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Cython Changelog

What's new in Cython 0.23.2

Sep 11, 2015
  • Bugs fixed:
  • Compiler crash when analysing some optimised expressions.
  • Coverage plugin was adapted to coverage.py 4.0 beta 2.
  • C++ destructor calls could fail when '&' operator is overwritten.
  • Incorrect C literal generation for large integers in compile-time evaluated DEF expressions and constant folded expressions.
  • Byte string constants could end up as Unicode strings when originating from compile-time evaluated DEF expressions.
  • Invalid C code when caching known builtin methods. This fixes ticket 860.
  • ino_t in posix.types was not declared as unsigned.
  • Declarations in libcpp/memory.pxd were missing operator!(). Patch by Leo Razoumov.
  • Static cdef methods can now be declared in .pxd files.

New in Cython 0.23.1 (Aug 23, 2015)

  • Bugs fixed:
  • Invalid C code for generators. This fixes ticket 858.
  • Invalid C code for some builtin methods. This fixes ticket 856.
  • Invalid C code for unused local buffer variables. This fixes ticket 154.
  • Test failures on 32bit systems. This fixes ticket 857.
  • Code that uses "from xyz import *" and global C struct/union/array variables could fail to compile due to missing helper functions. This fixes ticket 851.
  • Misnamed PEP 492 coroutine property cr_yieldfrom renamed to cr_await to match CPython.
  • Missing deallocation code for C++ object attributes in certain extension class hierarchies.
  • Crash when async coroutine was not awaited.
  • Compiler crash on yield in signature annotations and default argument values. Both are forbidden now.
  • Compiler crash on certain constructs in finally clauses.
  • Cython failed to build when CPython's pgen is installed.

New in Cython 0.23 (Aug 23, 2015)

  • Features added:
  • PEP 492 (async/await) was implemented. See https://www.python.org/dev/peps/pep-0492/
  • PEP 448 (Additional Unpacking Generalizations) was implemented. See https://www.python.org/dev/peps/pep-0448/
  • Support for coverage.py 4.0+ can be enabled by adding the plugin "Cython.Coverage" to the ".coveragerc" config file.
  • Annotated HTML source pages can integrate (XML) coverage reports.
  • Tracing is supported in nogil functions/sections and module init code.
  • When generators are used in a Cython module and the module imports the modules "inspect" and/or "asyncio", Cython enables interoperability by patching these modules during the import to recognise Cython's internal generator and coroutine types. This can be disabled by C compiling the module with "-D CYTHON_PATCH_ASYNCIO=0" or "-D CYTHON_PATCH_INSPECT=0"
  • When generators or coroutines are used in a Cython module, their types are registered with the Generator and Coroutine ABCs in the collections or collections.abc stdlib module at import time to enable interoperability with code that needs to detect and process Python generators/coroutines. These ABCs were added in CPython 3.5 and are available for older Python versions through the backports_abc module on PyPI. See https://bugs.python.org/issue24018
  • Adding/subtracting/dividing/modulus and equality comparisons with constant Python floats and small integers are faster.
  • Binary and/or/xor/rshift operations with small constant Python integers are faster.
  • When called on generator expressions, the builtins all(), any(), dict(), list(), set(), sorted() and unicode.join() avoid the generator iteration overhead by inlining a part of their functionality into the for-loop.
  • Keyword argument dicts are no longer copied on function entry when they are not being used or only passed through to other function calls (e.g. in wrapper functions).
  • The PyTypeObject declaration in cpython.object was extended.
  • The builtin type type is now declared as PyTypeObject in source, allowing for extern functions taking type parameters to have the correct C signatures. Note that this might break code that uses type just for passing around Python types in typed variables. Removing the type declaration provides a backwards compatible fix.
  • wraparound() and boundscheck() are available as no-ops in pure Python mode.
  • Const iterators were added to the provided C++ STL declarations.
  • Smart pointers were added to the provided C++ STL declarations. Patch by Daniel Filonik.
  • NULL is allowed as default argument when embedding signatures. This fixes ticket 843.
  • When compiling with --embed, the internal module name is changed to __main__ to allow arbitrary program names, including those that would be invalid for modules. Note that this prevents reuse of the generated C code as an importable module.
  • External C++ classes that overload the assignment operator can be used. Patch by Ian Henriksen.
  • Support operator bool() for C++ classes so they can be used in if statements.
  • Bugs fixed:
  • Calling "yield from" from Python on a Cython generator that returned a value triggered a crash in CPython. This is now being worked around. See https://bugs.python.org/issue23996
  • Language level 3 did not enable true division (a.k.a. float division) for integer operands.
  • Functions with fused argument types that included a generic 'object' fallback could end up using that fallback also for other explicitly listed object types.
  • Relative cimports could accidentally fall back to trying an absolute cimport on failure.
  • The result of calling a C struct constructor no longer requires an intermediate assignment when coercing to a Python dict.
  • C++ exception declarations with mapping functions could fail to compile when pre-declared in .pxd files.
  • cpdef void methods are now permitted.
  • abs(cint) could fail to compile in MSVC and used sub-optimal code in C++. Patch by David Vierra, original patch by Michael Enßlin.
  • Buffer index calculations using index variables with small C integer types could overflow for large buffer sizes. Original patch by David Vierra.
  • C unions use a saner way to coerce from and to Python dicts.
  • When compiling a module foo.pyx, the directories in sys.path are no longer searched when looking for foo.pxd. Patch by Jeroen Demeyer.
  • Memory leaks in the embedding main function were fixed. Original patch by Michael Enßlin.
  • Some complex Python expressions could fail to compile inside of finally clauses.
  • Unprefixed 'str' literals were not supported as C varargs arguments.
  • Fixed type errors in conversion enum types to/from Python. Note that this imposes stricter correctness requirements on enum declarations.
  • Other changes:
  • Changed mangling scheme in header files generated by cdef api declarations.
  • Installation under CPython 3.3+ no longer requires a pass of the 2to3 tool. This also makes it possible to run Cython in Python 3.3+ from a source checkout without installing it first. Patch by Petr Viktorin.
  • jedi-typer.py (in Tools/) was extended and renamed to jedityper.py (to make it importable) and now works with and requires Jedi 0.9. Patch by Tzer-jen Wei.

New in Cython 0.23 (Aug 10, 2015)

  • Features added:
  • PEP 492 (async/await) was implemented. See https://www.python.org/dev/peps/pep-0492/
  • PEP 448 (Additional Unpacking Generalizations) was implemented. See https://www.python.org/dev/peps/pep-0448/
  • Support for coverage.py 4.0+ can be enabled by adding the plugin "Cython.Coverage" to the ".coveragerc" config file.
  • Annotated HTML source pages can integrate (XML) coverage reports.
  • Tracing is supported in nogil functions/sections and module init code.
  • When generators are used in a Cython module and the module imports the modules "inspect" and/or "asyncio", Cython enables interoperability by patching these modules during the import to recognise Cython's internal generator and coroutine types. This can be disabled by C compiling the module with "-D CYTHON_PATCH_ASYNCIO=0" or "-D CYTHON_PATCH_INSPECT=0"
  • When generators or coroutines are used in a Cython module, their types are registered with the Generator and Coroutine ABCs in the collections or collections.abc stdlib module at import time to enable interoperability with code that needs to detect and process Python generators/coroutines. These ABCs were added in CPython 3.5 and are available for older Python versions through the backports_abc module on PyPI. See https://bugs.python.org/issue24018
  • Adding/subtracting/dividing/modulus and equality comparisons with constant Python floats and small integers are faster.
  • Binary and/or/xor/rshift operations with small constant Python integers are faster.
  • When called on generator expressions, the builtins all(), any(), dict(), list(), set(), sorted() and unicode.join() avoid the generator iteration overhead by inlining a part of their functionality into the for-loop.
  • Keyword argument dicts are no longer copied on function entry when they are not being used or only passed through to other function calls (e.g. in wrapper functions).
  • The PyTypeObject declaration in cpython.object was extended.
  • The builtin type type is now declared as PyTypeObject in source, allowing for extern functions taking type parameters to have the correct C signatures. Note that this might break code that uses type just for passing around Python types in typed variables. Removing the type declaration provides a backwards compatible fix.
  • wraparound() and boundscheck() are available as no-ops in pure Python mode.
  • Const iterators were added to the provided C++ STL declarations.
  • Smart pointers were added to the provided C++ STL declarations. Patch by Daniel Filonik.
  • NULL is allowed as default argument when embedding signatures. This fixes ticket 843.
  • When compiling with --embed, the internal module name is changed to __main__ to allow arbitrary program names, including those that would be invalid for modules. Note that this prevents reuse of the generated C code as an importable module.
  • External C++ classes that overload the assignment operator can be used. Patch by Ian Henriksen.
  • Support operator bool() for C++ classes so they can be used in if statements.
  • Bugs fixed:
  • Calling "yield from" from Python on a Cython generator that returned a value triggered a crash in CPython. This is now being worked around. See https://bugs.python.org/issue23996
  • Language level 3 did not enable true division (a.k.a. float division) for integer operands.
  • Functions with fused argument types that included a generic 'object' fallback could end up using that fallback also for other explicitly listed object types.
  • Relative cimports could accidentally fall back to trying an absolute cimport on failure.
  • The result of calling a C struct constructor no longer requires an intermediate assignment when coercing to a Python dict.
  • C++ exception declarations with mapping functions could fail to compile when pre-declared in .pxd files.
  • cpdef void methods are now permitted.
  • abs(cint) could fail to compile in MSVC and used sub-optimal code in C++. Patch by David Vierra, original patch by Michael Enßlin.
  • Buffer index calculations using index variables with small C integer types could overflow for large buffer sizes. Original patch by David Vierra.
  • C unions use a saner way to coerce from and to Python dicts.
  • When compiling a module foo.pyx, the directories in sys.path are no longer searched when looking for foo.pxd. Patch by Jeroen Demeyer.
  • Memory leaks in the embedding main function were fixed. Original patch by Michael Enßlin.
  • Some complex Python expressions could fail to compile inside of finally clauses.
  • Unprefixed 'str' literals were not supported as C varargs arguments.
  • Fixed type errors in conversion enum types to/from Python. Note that this imposes stricter correctness requirements on enum declarations.
  • Other changes:
  • Changed mangling scheme in header files generated by cdef api declarations.
  • Installation under CPython 3.3+ no longer requires a pass of the 2to3 tool. This also makes it possible to run Cython in Python 3.3+ from a source checkout without installing it first. Patch by Petr Viktorin.
  • jedi-typer.py (in Tools/) was extended and renamed to jedityper.py (to make it importable) and now works with and requires Jedi 0.9. Patch by Tzer-jen Wei.

New in Cython 0.22.1 (Jun 22, 2015)

  • Bugs fixed:
  • Crash when returning values on generator termination.
  • In some cases, exceptions raised during internal isinstance() checks were not propagated.
  • Runtime reported file paths of source files (e.g for profiling and tracing) are now relative to the build root directory instead of the main source file.
  • Tracing exception handling code could enter the trace function with an active exception set.
  • The internal generator function type was not shared across modules.
  • Comparisons of (inferred) ctuples failed to compile.
  • Closures inside of cdef functions returning void failed to compile.
  • Using const C++ references in intermediate parts of longer expressions could fail to compile.
  • C++ exception declarations with mapping functions could fail to compile when pre-declared in .pxd files.
  • C++ compilation could fail with an ambiguity error in recent MacOS-X Xcode versions.
  • C compilation could fail in pypy3.
  • Fixed a memory leak in the compiler when compiling multiple modules.
  • When compiling multiple modules, external library dependencies could leak into later compiler runs. Fix by Jeroen Demeyer. This fixes ticket 845.

New in Cython 0.22 (Feb 12, 2015)

  • Features added:
  • C functions can coerce to Python functions, which allows passing them around as callable objects.
  • C arrays can be assigned by value and auto-coerce from Python iterables and to Python lists (and tuples).
  • Extern C functions can now be declared as cpdef to export them to the module's Python namespace. Extern C functions in pxd files export their values to their own module, iff it exists.
  • Anonymous C tuple types can be declared as (ctype1, ctype2, ...).
  • PEP 479: turn accidental StopIteration exceptions that exit generators into a RuntimeError, activated with future import "generator_stop". See http://legacy.python.org/dev/peps/pep-0479/
  • Looping over reversed(range()) is optimised in the same way as range(). Patch by Favian Contreras.
  • Bugs fixed:
  • Mismatching 'except' declarations on signatures in .pxd and .pyx files failed to produce a compile error.
  • Failure to find any files for the path pattern(s) passed into cythonize() is now an error to more easily detect accidental typos.
  • The logaddexp family of functions in numpy.math now has correct declarations.
  • In Py2.6/7 and Py3.2, simple Cython memory views could accidentally be interpreted as non-contiguous by CPython, which could trigger a CPython bug when copying data from them, thus leading to data corruption. See CPython issues 12834 and 23349.
  • Other changes:
  • Preliminary support for defining the Cython language with a formal grammar. To try parsing your files against this grammar, use the --formal_grammar directive. Experimental.
  • _ is no longer considered a cacheable builtin as it could interfere with gettext.
  • Cythonize-computed metadata now cached in the generated C files.
  • Several corrections and extensions in numpy, cpython, and libcpp pxd files.

New in Cython 0.21.2 (Dec 29, 2014)

  • 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.

New in Cython 0.21.1 (Dec 18, 2014)

  • 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.

New in Cython 0.21.1 Pre (Oct 15, 2014)

  • Features added:
  • C functions can coerce to Python functions, which allows passing them around as callable objects.
  • New cythonize option -a to generate the annotated HTML source view.
  • Extern C functions can now be declared as cpdef to export them to the module's Python namespace. Extern C functions in pxd files export their values to their own module, iff it exists.
  • 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:
  • Mismatching 'except' declarations on signatures in .pxd and .pyx files failed to produce a compile error.
  • 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).
  • 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.

New in Cython 0.21 (Sep 11, 2014)

  • 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 http://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 http://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.

New in Cython 0.21 Alpha 1 (Aug 1, 2014)

  • Features added:
  • 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 http://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``.
  • Optimizations:
  • 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.
  • Cascaded assignments (a = b = ...) try to minimise the number of type coercions.
  • The Python expression "2 ** N" is optimised into bit shifting. See http://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:
  • 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.
  • Other changes:
  • 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.

New in Cython 0.20.2 (Jun 17, 2014)

  • 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.

New in Cython 0.20.2 Beta 1 (May 30, 2014)

  • Features added:
  • Some optimizations for set/frozenset instantiation.
  • Support for C++ unordered_set and unordered_map.
  • Bugs fixed:
  • Access to attributes of optimized built-in 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.

New in Cython 0.20.1 (Mar 15, 2014)

  • 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

New in Cython 0.19.2 (Oct 18, 2013)

  • Some standard declarations were fixed or updated, including the previously
  • incorrect declaration of ``PyBuffer_FillInfo()`` and some missing bits in
  • ``libc.math``.
  • Heap allocated subtypes of ``type`` used the wrong base type struct at the
  • C level.
  • Calling the unbound method dict.keys/value/items() in dict subtypes could
  • call the bound object method instead of the unbound supertype method.
  • "yield" wasn't supported in "return" value expressions.
  • Using the "bint" type in memory views lead to unexpected results.
  • It is now an error.
  • Assignments to global/closure variables could catch them in an illegal state
  • while deallocating the old value.

New in Cython 0.19.1 (Jun 14, 2013)

  • Features:
  • Completely empty C-API structs for extension type slots (protocols like number/mapping/sequence) are no longer generated into the C code.
  • Docstrings that directly follow a public/readonly attribute declaration in a cdef class will be used as docstring of the auto-generated property. This fixes ticket 206.
  • The automatic signature documentation tries to preserve more semantics of default arguments and argument types. Specifically, bint arguments now appear as type bool.
  • A warning is emitted when negative literal indices are found inside of a code section that disables wraparound handling. This helps with fixing invalid code that might fail in the face of future compiler optimizations.
  • Constant folding for boolean expressions (and/or) was improved.
  • Added a build_dir option to cythonize() which allows one to place the generated .c files outside the source tree.
  • General Improvements and Bug Fixes:
  • isinstance(X, type) failed to get optimized into a call to PyType_Check(), as done for other builtin types.
  • A spurious from datetime cimport * was removed from the cpython declaration package. This means that the datetime declarations (added in 0.19) are no longer available directly from the cpython namespace, but only from cpython.datetime. This is the correct way of doing it because the declarations refer to a standard library module, not the core CPython C-API itself.
  • The C code for extension types is now generated in topological order instead of source code order to avoid C compiler errors about missing declarations for subtypes that are defined before their parent.
  • The memoryview type name no longer shows up in the module dict of modules that use memory views. This fixes trac ticket 775.
  • Regression in 0.19 that rejected valid C expressions from being used in C array size declarations.
  • In C++ mode, the C99-only keyword restrict could accidentally be seen by the GNU C++ compiler. It is now specially handled for both GCC and MSVC.
  • Testing large (> int) C integer values for their truth value could fail due to integer wrap-around.

New in Cython 0.17.1 (Oct 1, 2012)

  • A reference leak was fixed in the new dict iteration code when the loop target was not a plain variable but an unpacked tuple.
  • Memory views did not handle the special case of a NULL buffer strides value, as allowed by PEP3118.

New in Cython 0.17 (Sep 21, 2012)

  • Features:
  • Alpha quality support for compiling and running Cython generated extension modules in PyPy (through cpyext). Note that this requires at leastPyPy 1.9 and in many cases also adaptations in user code, especially to avoid borrowed references when no owned reference is being held directly in C space (a reference in a Python list or dict is not enough, for example). See the documentation on porting Cython code to PyPy.
  • "yield from" is supported (PEP 380) and a couple of minor problems with generators were fixed.
  • C++ STL container classes automatically coerce from and to the equivalent Python container types on typed assignments and casts. Usage examples are here. Note that the data in the containers is copied during this conversion.
  • C++ iterators can now be iterated over using for x in cpp_container whenever cpp_container has begin() and end() methods returning objects satisfying the iterator pattern (that is, it can be incremented, dereferenced, and compared (for non-equality)).
  • cdef classes can now have C++ class members (provided a zero-argument constructor exists)
  • A new cpython.array standard cimport file allows to efficiently talk to the stdlib array.array data type in Python 2. Since CPython does not export an official C-API for this module, it receives special casing by the compiler in order to avoid setup overhead on user side. In Python 3, both buffers and memory views on the array type already worked out of the box with earlier versions of Cython due to the native support for the buffer interface in the Py3 array module.
  • Fast dict iteration is now enabled optimistically also for untyped variables when the common iteration methods are used.
  • The unicode string processing code was adapted for the upcoming CPython 3.3 (PEP 393, new Unicode buffer layout).
  • Buffer arguments and memory view arguments in Python functions can be declared "not None" to raise a TypeError on None input.
  • c(p)def functions in pure mode can specify their return type with "@cython.returns()".
  • Automatic dispatch for fused functions with memoryview arguments
  • Support newaxis indexing for memoryviews
  • Support decorators for fused functions
  • General Improvements and Bug Fixes:
  • Old-style Py2 imports did not work reliably in Python 3.x and were broken in Python 3.3. Regardless of this fix, it's generally best to be explicit about relative and global imports in Cython code because old-style imports have a higher overhead. To this end, "from __future__ import absolute_import" is supported in Python/Cython 2.x code now (previous versions of Cython already used it when compiling Python 3 code).
  • Stricter constraints on the inline and final modifiers. If your code does not compile due to this change, chances are these modifiers were previously being ignored by the compiler and can be removed without any performance regression.
  • Exceptions are always instantiated while raising them (as in Python), instead of risking to instantiate them in potentially unsafe situations when they need to be handled or otherwise processed.
  • locals() properly ignores names that do not have Python compatible types (including automatically inferred types).
  • Some garbage collection issues of memory views were fixed.
  • User declared char* types are now recognised as such and auto-coerce to and from Python bytes strings.
  • libc.string provides a convenience declaration for const uchar in addition to const char.
  • Modules generated by @cython.inline() are written into the directory pointed to by the environment variable CYTHON_CACHE_DIR if set.
  • numpy.pxd compiles in Python 3 mode.
  • callable() and next() compile to more efficient C code.
  • list.append() is faster on average.
  • Several C compiler warnings were fixed.
  • Several bugs related to memoryviews and fused types were fixed.
  • Several bug-fixes and improvements related to cythonize(), including ccache-style caching.

New in Cython 0.16 (May 18, 2012)

  • Features:
  • Enhancements to Cython's function type (support for weak references, default arguments, code objects, dynamic attributes, classmethods, staticmethods, and more)
  • Fused Types - Template-like support for functions and methods
  • Typed views on memory - Support for efficient direct and indirect buffers (indexing, slicing, transposing, ...)
  • super() without arguments
  • Final cdef methods (which translate into direct calls on known instances)
  • General Improvements and Bug Fixes:
  • support default arguments for closures
  • search sys.path for pxd files
  • support C++ template casting
  • faster traceback building and faster generator termination
  • support inplace operators on indexed buffers
  • fix alignment handling for record types in buffer support
  • allow nested prange sections