otherwise optimise.

* The "and"/"or" operators try to avoid unnecessary coercions of their
arguments. They now evaluate the truth value of each argument
independently and only coerce the final result of the whole expression
to the target type (e.g. the type on the left side of an assignment).
This also avoids reference counting overhead for Python values during
evaluation and generally improves the code flow in the generated C code.

* The Python expression "2 ** N" is optimised into bit shifting.
See https://bugs.python.org/issue21420

* Cascaded assignments (a = b = ...) try to minimise the number of
type coercions.

* Calls to ``slice()`` are translated to a straight C-API call.

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

* Crash when assigning memory views from ternary conditional expressions.

* Nested C++ templates could lead to unseparated ">>" characters being
generated into the C++ declarations, which older C++ compilers could
not parse.

* Sending SIGINT (Ctrl-C) during parallel cythonize() builds could
hang the child processes.

* No longer ignore local setup.cfg files for distutils in pyximport.
Patch by Martin Teichmann.

* Taking a ``char*`` from an indexed Python string generated unsafe
reference counting code.

* Set literals now create all of their items before trying to add them
to the set, following the behaviour in CPython. This makes a
difference in the rare case that the item creation has side effects
and some items are not hashable (or if hashing them has side effects,
too).

* Cython no longer generates the cross product of C functions for code
that uses memory views of fused types in function signatures (e.g.
``cdef func(floating[:] a, floating[:] b)``). This is considered the
expected behaviour by most users and was previously inconsistent with
other structured types like C arrays. Code that really wants all type
combinations can create the same fused memoryview type under different
names and use those in the signature to make it clear which types are
independent.

* Names that were unknown at compile time were looked up as builtins at
runtime but not as global module names. Trying both lookups helps with
globals() manipulation.

* Fixed stl container conversion for typedef element types.

* ``obj.pop(x)`` truncated large C integer values of x to ``Py_ssize_t``.

* ``__init__.pyc`` is recognised as marking a package directory
(in addition to .py, .pyx and .pxd).

* Syntax highlighting in ``cython-mode.el`` for Emacs no longer
incorrectly highlights keywords found as part of longer names.

* Correctly handle ``from cython.submodule cimport name``.

* Fix infinite recursion when using super with cpdef methods.

* No-args ``dir()`` was not guaranteed to return a sorted list.

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

* The header line in the generated C files no longer contains the
timestamp but only the Cython version that wrote it. This was
changed to make builds more reproducible.

* Removed support for CPython 2.4, 2.5 and 3.1.

* The licensing implications on the generated code were clarified
to avoid legal constraints for users.

===================

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

* Some optimisations for set/frozenset instantiation.

* Support for C++ unordered_set and unordered_map.

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

* Access to attributes of optimised builtin methods (e.g.
``[].append.__name__``) could fail to compile.

* Memory leak when extension subtypes add a memory view as attribute
to those of the parent type without having Python object attributes
or a user provided dealloc method.

* Compiler crash on readonly properties in "binding" mode.

* Auto-encoding with ``c_string_encoding=ascii`` failed in Py3.3.

* Crash when subtyping freelist enabled Cython extension types with
Python classes that use ``__slots__``.

* Freelist usage is restricted to CPython to avoid problems with other
Python implementations.

* Memory leak in memory views when copying overlapping, contiguous slices.

* Format checking when requesting non-contiguous buffers from
``cython.array`` objects was accidentally omitted in Py3.

* C++ destructor calls in extension types could fail to compile in clang.

* Buffer format validation failed for sequences of strings in structs.

* Docstrings on extension type attributes in .pxd files were rejected.

===================

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

* Build error under recent MacOS-X versions where ``isspace()`` could not be
resolved by clang.

* List/Tuple literals multiplied by more than one factor were only multiplied
by the last factor instead of all.

* Lookups of special methods (specifically for context managers) could fail
in Python <= 2.6/3.1.

* Local variables were erroneously appended to the signature introspection
of Cython implemented functions with keyword-only arguments under Python 3.

* In-place assignments to variables with inferred Python builtin/extension
types could fail with type errors if the result value type was incompatible
with the type of the previous value.

* The C code generation order of cdef classes, closures, helper code,
etc. was not deterministic, thus leading to high code churn.

* Type inference could fail to deduce C enum types.

* Type inference could deduce unsafe or inefficient types from integer
assignments within a mix of inferred Python variables and integer
variables.

=================

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()``.