Metadata-Version: 2.4
Name: Cython
Version: 3.3.0b1
Summary: The Cython compiler for writing C extensions in the Python language.
Home-page: https://cython.org/
Author: Robert Bradshaw, Stefan Behnel, David Woods, Greg Ewing, et al.
Author-email: cython-devel@python.org
License: Apache-2.0
Project-URL: Documentation, https://cython.readthedocs.io/
Project-URL: Donate, https://cython.readthedocs.io/en/latest/src/donating.html
Project-URL: Source Code, https://github.com/cython/cython
Project-URL: Bug Tracker, https://github.com/cython/cython/issues/
Project-URL: User Group, https://groups.google.com/g/cython-users
Classifier: Development Status :: 4 - Beta
Classifier: Intended Audience :: Developers
Classifier: Operating System :: OS Independent
Classifier: Programming Language :: Python
Classifier: Programming Language :: Python :: 3
Classifier: Programming Language :: Python :: 3.9
Classifier: Programming Language :: Python :: 3.10
Classifier: Programming Language :: Python :: 3.11
Classifier: Programming Language :: Python :: 3.12
Classifier: Programming Language :: Python :: 3.13
Classifier: Programming Language :: Python :: 3.14
Classifier: Programming Language :: Python :: Implementation :: CPython
Classifier: Programming Language :: Python :: Implementation :: PyPy
Classifier: Programming Language :: C
Classifier: Programming Language :: C++
Classifier: Programming Language :: Cython
Classifier: Topic :: Software Development :: Code Generators
Classifier: Topic :: Software Development :: Compilers
Classifier: Topic :: Software Development :: Libraries :: Python Modules
Classifier: Typing :: Typed
Requires-Python: >=3.9
Description-Content-Type: text/x-rst
Dynamic: author
Dynamic: author-email
Dynamic: classifier
Dynamic: description
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The Cython language makes writing C extensions for the Python language as
easy as Python itself.  Cython is a source code translator based on Pyrex_,
but supports more cutting edge functionality and optimizations.

The Cython language is a superset of the Python language (almost all Python
code is also valid Cython code), but Cython additionally supports optional
static typing to natively call C functions, operate with C++ classes and
declare fast C types on variables and class attributes.  This allows the
compiler to generate very efficient C code from Cython code.

This makes Cython the ideal language for writing glue code for external
C/C++ libraries, and for fast C modules that speed up the execution of
Python code.

The newest Cython release can always be downloaded from https://cython.org/.
Unpack the tarball or zip file, enter the directory, and then run::

    pip install .

Note that for one-time builds, e.g. for CI/testing, on platforms that are not
covered by one of the wheel packages provided on PyPI *and* the pure Python wheel
that we provide is not used, it is substantially faster than a full source build
to install an uncompiled (slower) version of Cython with::

    NO_CYTHON_COMPILE=true pip install .

.. _Pyrex: https://www.cosc.canterbury.ac.nz/greg.ewing/python/Pyrex/

3.3.0b1 (2026-08-14)
====================

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

* Cython now uses a new export/import naming scheme for fused C functions that
  increases the resilience against seemingly compatible user code changes.
  The original names are kept for backwards compatibility.
  (Github issue https://github.com/cython/cython/issues/7656)

* ``except *`` (PEP-654 exception groups) is implemented for Python 3.11 and later.
  (Github issue https://github.com/cython/cython/issues/4993)

* Unpacking in comprehensions (PEP-798) is implemented for list/set/dict comprehensions.
  It is not yet available for generator expressions.
  Original patch by Morax.  (Github issue https://github.com/cython/cython/issues/7898)

* The feature set of the shared module can be selected at build time
  by listing named features to include or exclude.
  This is an experimental configuration, subject to further improvements.
  Failures to include used features will currently result in import failures.
  (Github issue https://github.com/cython/cython/issues/7759)

* To control the generation of the shared module, the ``cython`` command gained
  a sub-command ``cython generate-shared pkg/modulename.c`` with additional options
  ``--only`` and ``--exclude``.
  Patch by Raza Khan.  (Github issue https://github.com/cython/cython/issues/7842)

* Exception base types are inferred for the target variable of multi-exception ``except``
  clauses and for collections of exceptions.  Properties like ``.args`` and ``.context``
  use direct C access in CPython.
  (Github issue https://github.com/cython/cython/issues/7783)

* Annotations on global variables are now used by type inference.
  (Github issue https://github.com/cython/cython/issues/7877)

* C property setters can now explicitly propagate exceptions, instead of always triggering
  a call to ``PyErr_Occurred()`` by returning ``void``.
  (Github issue https://github.com/cython/cython/issues/7791)

* Conditions in strongly predictable if-clauses or if-else expressions can be wrapped in
  ``cython.likely(condition)`` or ``cython.unlikely(condition)`` to help the C compiler
  optimise the branch.  Note that Cython automatically detects ``raise`` and ``assert``
  statements as terminators already and marks if-clauses that directly lead to them as
  ``unlikely()``, without user interaction.
  (Github issue https://github.com/cython/cython/issues/7667)

* The typed tuple syntax ``tuple[atype, ...]`` for homogeneous tuples is supported.
  (Github issue https://github.com/cython/cython/issues/7798)

* The return type inference for calls to builtin methods was improved, including dict views.
  (Github issues https://github.com/cython/cython/issues/7887, https://github.com/cython/cython/issues/7888)

* ``cython.py_int`` (and the same for ``py_float``, ``py_complex`` and ``py_bool``)
  can be used to refer to Python's builtin types in a C type context, e.g. after ``cdef``,
  where they are normally shadowed by the C types of the same name.
  (Github issue https://github.com/cython/cython/issues/7844)

* Constant ``frozenset`` objects are deduplicated and cached at module init time
  (similar to constant tuple and slice objects).
  Original Patch by Zhenbo Li. (Github issue https://github.com/cython/cython/issues/2741)

* Formatting C floating point values in f-strings is faster.
  Patch by Vladimir Saraikin.  (Github issue https://github.com/cython/cython/issues/7797)

* ``bytearray.extend(bytes)`` is faster.
  (Github issue https://github.com/cython/cython/issues/7797)

* Single character `in`-tests on ``str``, ``bytes`` and ``bytearray`` are optimised.
  (Github issue https://github.com/cython/cython/issues/3888)

* ``assert`` conditions are constant-folded.
  (Github issue https://github.com/cython/cython/issues/7797)

* Async generator objects are slightly smaller.
  (Github issue https://github.com/cython/cython/issues/7776)

* Two more Cython modules are compiled in the binary wheels, which should improve the
  translation speed for modules with many strings.
  (Github issue https://github.com/cython/cython/issues/7795)

* ``TreeFragment.parse_from_strings()`` now supports full modules and ``.pxd`` files.
  Patch by Itamar Turner-Trauring.  (Github issue https://github.com/cython/cython/issues/7827)

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

* Several issues with ``.close()`` or ``.throw()`` of Async generator asend/athrow
  objects were resolved, following fixes in CPython.
  (Github issue https://github.com/cython/cython/issues/7777)

* The ``__class__`` method cell misbehaved when used together with class decorators
  and passed the decorated class (and thus an arbitrary object) into ``super()``
  instead of the class object.
  (Github issue https://github.com/cython/cython/issues/7721)

* Declaring a ``__dict__`` attribute in a class as ``public`` or ``readonly``
  generated incorrect code.  It is now detected as an error.
  Patch by Anthony Donlon.  (Github issue https://github.com/cython/cython/issues/7823)

* A ``return value`` from within a ``prange()`` loop could silently return the
  default value of the return type instead of the user provided value.
  (Github issue https://github.com/cython/cython/issues/7587)

* Setting ``Py_LIMITED_API`` to a newer API version x.y than the current runtime
  (and its header files) is now detected and will explicitly fail to compile,
  rather than running into arbitrary C compile or runtime issues.
  (Github issue https://github.com/cython/cython/issues/7185)

* A ``cpdef enum`` with negative values changed to non-negative in Python 3.15.
  It now uses a dedicated enum implementation class to allow this.
  (Github issue https://github.com/cython/cython/issues/7185)

* Casting to an unresolved ``typeof()`` type (e.g. ``cython.cast(cython.typeof(x), ...)``
  where the type could not be inferred) crashed the compiler instead of reporting an error.
  Patch by Vladimir Saraikin.  (Github issue https://github.com/cython/cython/issues/7683)

* ``cpdef fused`` functions generated redundant code.
  (Github issue https://github.com/cython/cython/issues/7778)

* Automatic C++ STL conversions in different compiler directive contexts could generate
  invalid code duplications in C++ code.
  Original Patch by bjodah.  (Github issue https://github.com/cython/cython/issues/6981)

* Subscripting frozendicts with integer keys could fail in 3.3.0a1.

* When calling builtin types to create an instance, type inference could incorrectly
  assume ``type`` as the type of the result rather the concrete builtin type in 3.3.0a1.
  (Github issue https://github.com/cython/cython/issues/7848)

* The return type of some builtin methods were not correctly inferred in chained calls in 3.3.0a1.
  (Github issue https://github.com/cython/cython/issues/7664)

* Iterating over a container with an incorrectly declared item type could generate
  incorrect C code in 3.3.0a1.
  (Github issues https://github.com/cython/cython/issues/7775, https://github.com/cython/cython/issues/7889)

* ``NULL`` pointer comparisons could fail to compile with C++ in 3.3.0a1.
  Patch by Vyas Ramasubramani.  (Github issue https://github.com/cython/cython/issues/7766)

* A C helper function for mapping function arguments could be missing in 3.3.0a1.
  (Github issue https://github.com/cython/cython/issues/7785)

* MSVC could silently truncate long C string literals (including internal ones)
  at a 64k bytes border.  This is now worked around using C char arrays.
  (Github issue https://github.com/cython/cython/issues/7824)

* The virtualenv activation inside of ``cygdb`` when it is run from a virtualenv works in more cases.
  Original patch by Pierrick Koch and Ashutosh Varma.  (Github issues https://github.com/cython/cython/issues/1961, https://github.com/cython/cython/issues/3629)

* Some compiler directives failed to apply to Cython's build, which lead to
  unintentionally (slightly) increased wheel sizes.
  (Github issue https://github.com/cython/cython/issues/7801)

* Includes all fixes as of Cython 3.2.9.

3.2.9 (2026-07-24):

* Indexing into freshly created lists with an out-of-bounds index could crash.
  (Github issue https://github.com/cython/cython/issues/7793)

* Function arguments with default values could end up uninitialised in closures, leading to crashes.
  Patch by Anthony Donlon.  (Github issue https://github.com/cython/cython/issues/7782)

* ``bytearray.append(None)`` could crash. The optimised code was also lacking concurrency guards.
  (Github issue https://github.com/cython/cython/issues/7796)

* Some rare corner cases when concatenating text strings were resolved.
  (Github issue https://github.com/cython/cython/issues/7799)

* Assignments of builtin string types to typedefs of `object` could erroneously be rejected.
  (Github issue https://github.com/cython/cython/issues/7789)

* Subscripting ``type`` failed with a ``TypeError``.
  (Github issue https://github.com/cython/cython/issues/5563)

* Manually disabling ``CYTHON_VECTORCALL`` in CPython could lead to invalid C code.
  Patch by Florent Gallaire.  (Github issue https://github.com/cython/cython/issues/7807)

* Some internal Limited API version checks for Py3.12 were corrected.
  (Github issue https://github.com/cython/cython/issues/7845)

3.2.6 (2026-06-24):

* ``@functools.wraps()`` was broken in Py3.14+ for Cython compiled functions.
  (Github issue https://github.com/cython/cython/issues/7675)

* A double-free in the t-string code was fixed.
  (Github issue https://github.com/cython/cython/issues/7712)

* The ``-`` operator declarations for iterators in ``libcpp.vector`` we corrected.
  Patch by Vadim Markovtsev.  (Github issue https://github.com/cython/cython/issues/7717)

* The shared utility code module no longer uses a temporary file path that
  changed the C code on each generation.
  (Github issue https://github.com/cython/cython/issues/7723)

* On 32 bit platforms, cached constants are no longer made immortal during module import.
  (Github issue https://github.com/cython/cython/issues/7744)

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

* Setting the Limited API version macro ``Py_LIMITED_API`` in PyPy or GraalPython
  now enables the Limited API usage in these runtimes.  This will currently fail
  due to lack of support in the runtimes, but is intended for initial testing
  and future improvements.
  (Github issue https://github.com/cython/cython/issues/7831)

* Cython wheels now use a shared utility code module to reduce their size.
  (Github issue https://github.com/cython/cython/issues/7865)
