Cython v3.0.0 Release Notes
Release Date: 2020-04-23 // almost 5 years ago-
π Features added
Cython functions now use the
PEP-590
_ vectorcall protocol in Py3.7+. Patch by Jeroen Demeyer. (Github issue :issue:2263
)π Unicode identifiers are supported in Cython code (
PEP-3131
_). Patch by David Woods. (Github issue :issue:2601
)π Unicode module names and imports are supported. Patch by David Woods. (Github issue :issue:
3119
)π Annotations are no longer parsed, keeping them as strings following
PEP-563
_. Patch by David Woods. (Github issue :issue:3285
)Preliminary support for the CPython's
Py_LIMITED_API
(stable ABI) is available by setting theCYTHON_LIMITED_API
C macro. Note that the support is currently in an early stage and many features do not yet work. You currently still have to definePy_LIMITED_API
externally in order to restrict the API usage. This will change when the feature stabilises. Patches by Eddie Elizondo and David Woods. (Github issues :issue:3223
, :issue:3311
, :issue:3501
)The dispatch to fused functions is now linear in the number of arguments, which makes it much faster, often 2x or more, and several times faster for larger fused types with many specialisations. Patch by will-ca. (Github issue :issue:
1385
)with gil/nogil
statements can be conditional based on compile-time constants, e.g. fused type checks. Patch by Noam Hershtig. (Github issue :issue:2579
)const
can be used together with fused types. Patch by Thomas Vincent. (Github issue :issue:1772
)Reimports of already imported modules are substantially faster. (Github issue :issue:
2854
)π Positional-only arguments are supported in Python functions (
PEP-570
_). Patch by Josh Tobin. (Github issue :issue:2915
)π The
volatile
C modifier is supported in Cython code. Patch by Jeroen Demeyer. (Github issue :issue:1667
)@cython.trashcan(True)
can be used on an extension type to enable the CPython :ref:trashcan
. This allows deallocating deeply recursive objects without overflowing the stack. Patch by Jeroen Demeyer. (Github issue :issue:2842
)Inlined properties can be defined for external extension types. Patch by Matti Picus. (Github issue :issue:
2640
, redone later in :issue:3571
)The
str()
builtin now callsPyObject_Str()
instead of going through a Python call. Patch by William Ayd. (Github issue :issue:3279
)String concatenation can now happen in place if possible, by extending the existing string rather than always creating a new one. Patch by David Woods. (Github issue :issue:
3453
)Multiplication of Python numbers with small constant integers is faster. (Github issue :issue:
2808
)Some list copying is avoided internally when a new list needs to be created but we already have a fresh one. (Github issue :issue:
3494
)Extension types that do not need their own
tp_new
implementation (because they have no object attributes etc.) directly inherit the implementation of their parent type if possible. (Github issue :issue:1555
)The attributes
gen.gi_frame
andcoro.cr_frame
of Cython compiled generators and coroutines now return an actual frame object for introspection. (Github issue :issue:2306
)Several declarations in
cpython.*
,libc.*
andlibcpp.*
were added. Patches by Jeroen Demeyer, Matthew Edwards, Chris Gyurgyik, Jerome Kieffer and Zackery Spytz. (Github issues :issue:3468
, :issue:3332
, :issue:3202
, :issue:3188
, :issue:3179
, :issue:2891
, :issue:2826
, :issue:2713
)π Deprecated NumPy API usages were removed from
numpy.pxd
. Patch by Matti Picus. (Github issue :issue:3365
)cython.inline()
now sets theNPY_NO_DEPRECATED_API=NPY_1_7_API_VERSION
C macro automatically whennumpy
is imported in the code, to avoid C compiler warnings about deprecated NumPy C-API usage.The builtin
abs()
function can now be used on C numbers in nogil code. Patch by Elliott Sales de Andrade. (Github issue :issue:2748
)PEP-479
_ (generator_stop
) is now enabled by default with language level 3. (Github issue :issue:2580
)π The
cython.view.array
type supports inheritance. Patch by David Woods. (Github issue :issue:3413
)Code annotation accepts a new debugging argument
--annotate-fullc
that will include the complete syntax highlighted C file in the HTML output. (Github issue :issue:2855
)β
--no-capture
added toruntests.py
to prevent stdout/stderr capturing during srctree tests. Patch by Matti Picus. (Github issue :issue:2701
)π
--no-docstrings
option added tocythonize
script. Original patch by mo-han. (Github issue :issue:2889
)π
cygdb
gives better error messages when it fails to initialise the Python runtime support in gdb. Patch by Volker Weissmann. (Github issue :issue:3489
)π The Pythran
shape
attribute is supported. Patch by Serge Guelton. (Github issue :issue:3307
)
π Bugs fixed
The unicode methods
.upper()
,.lower()
and.title()
were incorrectly optimised for single character input values and only returned the first character if multiple characters should have been returned. They now use the original Python methods again.Fused argument types were not correctly handled in type annotations and
cython.locals()
. Patch by David Woods. (Github issues :issue:3391
, :issue:3142
)Diverging from the usual behaviour,
len(memoryview)
,len(char*)
andlen(Py_UNICODE*)
returned an unsignedsize_t
value. They now return a signedPy_ssize_t
, like other usages oflen()
.Nested dict literals in function call kwargs could incorrectly raise an error about duplicate keyword arguments, which are allowed when passing them from dict literals. (Github issue :issue:
2963
)Item access (subscripting) with integer indices/keys always tried the Sequence protocol before the Mapping protocol, which diverged from Python semantics. It now passes through the Mapping protocol first when supported. (Github issue :issue:
1807
)Name lookups in class bodies no longer go through an attribute lookup. Patch by Jeroen Demeyer. (Github issue :issue:
3100
)Broadcast assignments to a multi-dimensional memory view slice could end up in the wrong places when the underlying memory view is known to be contiguous but the slice is not. (Github issue :issue:
2941
)Pickling unbound methods of Python classes failed. Patch by Pierre Glaser. (Github issue :issue:
2972
)The
Py_hash_t
type failed to accept arbitrary "index" values. (Github issue :issue:2752
)The first function line number of functions with decorators pointed to the signature line and not the first decorator line, as in Python. Patch by Felix KohlgrΓΌber. (Github issue :issue:
2536
)Constant integer expressions that used a negative exponent were evaluated as integer 0 instead of the expected float value. Patch by KryΕ‘tof PilnΓ‘Δek. (Github issue :issue:
2133
)The
cython.declare()
andcython.cast()
functions could fail in pure mode. Patch by Dmitry Shesterkin. (Github issue :issue:3244
)__doc__
was not available inside of the class body during class creation. (Github issue :issue:1635
)Setting
language_level=2
in a file did not work iflanguage_level=3
was enabled globally before. Patch by Jeroen Demeyer. (Github issue :issue:2791
)__init__.pyx
files were not always considered as package indicators. (Github issue :issue:2665
)Compiling package
__init__
files could fail under Windows due to an undefined export symbol. (Github issue :issue:2968
)β A C compiler cast warning was resolved. Patch by Michael Buesch. (Github issue :issue:
2775
)Binding staticmethods of Cython functions were not behaving like Python methods. Patch by Jeroen Demeyer. (Github issue :issue:
3106
, :issue:3102
)Memoryviews failed to compile when the
cache_builtins
feature was disabled. Patch by David Woods. (Github issue :issue:3406
)
Other changes
0οΈβ£ The default language level was changed to
3str
, i.e. Python 3 semantics, but withstr
literals (also in Python 2.7). This is a backwards incompatible change from the previous default of Python 2 semantics. The previous behaviour is available through the directivelanguage_level=2
. (Github issue :issue:2565
)Cython no longer generates
__qualname__
attributes for classes in Python 2.x since they are problematic there and not correctly maintained for subclasses. Patch by Jeroen Demeyer. (Github issue :issue:2772
)π¨ Source file fingerprinting now uses SHA-1 instead of MD5 since the latter tends to be slower and less widely supported these days. (Github issue :issue:
2790
)π The long deprecated include files
python_*
,stdio
,stdlib
andstl
inCython/Includes/Deprecated/
were removed. Use thelibc.*
andcpython.*
pxd modules instead. Patch by Jeroen Demeyer. (Github issue :issue:2904
)The search order for include files was changed. Previously it was
include_directories
,Cython/Includes
,sys.path
. Now it isinclude_directories
,sys.path
,Cython/Includes
. This was done to allow third-party*.pxd
files to override the ones in Cython. Patch by Matti Picus. (Github issue :issue:2905
)π The command line parser was rewritten and modernised using
argparse
. Patch by Egor Dranischnikow. (Github issue :issue:2952
, :issue:3001
)π Dotted filenames for qualified module names (
pkg.mod.pyx
) are deprecated. Use the normal Python package directory layout instead. (Github issue :issue:2686
)π§ Binary Linux wheels now follow the manylinux2010 standard. Patch by Alexey Stepanov. (Github issue :issue:
3355
)π Support for Python 2.6 was removed.
.. _
PEP-560
: https://www.python.org/dev/peps/pep-0560 .. _PEP-570
: https://www.python.org/dev/peps/pep-0570 .. _PEP-487
: https://www.python.org/dev/peps/pep-0487 .. _PEP-590
: https://www.python.org/dev/peps/pep-0590 .. _PEP-3131
: https://www.python.org/dev/peps/pep-3131 .. _PEP-563
: https://www.python.org/dev/peps/pep-0563 .. _PEP-479
: https://www.python.org/dev/peps/pep-0479.. _0.29.24:
Previous changes from v0.29.16
-
π Bugs fixed
Temporary internal variables in nested prange loops could leak into other threads. Patch by Frank Schlimbach. (Github issue :issue:
3348
)0οΈβ£ Default arguments on fused functions could crash. Patch by David Woods. (Github issue :issue:
3370
)C-tuples declared in
.pxd
files could generate incomplete C code. Patch by Kirk Meyer. (Github issue :issue:1427
)Fused functions were not always detected and optimised as Cython implemented functions. Patch by David Woods. (Github issue :issue:
3384
)Valid Python object concatenation of (iterable) strings to non-strings could fail with an exception. Patch by David Woods. (Github issue :issue:
3433
)Using C functions as temporary values lead to invalid C code. Original patch by David Woods. (Github issue :issue:
3418
)π Fix an unhandled C++ exception in comparisons. Patch by David Woods. (Github issue :issue:
3361
)π Fix deprecated import of "imp" module. Patch by Matti Picus. (Github issue :issue:
3350
)π Fix compatibility with Pythran 0.9.6 and later. Patch by Serge Guelton. (Github issue :issue:
3308
)The
_Py_PyAtExit()
function incpython.pylifecycle
was misdeclared. Patch by Zackery Spytz. (Github issue :issue:3382
)Several missing declarations in
cpython.*
were added. Patches by Zackery Spytz. (Github issue :issue:3452
, :issue:3421
, :issue:3411
, :issue:3402
)A declaration for
libc.math.fpclassify()
was added. Patch by Zackery Spytz. (Github issue :issue:2514
)β Avoid "undeclared" warning about automatically generated pickle methods. Patch by David Woods. (Github issue :issue:
3353
)β Avoid C compiler warning about unreachable code in
prange()
.β Some C compiler warnings in PyPy were resolved. Patch by Matti Picus. (Github issue :issue:
3437
)
.. _0.29.15: