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  • v0.29.1 Changes

    November 24, 2018

    πŸ› Bugs fixed

    • 🏁 Extensions compiled with MinGW-64 under Windows could misinterpret integer objects larger than 15 bit and return incorrect results. (Github issue :issue:2670)

    • Cython no longer requires the source to be writable when copying its data into a memory view slice. Patch by Andrey Paramonov. (Github issue :issue:2644)

    • Line tracing of try-statements generated invalid C code. (Github issue :issue:2274)

    • When using the warn.undeclared directive, Cython's own code generated warnings that are now fixed. Patch by Nicolas Pauss. (Github issue :issue:2685)

    • Cython's memoryviews no longer require strides for setting the shape field but only the PyBUF_ND flag to be set. Patch by John Kirkham. (Github issue :issue:2716)

    • ⚠ Some C compiler warnings about unused memoryview code were fixed. Patch by Ho Cheuk Ting. (Github issue :issue:2588)

    • ⚠ A C compiler warning about implicit signed/unsigned conversion was fixed. (Github issue :issue:2729)

    • Assignments to C++ references returned by operator[] could fail to compile. (Github issue :issue:2671)

    • πŸ›  The power operator and the support for NumPy math functions were fixed in Pythran expressions. Patch by Serge Guelton. (Github issues :issue:2702, :issue:2709)

    • Signatures with memory view arguments now show the expected type when embedded in docstrings. Patch by Matthew Chan and Benjamin Weigel. (Github issue :issue:2634)

    • Some from ... cimport ... constructs were not correctly considered when searching modified dependencies in cythonize() to decide whether to recompile a module. Patch by KryΕ‘tof PilnÑček. (Github issue :issue:2638)

    • A struct field type in the cpython.array declarations was corrected. Patch by John Kirkham. (Github issue :issue:2712)

  • v0.29 Changes

    October 14, 2018

    πŸ”‹ Features added

    • PEP-489 multi-phase module initialisation has been enabled again. Module reloads in other subinterpreters raise an exception to prevent corruption of the static module state.

    • A set of mypy compatible PEP-484 declarations were added for Cython's C data types to integrate with static analysers in typed Python code. They are available in the Cython/Shadow.pyi module and describe the types in the special cython module that can be used for typing in Python code. Original patch by Julian Gethmann. (Github issue :issue:1965)

    • πŸ’… Memoryviews are supported in PEP-484/526 style type declarations. (Github issue :issue:2529)

    • πŸ‘ @cython.nogil is supported as a C-function decorator in Python code. (Github issue :issue:2557)

    • Raising exceptions from nogil code will automatically acquire the GIL, instead of requiring an explicit with gil block.

    • C++ functions can now be declared as potentially raising both C++ and Python exceptions, so that Cython can handle both correctly. (Github issue :issue:2615)

    • πŸ‘ cython.inline() supports a direct language_level keyword argument that was previously only available via a directive.

    • A new language level name 3str was added that mostly corresponds to language level 3, but keeps unprefixed string literals as type 'str' in both Py2 and Py3, and the builtin 'str' type unchanged. This will become the default in the next Cython release and is meant to help user code a) transition more easily to this new default and b) migrate to Python 3 source code semantics without making support for Python 2.x difficult.

    • In CPython 3.6 and later, looking up globals in the module dict is almost as fast as looking up C globals. (Github issue :issue:2313)

    • For a Python subclass of an extension type, repeated method calls to non-overridden cpdef methods can avoid the attribute lookup in Py3.6+, which makes them 4x faster. (Github issue :issue:2313)

    • (In-)equality comparisons of objects to integer literals are faster. (Github issue :issue:2188)

    • Some internal and 1-argument method calls are faster.

    • Modules that cimport many external extension types from other Cython modules execute less import requests during module initialisation.

    • Constant tuples and slices are deduplicated and only created once per module. (Github issue :issue:2292)

    • πŸ”Œ The coverage plugin considers more C file extensions such as .cc and .cxx. (Github issue :issue:2266)

    • The cythonize command accepts compile time variable values (as set by DEF) through the new -E option. Patch by Jerome Kieffer. (Github issue :issue:2315)

    • πŸ“¦ pyximport can import from namespace packages. Patch by Prakhar Goel. (Github issue :issue:2294)

    • Some missing numpy and CPython C-API declarations were added. Patch by John Kirkham. (Github issues :issue:2523, :issue:2520, :issue:2537)

    • Declarations for the pylifecycle C-API functions were added in a new .pxd file cpython.pylifecycle.

    • ⚑️ The Pythran support was updated to work with the latest Pythran 0.8.7. Original patch by Adrien Guinet. (Github issue :issue:2600)

    • %a is included in the string formatting types that are optimised into f-strings. In this case, it is also automatically mapped to %r in Python 2.x.

    • New C macro CYTHON_HEX_VERSION to access Cython's version in the same style as PY_VERSION_HEX.

    • Constants in libc.math are now declared as const to simplify their handling.

    • An additional check_size clause was added to the ctypedef class name specification to allow suppressing warnings when importing modules with backwards-compatible PyTypeObject size changes. Patch by Matti Picus. (Github issue :issue:2627)

    πŸ› Bugs fixed

    • πŸ‘» The exception handling in generators and coroutines under CPython 3.7 was adapted to the newly introduced exception stack. Users of Cython 0.28 who want to support Python 3.7 are encouraged to upgrade to 0.29 to avoid potentially incorrect error reporting and tracebacks. (Github issue :issue:1958)

    • Crash when importing a module under Stackless Python that was built for CPython. Patch by Anselm Kruis. (Github issue :issue:2534)

    • 2-value slicing of typed sequences failed if the start or stop index was None. Patch by Christian Gibson. (Github issue :issue:2508)

    • Multiplied string literals lost their factor when they are part of another constant expression (e.g. 'x' * 10 + 'y' => 'xy').

    • String formatting with the '%' operator didn't call the special __rmod__() method if the right side is a string subclass that implements it. (Python issue 28598)

    • The directive language_level=3 did not apply to the first token in the source file. (Github issue :issue:2230)

    • Overriding cpdef methods did not work in Python subclasses with slots. Note that this can have a performance impact on calls from Cython code. (Github issue :issue:1771)

    • πŸ›  Fix declarations of builtin or C types using strings in pure python mode. (Github issue :issue:2046)

    • Generator expressions and lambdas failed to compile in @cfunc functions. (Github issue :issue:459)

    • Global names with const types were not excluded from star-import assignments which could lead to invalid C code. (Github issue :issue:2621)

    • ⚠ Several internal function signatures were fixed that lead to warnings in gcc-8. (Github issue :issue:2363)

    • The numpy helper functions set_array_base() and get_array_base() were adapted to the current numpy C-API recommendations. Patch by Matti Picus. (Github issue :issue:2528)

    • ⚑️ Some NumPy related code was updated to avoid deprecated API usage. Original patch by jbrockmendel. (Github issue :issue:2559)

    • Several C++ STL declarations were extended and corrected. Patch by Valentin Valls. (Github issue :issue:2207)

    • C lines of the module init function were unconditionally not reported in exception stack traces. Patch by Jeroen Demeyer. (Github issue :issue:2492)

    • πŸ‘ When PEP-489 support is enabled, reloading the module overwrote any static module state. It now raises an exception instead, given that reloading is not actually supported.

    • πŸ‘» Object-returning, C++ exception throwing functions were not checking that the return value was non-null. Original patch by Matt Wozniski (Github issue :issue:2603)

    • The source file encoding detection could get confused if the c_string_encoding directive appeared within the first two lines. (Github issue :issue:2632)

    • ⚠ Cython generated modules no longer emit a warning during import when the size of the NumPy array type is larger than what was found at compile time. Instead, this is assumed to be a backwards compatible change on NumPy side.

    Other changes

    • ⚠ Cython now emits a warning when no language_level (2, 3 or '3str') is set explicitly, neither as a cythonize() option nor as a compiler directive. This is meant to prepare the transition of the default language level from currently Py2 to Py3, since that is what most new users will expect these days. The future default will, however, not enforce unicode literals, because this has proven a major obstacle in the support for both Python 2.x and 3.x. The next major release is intended to make this change, so that it will parse all code that does not request a specific language level as Python 3 code, but with str literals. The language level 2 will continue to be supported for an indefinite time.

    • πŸ“š The documentation was restructured, cleaned up and examples are now tested. The NumPy tutorial was also rewritten to simplify the running example. Contributed by Gabriel de Marmiesse. (Github issue :issue:2245)

    • πŸ— Cython compiles less of its own modules at build time to reduce the installed package size to about half of its previous size. This makes the compiler slightly slower, by about 5-7%.

  • v0.28.6 Changes

    November 01, 2018

    πŸ› Bugs fixed

    • 🏁 Extensions compiled with MinGW-64 under Windows could misinterpret integer objects larger than 15 bit and return incorrect results. (Github issue :issue:2670)

    • Multiplied string literals lost their factor when they are part of another constant expression (e.g. 'x' * 10 + 'y' => 'xy').

  • v0.28.5 Changes

    August 03, 2018

    πŸ› Bugs fixed

    • ⚑️ The discouraged usage of GCC's attribute optimize("Os") was replaced by the similar attribute cold to reduce the code impact of the module init functions. (Github issue :issue:2494)

    • πŸ›  A reference leak in Py2.x was fixed when comparing str to unicode for equality.

  • v0.28.4 Changes

    July 08, 2018

    πŸ› Bugs fixed

    • Reallowing tp_clear() in a subtype of an @no_gc_clear extension type generated an invalid C function call to the (non-existent) base type implementation. (Github issue :issue:2309)

    • πŸ‘» Exception catching based on a non-literal (runtime) tuple could fail to match the exception. (Github issue :issue:2425)

    • Compile fix for CPython 3.7.0a2. (Github issue :issue:2477)

  • v0.28.3 Changes

    May 27, 2018

    πŸ› Bugs fixed

    • Set iteration was broken in non-CPython since 0.28.

    • UnicodeEncodeError in Py2 when %s formatting is optimised for unicode strings. (Github issue :issue:2276)

    • β†ͺ Work around a crash bug in g++ 4.4.x by disabling the size reduction setting of the module init function in this version. (Github issue :issue:2235)

    • Crash when exceptions occur early during module initialisation. (Github issue :issue:2199)

  • v0.28.2 Changes

    April 13, 2018

    πŸ”‹ Features added

    • abs() is faster for Python long objects.

    • The C++11 methods front() and end() were added to the declaration of libcpp.string. Patch by Alex Huszagh. (Github issue :issue:2123)

    • The C++11 methods reserve() and bucket_count() are declared for libcpp.unordered_map. Patch by Valentin Valls. (Github issue :issue:2168)

    πŸ› Bugs fixed

    • The copy of a read-only memoryview was considered read-only as well, whereas a common reason to copy a read-only view is to make it writable. The result of the copying is now a writable buffer by default. (Github issue :issue:2134)

    • The switch statement generation failed to apply recursively to the body of converted if-statements.

    • πŸ‘» NULL was sometimes rejected as exception return value when the returned type is a fused pointer type. Patch by Callie LeFave. (Github issue :issue:2177)

    • πŸ›  Fixed compatibility with PyPy 5.11. Patch by Matti Picus. (Github issue :issue:2165)

    Other changes

    • The NumPy tutorial was rewritten to use memoryviews instead of the older buffer declaration syntax. Contributed by Gabriel de Marmiesse. (Github issue :issue:2162)
  • v0.28.1 Changes

    March 18, 2018

    πŸ› Bugs fixed

    • PyFrozenSet_New() was accidentally used in PyPy where it is missing from the C-API.

    • Assignment between some C++ templated types were incorrectly rejected when the templates mix const with ctypedef. (Github issue :issue:2148)

    • Undeclared C++ no-args constructors in subclasses could make the compilation fail if the base class constructor was declared without nogil. (Github issue :issue:2157)

    • Bytes %-formatting inferred basestring (bytes or unicode) as result type in some cases where bytes would have been safe to infer. (Github issue :issue:2153)

    • None was accidentally disallowed as typed return value of dict.pop(). (Github issue :issue:2152)

  • v0.28 Changes

    March 13, 2018

    πŸ”‹ Features added

    • Cdef classes can now multiply inherit from ordinary Python classes. (The primary base must still be a c class, possibly object, and the other bases must not be cdef classes.)

    • πŸ‘ Type inference is now supported for Pythran compiled NumPy expressions. Patch by Nils Braun. (Github issue :issue:1954)

    • The const modifier can be applied to memoryview declarations to allow read-only buffers as input. (Github issues :issue:1605, :issue:1869)

    • πŸ“„ C code in the docstring of a cdef extern block is copied verbatimly into the generated file. Patch by Jeroen Demeyer. (Github issue :issue:1915)

    • When compiling with gcc, the module init function is now tuned for small code size instead of whatever compile flags were provided externally. Cython now also disables some code intensive optimisations in that function to further reduce the code size. (Github issue :issue:2102)

    • Decorating an async coroutine with @cython.iterable_coroutine changes its type at compile time to make it iterable. While this is not strictly in line with PEP-492, it improves the interoperability with old-style coroutines that use yield from instead of await.

    • πŸ‘ The IPython magic has preliminary support for JupyterLab. (Github issue :issue:1775)

    • πŸ‘ The new TSS C-API in CPython 3.7 is supported and has been backported. Patch by Naotoshi Seo. (Github issue :issue:1932)

    • Cython knows the new Py_tss_t type defined in PEP-539 and automatically initialises variables declared with that type to Py_tss_NEEDS_INIT, a value which cannot be used outside of static assignments.

    • 🚚 The set methods .remove() and .discard() are optimised. Patch by Antoine Pitrou. (Github issue :issue:2042)

    • dict.pop() is optimised. Original patch by Antoine Pitrou. (Github issue :issue:2047)

    • Iteration over sets and frozensets is optimised. (Github issue :issue:2048)

    • Safe integer loops (< range(230)) are automatically optimised into C loops.

    • alist.extend([a,b,c]) is optimised into sequential list.append() calls for short literal sequences.

    • Calls to builtin methods that are not specifically optimised into C-API calls now use a cache that avoids repeated lookups of the underlying C function. (Github issue :issue:2054)

    • Single argument function calls can avoid the argument tuple creation in some cases.

    • Some redundant extension type checks are avoided.

    • Formatting C enum values in f-strings is faster, as well as some other special cases.

    • String formatting with the '%' operator is optimised into f-strings in simple cases.

    • Subscripting (item access) is faster in some cases.

    • Some bytearray operations have been optimised similar to bytes.

    • Some PEP-484/526 container type declarations are now considered for loop optimisations.

    • Indexing into memoryview slices with view[i][j] is now optimised into view[i, j].

    • Python compatible cython.* types can now be mixed with type declarations in Cython syntax.

    • Name lookups in the module and in classes are faster.

    • Python attribute lookups on extension types without instance dict are faster.

    • 🚦 Some missing signals were added to libc/signal.pxd. Patch by Jeroen Demeyer. (Github issue :issue:1914)

    • ⚠ The warning about repeated extern declarations is now visible by default. (Github issue :issue:1874)

    • πŸ‘» The exception handling of the function types used by CPython's type slot functions was corrected to match the de-facto standard behaviour, so that code that uses them directly benefits from automatic and correct exception propagation. Patch by Jeroen Demeyer. (Github issue :issue:1980)

    • Defining the macro CYTHON_NO_PYINIT_EXPORT will prevent the module init function from being exported as symbol, e.g. when linking modules statically in an embedding setup. Patch by AraHaan. (Github issue :issue:1944)

    πŸ› Bugs fixed

    • If a module name is explicitly provided for an Extension() that is compiled via cythonize(), it was previously ignored and replaced by the source file name. It can now be used to override the target module name, e.g. for compiling prefixed accelerator modules from Python files. (Github issue :issue:2038)

    • The arguments of the num_threads parameter of parallel sections were not sufficiently validated and could lead to invalid C code. (Github issue :issue:1957)

    • πŸ‘» Catching exceptions with a non-trivial exception pattern could call into CPython with a live exception set. This triggered incorrect behaviour and crashes, especially in CPython 3.7.

    • The signature of the special __richcmp__() method was corrected to recognise the type of the first argument as self. It was previously treated as plain object, but CPython actually guarantees that it always has the correct type. Note: this can change the semantics of user code that previously relied on self being untyped.

    • Some Python 3 exceptions were not recognised as builtins when running Cython under Python 2.

    • Some async helper functions were not defined in the generated C code when compiling simple async code. (Github issue :issue:2075)

    • Line tracing did not include generators and coroutines. (Github issue :issue:1949)

    • C++ declarations for unordered_map were corrected. Patch by Michael Schatzow. (Github issue :issue:1484)

    • Iterator declarations in C++ deque and vector were corrected. Patch by Alex Huszagh. (Github issue :issue:1870)

    • The const modifiers in the C++ string declarations were corrected, together with the coercion behaviour of string literals into C++ strings. (Github issue :issue:2132)

    • Some declaration types in libc.limits were corrected. Patch by Jeroen Demeyer. (Github issue :issue:2016)

    • was not accepted on Python classes with an @cython.cclass decorator. (Github issue :issue:2040)

    • Cython no longer creates useless and incorrect PyInstanceMethod wrappers for methods in Python 3. Patch by Jeroen Demeyer. (Github issue :issue:2105)

    • The builtin bytearray type could not be used as base type of cdef classes. (Github issue :issue:2106)

    Other changes

  • v0.27.3 Changes

    November 03, 2017

    πŸ› Bugs fixed

    • String forward references to extension types like @cython.locals(x="ExtType") failed to find the named type. (Github issue :issue:1962)

    • NumPy slicing generated incorrect results when compiled with Pythran. Original patch by Serge Guelton (Github issue :issue:1946).

    • πŸ›  Fix "undefined reference" linker error for generators on Windows in Py3.3-3.5. (Github issue :issue:1968)

    • Adapt to recent C-API change of PyThreadState in CPython 3.7.

    • πŸ›  Fix signature of PyWeakref_GetObject() API declaration. Patch by Jeroen Demeyer (Github issue :issue:1975).