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Python News

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What's New in Python 3.5 alpha 1?

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

Release date: TBA

Core and Builtins

-----------------

- Issue #22847: Improve method cache efficiency.

- Issue #22335: Fix crash when trying to enlarge a bytearray to 0x7fffffff

bytes on a 32-bit platform.

- Issue #22653: Fix an assertion failure in debug mode when doing a reentrant

dict insertion in debug mode.

- Issue #22643: Fix integer overflow in Unicode case operations (upper, lower,

title, swapcase, casefold).

- Issue #17636: Circular imports involving relative imports are now

supported.

- Issue #22604: Fix assertion error in debug mode when dividing a complex

number by (nan+0j).

- Issue #21052: Do not raise ImportWarning when sys.path_hooks or sys.meta_path

are set to None.

- Issue #16518: Use 'bytes-like object required' in error messages that

previously used the far more cryptic "'x' does not support the buffer

protocol.

- Issue #22470: Fixed integer overflow issues in "backslashreplace",

"xmlcharrefreplace", and "surrogatepass" error handlers.

- Issue #22540: speed up `PyObject_IsInstance` and `PyObject_IsSubclass` in the

common case that the second argument has metaclass `type`.

- Issue #18711: Add a new `PyErr_FormatV` function, similar to `PyErr_Format`

but accepting a `va_list` argument.

- Issue #22520: Fix overflow checking when generating the repr of a unicode

object.

- Issue #22519: Fix overflow checking in PyBytes_Repr.

- Issue #22518: Fix integer overflow issues in latin-1 encoding.

- Issue #16324: _charset parameter of MIMEText now also accepts

email.charset.Charset instances. Initial patch by Claude Paroz.

- Issue #1764286: Fix inspect.getsource() to support decorated functions.

Patch by Claudiu Popa.

- Issue #18554: os.__all__ includes posix functions.

- Issue #21391: Use os.path.abspath in the shutil module.

- Issue #11471: avoid generating a JUMP_FORWARD instruction at the end of

an if-block if there is no else-clause. Original patch by Eugene Toder.

- Issue #22215: Now ValueError is raised instead of TypeError when str or bytes

argument contains not permitted null character or byte.

- Issue #22258: Fix the internal function set_inheritable() on Illumos.

This platform exposes the function ``ioctl(FIOCLEX)``, but calling it fails

with errno is ENOTTY: "Inappropriate ioctl for device". set_inheritable()

now falls back to the slower ``fcntl()`` (``F_GETFD`` and then ``F_SETFD``).

- Issue #21389: Displaying the __qualname__ of the underlying function in the

repr of a bound method.

- Issue #22206: Using pthread, PyThread_create_key() now sets errno to ENOMEM

and returns -1 (error) on integer overflow.

- Issue #20184: Argument Clinic based signature introspection added for

30 of the builtin functions.

- Issue #22116: C functions and methods (of the 'builtin_function_or_method'

type) can now be weakref'ed. Patch by Wei Wu.

- Issue #22077: Improve index error messages for bytearrays, bytes, lists,

and tuples by adding 'or slices'. Added ', not <typename' for bytearrays.

Original patch by Claudiu Popa.

- Issue #20179: Apply Argument Clinic to bytes and bytearray.

Patch by Tal Einat.

- Issue #22082: Clear interned strings in slotdefs.

- Upgrade Unicode database to Unicode 7.0.0.

- Issue #21897: Fix a crash with the f_locals attribute with closure

variables when frame.clear() has been called.

- Issue #21205: Add a new ``__qualname__`` attribute to generator, the

qualified name, and use it in the representation of a generator

(``repr(gen)``). The default name of the generator (``__name__`` attribute)

is now get from the function instead of the code. Use ``gen.gi_code.co_name``

to get the name of the code.

- Issue #21669: With the aid of heuristics in SyntaxError.__init__, the

parser now attempts to generate more meaningful (or at least more search

engine friendly) error messages when "exec" and "print" are used as

statements.

- Issue #21642: If the conditional if-else expression, allow an integer written

with no space between itself and the ``else`` keyword (e.g. ``True if 42else

False``) to be valid syntax.

- Issue #21523: Fix over-pessimistic computation of the stack effect of

some opcodes in the compiler. This also fixes a quadratic compilation

time issue noticeable when compiling code with a large number of "and"

and "or" operators.

- Issue #21418: Fix a crash in the builtin function super() when called without

argument and without current frame (ex: embedded Python).

- Issue #21425: Fix flushing of standard streams in the interactive

interpreter.

- Issue #21435: In rare cases, when running finalizers on objects in cyclic

trash a bad pointer dereference could occur due to a subtle flaw in

internal iteration logic.

- Issue #21377: PyBytes_Concat() now tries to concatenate in-place when the

first argument has a reference count of 1. Patch by Nikolaus Rath.

- Issue #20355: -W command line options now have higher priority than the

PYTHONWARNINGS environment variable. Patch by Arfrever.

- Issue #21274: Define PATH_MAX for GNU/Hurd in Python/pythonrun.c.

- Issue #20904: Support setting FPU precision on m68k.

- Issue #21209: Fix sending tuples to custom generator objects with the yield

from syntax.

- Issue #21193: pow(a, b, c) now raises ValueError rather than TypeError when b

is negative. Patch by Josh Rosenberg.

- PEP 465 and Issue #21176: Add the '@' operator for matrix multiplication.

- Issue #21134: Fix segfault when str is called on an uninitialized

UnicodeEncodeError, UnicodeDecodeError, or UnicodeTranslateError object.

- Issue #19537: Fix PyUnicode_DATA() alignment under m68k. Patch by

Andreas Schwab.

- Issue #20929: Add a type cast to avoid shifting a negative number.

- Issue #20731: Properly position in source code files even if they

are opened in text mode. Patch by Serhiy Storchaka.

- Issue #20637: Key-sharing now also works for instance dictionaries of

subclasses. Patch by Peter Ingebretson.

- Issue #8297: Attributes missing from modules now include the module name

in the error text. Original patch by ysj.ray.

- Issue #19995: %c, %o, %x, and %X now raise TypeError on non-integer input.

- Issue #19655: The ASDL parser - used by the build process to generate code for

managing the Python AST in C - was rewritten. The new parser is self contained

and does not require to carry long the spark.py parser-generator library;

spark.py was removed from the source base.

- Issue #12546: Allow \x00 to be used as a fill character when using str, int,

float, and complex __format__ methods.

- Issue #20480: Add ipaddress.reverse_pointer. Patch by Leon Weber.

- Issue #13598: Modify string.Formatter to support auto-numbering of

replacement fields. It now matches the behavior of str.format() in

this regard. Patches by Phil Elson and Ramchandra Apte.

- Issue #8931: Make alternate formatting ('#') for type 'c' raise an

exception. In versions prior to 3.5, '#' with 'c' had no effect. Now

specifying it is an error. Patch by Torsten Landschoff.

Library

-------

- Issue #22841: Reject coroutines in asyncio add_signal_handler().

Patch by Ludovic.Gasc.

- Issue #19494: Added urllib.request.HTTPBasicPriorAuthHandler. Patch by

Matej Cepl.

- Issue #22578: Added attributes to the re.error class.

- Issue #22849: Fix possible double free in the io.TextIOWrapper constructor.

- Issue #12728: Different Unicode characters having the same uppercase but

different lowercase are now matched in case-insensitive regular expressions.

- Issue #22821: Fixed fcntl() with integer argument on 64-bit big-endian

platforms.

- Issue #21650: Add an `--sort-keys` option to json.tool CLI.

- Issues #814253, #9179: Group references and conditional group references now

work in lookbehind assertions in regular expressions.

- Issue #22824: Updated reprlib output format for sets to use set literals.

Patch contributed by Berker Peksag.

- Issue #22406: Fixed the uu_codec codec incorrectly ported to 3.x.

Based on patch by Martin Panter.

- Issue #17293: uuid.getnode() now determines MAC address on AIX using netstat.

Based on patch by Aivars Kalvāns.

- Issue #22769: Fixed ttk.Treeview.tag_has() when called without arguments.

- Issue #22417: Verify certificates by default in httplib (PEP 476).

- Issue #22775: Fixed unpickling of http.cookies.SimpleCookie with protocol 2

and above. Patch by Tim Graham.

- Issue #22776: Brought excluded code into the scope of a try block in

SysLogHandler.emit().

- Issue #22665: Add missing get_terminal_size and SameFileError to

shutil.__all__.

- Issue #6623: Remove deprecated Netrc class in the ftplib module. Patch by

Matt Chaput.

- Issue #17381: Fixed handling of case-insensitive ranges in regular

expressions.

- Issue #22410: Module level functions in the re module now cache compiled

locale-dependent regular expressions taking into account the locale.

- Issue #22759: Query methods on pathlib.Path() (exists(), is_dir(), etc.)

now return False when the underlying stat call raises NotADirectoryError.

- Issue #8876: distutils now falls back to copying files when hard linking

doesn't work. This allows use with special filesystems such as VirtualBox

shared folders.

- Issue #22217: Implemented reprs of classes in the zipfile module.

- Issue #22457: Honour load_tests in the start_dir of discovery.

- Issue #18216: gettext now raises an error when a .mo file has an

unsupported major version number. Patch by Aaron Hill.

- Issue #13918: Provide a locale.delocalize() function which can remove

locale-specific number formatting from a string representing a number,

without then converting it to a specific type. Patch by Cédric Krier.

- Issue #22676: Make the pickling of global objects which don't have a

__module__ attribute less slow.

- Issue #18853: Fixed ResourceWarning in shlex.__nain__.

- Issue #9351: Defaults set with set_defaults on an argparse subparser

are no longer ignored when also set on the parent parser.

- Issue #7559: unittest test loading ImportErrors are reported as import errors

with their import exception rather than as attribute errors after the import

has already failed.

- Issue #19746: Make it possible to examine the errors from unittest

discovery without executing the test suite. The new `errors` attribute

on TestLoader exposes these non-fatal errors encountered during discovery.

- Issue #21991: Make email.headerregistry's header 'params' attributes

be read-only (MappingProxyType). Previously the dictionary was modifiable

but a new one was created on each access of the attribute.

- Issue #22638: SSLv3 is now disabled throughout the standard library.

It can still be enabled by instantiating a SSLContext manually.

- Issue #22641: In asyncio, the default SSL context for client connections

is now created using ssl.create_default_context(), for stronger security.

- Issue #17401: Include closefd in io.FileIO repr.

- Issue #21338: Add silent mode for compileall. quiet parameters of

compile_{dir, file, path} functions now have a multilevel value. Also,

-q option of the CLI now have a multilevel value. Patch by Thomas Kluyver.

- Issue #20152: Convert the array and cmath modules to Argument Clinic.

- Issue #18643: Add socket.socketpair() on Windows.

- Issue #22435: Fix a file descriptor leak when SocketServer bind fails.

- Issue #13096: Fixed segfault in CTypes POINTER handling of large

values.

- Issue #11694: Raise ConversionError in xdrlib as documented. Patch

by Filip Gruszczyński and Claudiu Popa.

- Issue #19380: Optimized parsing of regular expressions.

- Issue #1519638: Now unmatched groups are replaced with empty strings in re.sub()

and re.subn().

- Issue #18615: sndhdr.what/whathdr now return a namedtuple.

- Issue #22462: Fix pyexpat's creation of a dummy frame to make it

appear in exception tracebacks.

- Issue #21965: Add support for in-memory SSL to the ssl module. Patch

by Geert Jansen.

- Issue #21173: Fix len() on a WeakKeyDictionary when .clear() was called

with an iterator alive.

- Issue #11866: Eliminated race condition in the computation of names

for new threads.

- Issue #21905: Avoid RuntimeError in pickle.whichmodule() when sys.modules

is mutated while iterating. Patch by Olivier Grisel.

- Issue #11271: concurrent.futures.Executor.map() now takes a *chunksize*

argument to allow batching of tasks in child processes and improve

performance of ProcessPoolExecutor. Patch by Dan O'Reilly.

- Issue #21883: os.path.join() and os.path.relpath() now raise a TypeError with

more helpful error message for unsupported or mismatched types of arguments.

- Issue #22219: The zipfile module CLI now adds entries for directories

(including empty directories) in ZIP file.

- Issue #22449: In the ssl.SSLContext.load_default_certs, consult the

enviromental variables SSL_CERT_DIR and SSL_CERT_FILE on Windows.

- Issue #22508: The email.__version__ variable has been removed; the email

code is no longer shipped separately from the stdlib, and __version__

hasn't been updated in several releases.

- Issue #20076: Added non derived UTF-8 aliases to locale aliases table.

- Issue #20079: Added locales supported in glibc 2.18 to locale alias table.

- Issue #20218: Added convenience methods read_text/write_text and read_bytes/

write_bytes to pathlib.Path objects.

- Issue #22437: Number of capturing groups in regular expression is no longer

limited by 100.

- Issue #17442: InteractiveInterpreter now displays the full chained traceback

in its showtraceback method, to match the built in interactive interpreter.

- Issue #10510: distutils register and upload methods now use HTML standards

compliant CRLF line endings.

- Issue #9850: Fixed macpath.join() for empty first component. Patch by

Oleg Oshmyan.

- Issue #5309: distutils' build and build_ext commands now accept a ``-j``

option to enable parallel building of extension modules.

- Issue #22448: Improve canceled timer handles cleanup to prevent

unbound memory usage. Patch by Joshua Moore-Oliva.

- Issue #22427: TemporaryDirectory no longer attempts to clean up twice when

used in the with statement in generator.

- Issue #22362: Forbidden ambiguous octal escapes out of range 0-0o377 in

regular expressions.

- Issue #20912: Now directories added to ZIP file have correct Unix and MS-DOS

directory attributes.

- Issue #21866: ZipFile.close() no longer writes ZIP64 central directory

records if allowZip64 is false.

- Issue #22278: Fix urljoin problem with relative urls, a regression observed

after changes to issue22118 were submitted.

- Issue #22415: Fixed debugging output of the GROUPREF_EXISTS opcode in the re

module. Removed trailing spaces in debugging output.

- Issue #22423: Unhandled exception in thread no longer causes unhandled

AttributeError when sys.stderr is None.

- Issue #21332: Ensure that ``bufsize=1`` in subprocess.Popen() selects

line buffering, rather than block buffering. Patch by Akira Li.

- Issue #21091: Fix API bug: email.message.EmailMessage.is_attachment is now

a method.

- Issue #21079: Fix email.message.EmailMessage.is_attachment to return the

correct result when the header has parameters as well as a value.

- Issue #22247: Add NNTPError to nntplib.__all__.

- Issue #22366: urllib.request.urlopen will accept a context object

(SSLContext) as an argument which will then used be for HTTPS connection.

Patch by Alex Gaynor.

- Issue #4180: The warnings registries are now reset when the filters

are modified.

- Issue #22419: Limit the length of incoming HTTP request in wsgiref server to

65536 bytes and send a 414 error code for higher lengths. Patch contributed

by Devin Cook.

- Lax cookie parsing in http.cookies could be a security issue when combined

with non-standard cookie handling in some Web browsers. Reported by

Sergey Bobrov.

- Issue #20537: logging methods now accept an exception instance as well as a

Boolean value or exception tuple. Thanks to Yury Selivanov for the patch.

- Issue #22384: An exception in Tkinter callback no longer crashes the program

when it is run with pythonw.exe.

- Issue #22168: Prevent turtle AttributeError with non-default Canvas on OS X.

- Issue #21147: sqlite3 now raises an exception if the request contains a null

character instead of truncate it. Based on patch by Victor Stinner.

- Issue #13968: The glob module now supports recursive search in

subdirectories using the "**" pattern.

- Issue #21951: Fixed a crash in Tkinter on AIX when called Tcl command with

empty string or tuple argument.

- Issue #21951: Tkinter now most likely raises MemoryError instead of crash

if the memory allocation fails.

- Issue #22338: Fix a crash in the json module on memory allocation failure.

- Issue #12410: imaplib.IMAP4 now supports the context management protocol.

Original patch by Tarek Ziadé.

- Issue #21270: We now override tuple methods in mock.call objects so that

they can be used as normal call attributes.

- Issue #16662: load_tests() is now unconditionally run when it is present in

a package's __init__.py. TestLoader.loadTestsFromModule() still accepts

use_load_tests, but it is deprecated and ignored. A new keyword-only

attribute `pattern` is added and documented. Patch given by Robert Collins,

tweaked by Barry Warsaw.

- Issue #22226: First letter no longer is stripped from the "status" key in

the result of Treeview.heading().

- Issue #19524: Fixed resource leak in the HTTP connection when an invalid

response is received. Patch by Martin Panter.

- Issue #20421: Add a .version() method to SSL sockets exposing the actual

protocol version in use.

- Issue #19546: configparser exceptions no longer expose implementation details.

Chained KeyErrors are removed, which leads to cleaner tracebacks. Patch by

Claudiu Popa.

- Issue #22051: turtledemo no longer reloads examples to re-run them.

Initialization of variables and gui setup should be done in main(),

which is called each time a demo is run, but not on import.

- Issue #21933: Turtledemo users can change the code font size with a menu

selection or control(command) '-' or '+' or control-mousewheel.

Original patch by Lita Cho.

- Issue #21597: The separator between the turtledemo text pane and the drawing

canvas can now be grabbed and dragged with a mouse. The code text pane can

be widened to easily view or copy the full width of the text. The canvas

can be widened on small screens. Original patches by Jan Kanis and Lita Cho.

- Issue #18132: Turtledemo buttons no longer disappear when the window is

shrunk. Original patches by Jan Kanis and Lita Cho.

- Issue #22043: time.monotonic() is now always available.

``threading.Lock.acquire()``, ``threading.RLock.acquire()`` and socket

operations now use a monotonic clock, instead of the system clock, when a

timeout is used.

- Issue #21527: Add a default number of workers to ThreadPoolExecutor equal

to 5 times the number of CPUs. Patch by Claudiu Popa.

- Issue #22216: smtplib now resets its state more completely after a quit. The

most obvious consequence of the previous behavior was a STARTTLS failure

during a connect/starttls/quit/connect/starttls sequence.

- Issue #22098: ctypes' BigEndianStructure and LittleEndianStructure now

define an empty __slots__ so that subclasses don't always get an instance

dict. Patch by Claudiu Popa.

- Issue #22185: Fix an occasional RuntimeError in threading.Condition.wait()

caused by mutation of the waiters queue without holding the lock. Patch

by Doug Zongker.

- Issue #22287: On UNIX, _PyTime_gettimeofday() now uses

clock_gettime(CLOCK_REALTIME) if available. As a side effect, Python now

depends on the librt library on Solaris and on Linux (only with glibc older

than 2.17).

- Issue #22182: Use e.args to unpack exceptions correctly in

distutils.file_util.move_file. Patch by Claudiu Popa.

- The webbrowser module now uses subprocess's start_new_session=True rather

than a potentially risky preexec_fn=os.setsid call.

- Issue #22042: signal.set_wakeup_fd(fd) now raises an exception if the file

descriptor is in blocking mode.

- Issue #16808: inspect.stack() now returns a named tuple instead of a tuple.

Patch by Daniel Shahaf.

- Issue #22236: Fixed Tkinter images copying operations in NoDefaultRoot mode.

- Issue #2527: Add a *globals* argument to timeit functions, in order to

override the globals namespace in which the timed code is executed.

Patch by Ben Roberts.

- Issue #22118: Switch urllib.parse to use RFC 3986 semantics for the

resolution of relative URLs, rather than RFCs 1808 and 2396.

Patch by Demian Brecht.

- Issue #21549: Added the "members" parameter to TarFile.list().

- Issue #19628: Allow compileall recursion depth to be specified with a -r

option.

- Issue #15696: Add a __sizeof__ implementation for mmap objects on Windows.

- Issue #22068: Avoided reference loops with Variables and Fonts in Tkinter.

- Issue #22165: SimpleHTTPRequestHandler now supports undecodable file names.

- Issue #15381: Optimized line reading in io.BytesIO.

- Issue #8797: Raise HTTPError on failed Basic Authentication immediately.

Initial patch by Sam Bull.

- Issue #20729: Restored the use of lazy iterkeys()/itervalues()/iteritems()

in the mailbox module.

- Issue #21448: Changed FeedParser feed() to avoid O(N**2) behavior when

parsing long line. Original patch by Raymond Hettinger.

- Issue #22184: The functools LRU Cache decorator factory now gives an earlier

and clearer error message when the user forgets the required parameters.

- Issue #17923: glob() patterns ending with a slash no longer match non-dirs on

AIX. Based on patch by Delhallt.

- Issue #21725: Added support for RFC 6531 (SMTPUTF8) in smtpd.

- Issue #22176: Update the ctypes module's libffi to v3.1. This release

adds support for the Linux AArch64 and POWERPC ELF ABIv2 little endian

architectures.

- Issue #5411: Added support for the "xztar" format in the shutil module.

- Issue #21121: Don't force 3rd party C extensions to be built with

-Werror=declaration-after-statement.

- Issue #21975: Fixed crash when using uninitialized sqlite3.Row (in particular

when unpickling pickled sqlite3.Row). sqlite3.Row is now initialized in the

__new__() method.

- Issue #20170: Convert posixmodule to use Argument Clinic.

- Issue #21539: Add a *exists_ok* argument to `Pathlib.mkdir()` to mimic

`mkdir -p` and `os.makedirs()` functionality. When true, ignore

FileExistsErrors. Patch by Berker Peksag.

- Issue #22127: Bypass IDNA for pure-ASCII host names in the socket module

(in particular for numeric IPs).

- Issue #21047: set the default value for the *convert_charrefs* argument

of HTMLParser to True. Patch by Berker Peksag.

- Add an __all__ to html.entities.

- Issue #15114: the strict mode and argument of HTMLParser, HTMLParser.error,

and the HTMLParserError exception have been removed.

- Issue #22085: Dropped support of Tk 8.3 in Tkinter.

- Issue #21580: Now Tkinter correctly handles bytes arguments passed to Tk.

In particular this allows to initialize images from binary data.

- Issue #22003: When initialized from a bytes object, io.BytesIO() now

defers making a copy until it is mutated, improving performance and

memory use on some use cases. Patch by David Wilson.

- Issue #22018: On Windows, signal.set_wakeup_fd() now also supports sockets.

A side effect is that Python depends to the WinSock library.

- Issue #22054: Add os.get_blocking() and os.set_blocking() functions to get

and set the blocking mode of a file descriptor (False if the O_NONBLOCK flag

is set, True otherwise). These functions are not available on Windows.

- Issue #17172: Make turtledemo start as active on OS X even when run with

subprocess. Patch by Lita Cho.

- Issue #21704: Fix build error for _multiprocessing when semaphores

are not available. Patch by Arfrever Frehtes Taifersar Arahesis.

- Issue #20173: Convert sha1, sha256, sha512 and md5 to ArgumentClinic.

Patch by Vajrasky Kok.

- Fix repr(_socket.socket) on Windows 64-bit: don't fail with OverflowError

on closed socket. repr(socket.socket) already works fine.

- Issue #22033: Reprs of most Python implemened classes now contain actual

class name instead of hardcoded one.

- Issue #21947: The dis module can now disassemble generator-iterator

objects based on their gi_code attribute. Patch by Clement Rouault.

- Issue #16133: The asynchat.async_chat.handle_read() method now ignores

BlockingIOError exceptions.

- Issue #22044: Fixed premature DECREF in call_tzinfo_method.

Patch by Tom Flanagan.

- Issue #19884: readline: Disable the meta modifier key if stdout is not

a terminal to not write the ANSI sequence "\033[1034h" into stdout. This

sequence is used on some terminal (ex: TERM=xterm-256color") to enable

support of 8 bit characters.

- Issue #4350: Removed a number of out-of-dated and non-working for a long time

Tkinter methods.

- Issue #6167: Scrollbar.activate() now returns the name of active element if

the argument is not specified. Scrollbar.set() now always accepts only 2

arguments.

- Issue #15275: Clean up and speed up the ntpath module.

- Issue #21888: plistlib's load() and loads() now work if the fmt parameter is

specified.

- Issue #22032: __qualname__ instead of __name__ is now always used to format

fully qualified class names of Python implemented classes.

- Issue #22031: Reprs now always use hexadecimal format with the "0x" prefix

when contain an id in form " at 0x...".

- Issue #22018: signal.set_wakeup_fd() now raises an OSError instead of a

ValueError on ``fstat()`` failure.

- Issue #21044: tarfile.open() now handles fileobj with an integer 'name'

attribute. Based on patch by Antoine Pietri.

- Issue #21966: Respect -q command-line option when code module is ran.

- Issue #19076: Don't pass the redundant 'file' argument to self.error().

- Issue #16382: Improve exception message of warnings.warn() for bad

category. Initial patch by Phil Elson.

- Issue #21932: os.read() now uses a :c:func:`Py_ssize_t` type instead of

:c:type:`int` for the size to support reading more than 2 GB at once. On

Windows, the size is truncted to INT_MAX. As any call to os.read(), the OS

may read less bytes than the number of requested bytes.

- Issue #21942: Fixed source file viewing in pydoc's server mode on Windows.

- Issue #11259: asynchat.async_chat().set_terminator() now raises a ValueError

if the number of received bytes is negative.

- Issue #12523: asynchat.async_chat.push() now raises a TypeError if it doesn't

get a bytes string

- Issue #21707: Add missing kwonlyargcount argument to

ModuleFinder.replace_paths_in_code().

- Issue #20639: calling Path.with_suffix('') allows removing the suffix

again. Patch by July Tikhonov.

- Issue #21714: Disallow the construction of invalid paths using

Path.with_name(). Original patch by Antony Lee.

- Issue #15014: Added 'auth' method to smtplib to make implementing auth

mechanisms simpler, and used it internally in the login method.

- Issue #21151: Fixed a segfault in the winreg module when ``None`` is passed

as a ``REG_BINARY`` value to SetValueEx. Patch by John Ehresman.

- Issue #21090: io.FileIO.readall() does not ignore I/O errors anymore. Before,

it ignored I/O errors if at least the first C call read() succeed.

- Issue #5800: headers parameter of wsgiref.headers.Headers is now optional.

Initial patch by Pablo Torres Navarrete and SilentGhost.

- Issue #21781: ssl.RAND_add() now supports strings longer than 2 GB.

- Issue #21679: Prevent extraneous fstat() calls during open(). Patch by

Bohuslav Kabrda.

- Issue #21863: cProfile now displays the module name of C extension functions,

in addition to their own name.

- Issue #11453: asyncore: emit a ResourceWarning when an unclosed file_wrapper

object is destroyed. The destructor now closes the file if needed. The

close() method can now be called twice: the second call does nothing.

- Issue #21858: Better handling of Python exceptions in the sqlite3 module.

- Issue #21476: Make sure the email.parser.BytesParser TextIOWrapper is

discarded after parsing, so the input file isn't unexpectedly closed.

- Issue #20295: imghdr now recognizes OpenEXR format images.

- Issue #21729: Used the "with" statement in the dbm.dumb module to ensure

files closing. Patch by Claudiu Popa.

- Issue #21491: socketserver: Fix a race condition in child processes reaping.

- Issue #21719: Added the ``st_file_attributes`` field to os.stat_result on

Windows.

- Issue #21832: Require named tuple inputs to be exact strings.

- Issue #21722: The distutils "upload" command now exits with a non-zero

return code when uploading fails. Patch by Martin Dengler.

- Issue #21723: asyncio.Queue: support any type of number (ex: float) for the

maximum size. Patch written by Vajrasky Kok.

- Issue #21711: support for "site-python" directories has now been removed

from the site module (it was deprecated in 3.4).

- Issue #17552: new socket.sendfile() method allowing to send a file over a

socket by using high-performance os.sendfile() on UNIX.

Patch by Giampaolo Rodola'.

- Issue #18039: dbm.dump.open() now always creates a new database when the

flag has the value 'n'. Patch by Claudiu Popa.

- Issue #21326: Add a new is_closed() method to asyncio.BaseEventLoop.

run_forever() and run_until_complete() methods of asyncio.BaseEventLoop now

raise an exception if the event loop was closed.

- Issue #21766: Prevent a security hole in CGIHTTPServer by URL unquoting paths

before checking for a CGI script at that path.

- Issue #21310: Fixed possible resource leak in failed open().

- Issue #21256: Printout of keyword args should be in deterministic order in

a mock function call. This will help to write better doctests.

- Issue #21677: Fixed chaining nonnormalized exceptions in io close() methods.

- Issue #11709: Fix the pydoc.help function to not fail when sys.stdin is not a

valid file.

- Issue #21515: tempfile.TemporaryFile now uses os.O_TMPFILE flag is available.

- Issue #13223: Fix pydoc.writedoc so that the HTML documentation for methods

that use 'self' in the example code is generated correctly.

- Issue #21463: In urllib.request, fix pruning of the FTP cache.

- Issue #21618: The subprocess module could fail to close open fds that were

inherited by the calling process and already higher than POSIX resource

limits would otherwise allow. On systems with a functioning /proc/self/fd

or /dev/fd interface the max is now ignored and all fds are closed.

- Issue #20383: Introduce importlib.util.module_from_spec() as the preferred way

to create a new module.

- Issue #21552: Fixed possible integer overflow of too long string lengths in

the tkinter module on 64-bit platforms.

- Issue #14315: The zipfile module now ignores extra fields in the central

directory that are too short to be parsed instead of letting a struct.unpack

error bubble up as this "bad data" appears in many real world zip files in

the wild and is ignored by other zip tools.

- Issue #13742: Added "key" and "reverse" parameters to heapq.merge().

(First draft of patch contributed by Simon Sapin.)

- Issue #21402: tkinter.ttk now works when default root window is not set.

- Issue #3015: _tkinter.create() now creates tkapp object with wantobject=1 by

default.

- Issue #10203: sqlite3.Row now truly supports sequence protocol. In particulr

it supports reverse() and negative indices. Original patch by Claudiu Popa.

- Issue #18807: If copying (no symlinks) specified for a venv, then the python

interpreter aliases (python, python3) are now created by copying rather than

symlinking.

- Issue #20197: Added support for the WebP image type in the imghdr module.

Patch by Fabrice Aneche and Claudiu Popa.

- Issue #21513: Speedup some properties of IP addresses (IPv4Address,

IPv6Address) such as .is_private or .is_multicast.

- Issue #21137: Improve the repr for threading.Lock() and its variants

by showing the "locked" or "unlocked" status. Patch by Berker Peksag.

- Issue #21538: The plistlib module now supports loading of binary plist files

when reference or offset size is not a power of two.

- Issue #21455: Add a default backlog to socket.listen().

- Issue #21525: Most Tkinter methods which accepted tuples now accept lists too.

- Issue #22166: with the assistance of a new internal _codecs._forget_codec

helping function, test_codecs now clears the encoding caches to avoid the

appearance of a reference leak

- Issue #22236: Tkinter tests now don't reuse default root window. New root

window is created for every test class.

- Issue #10744: Fix PEP 3118 format strings on ctypes objects with a nontrivial

shape.

- Issue #20826: Optimize ipaddress.collapse_addresses().

- Issue #21487: Optimize ipaddress.summarize_address_range() and

ipaddress.{IPv4Network,IPv6Network}.subnets().

- Issue #21486: Optimize parsing of netmasks in ipaddress.IPv4Network and

ipaddress.IPv6Network.

- Issue #13916: Disallowed the surrogatepass error handler for non UTF-*

encodings.

- Issue #20998: Fixed re.fullmatch() of repeated single character pattern

with ignore case. Original patch by Matthew Barnett.

- Issue #21075: fileinput.FileInput now reads bytes from standard stream if

binary mode is specified. Patch by Sam Kimbrel.

- Issue #19775: Add a samefile() method to pathlib Path objects. Initial

patch by Vajrasky Kok.

- Issue #21226: Set up modules properly in PyImport_ExecCodeModuleObject

(and friends).

- Issue #21398: Fix an unicode error in the pydoc pager when the documentation

contains characters not encodable to the stdout encoding.

- Issue #16531: ipaddress.IPv4Network and ipaddress.IPv6Network now accept

an (address, netmask) tuple argument, so as to easily construct network

objects from existing addresses.

- Issue #21156: importlib.abc.InspectLoader.source_to_code() is now a

staticmethod.

- Issue #21424: Simplified and optimized heaqp.nlargest() and nmsmallest()

to make fewer tuple comparisons.

- Issue #21396: Fix TextIOWrapper(..., write_through=True) to not force a

flush() on the underlying binary stream. Patch by akira.

- Issue #18314: Unlink now removes junctions on Windows. Patch by Kim Gräsman

- Issue #21088: Bugfix for curses.window.addch() regression in 3.4.0.

In porting to Argument Clinic, the first two arguments were reversed.

- Issue #21407: _decimal: The module now supports function signatures.

- Issue #10650: Remove the non-standard 'watchexp' parameter from the

Decimal.quantize() method in the Python version. It had never been

present in the C version.

- Issue #21469: Reduced the risk of false positives in robotparser by

checking to make sure that robots.txt has been read or does not exist

prior to returning True in can_fetch().

- Issue #19414: Have the OrderedDict mark deleted links as unusable.

This gives an early failure if the link is deleted during iteration.

- Issue #21421: Add __slots__ to the MappingViews ABC.

Patch by Josh Rosenberg.

- Issue #21101: Eliminate double hashing in the C speed-up code for

collections.Counter().

- Issue #21321: itertools.islice() now releases the reference to the source

iterator when the slice is exhausted. Patch by Anton Afanasyev.

- Issue #21057: TextIOWrapper now allows the underlying binary stream's

read() or read1() method to return an arbitrary bytes-like object

(such as a memoryview). Patch by Nikolaus Rath.

- Issue #20951: SSLSocket.send() now raises either SSLWantReadError or

SSLWantWriteError on a non-blocking socket if the operation would block.

Previously, it would return 0. Patch by Nikolaus Rath.

- Issue #13248: removed previously deprecated asyncore.dispatcher __getattr__

cheap inheritance hack.

- Issue #9815: assertRaises now tries to clear references to local variables

in the exception's traceback.

- Issue #19940: ssl.cert_time_to_seconds() now interprets the given time

string in the UTC timezone (as specified in RFC 5280), not the local

timezone.

- Issue #13204: Calling sys.flags.__new__ would crash the interpreter,

now it raises a TypeError.

- Issue #19385: Make operations on a closed dbm.dumb database always raise the

same exception.

- Issue #21207: Detect when the os.urandom cached fd has been closed or

replaced, and open it anew.

- Issue #21291: subprocess's Popen.wait() is now thread safe so that

multiple threads may be calling wait() or poll() on a Popen instance

at the same time without losing the Popen.returncode value.

- Issue #21127: Path objects can now be instantiated from str subclass

instances (such as ``numpy.str_``).

- Issue #15002: urllib.response object to use _TemporaryFileWrapper (and

_TemporaryFileCloser) facility. Provides a better way to handle file

descriptor close. Patch contributed by Christian Theune.

- Issue #12220: mindom now raises a custom ValueError indicating it doesn't

support spaces in URIs instead of letting a 'split' ValueError bubble up.

- Issue #21068: The ssl.PROTOCOL* constants are now enum members.

- Issue #21276: posixmodule: Don't define USE_XATTRS on KFreeBSD and the Hurd.

- Issue #21262: New method assert_not_called for Mock.

It raises AssertionError if the mock has been called.

- Issue #21238: New keyword argument `unsafe` to Mock. It raises

`AttributeError` incase of an attribute startswith assert or assret.

- Issue #20896: ssl.get_server_certificate() now uses PROTOCOL_SSLv23, not

PROTOCOL_SSLv3, for maximum compatibility.

- Issue #21239: patch.stopall() didn't work deterministically when the same

name was patched more than once.

- Issue #21203: Updated fileConfig and dictConfig to remove inconsistencies.

Thanks to Jure Koren for the patch.

- Issue #21222: Passing name keyword argument to mock.create_autospec now

works.

- Issue #21197: Add lib64 -> lib symlink in venvs on 64-bit non-OS X POSIX.

- Issue #17498: Some SMTP servers disconnect after certain errors, violating

strict RFC conformance. Instead of losing the error code when we issue the

subsequent RSET, smtplib now returns the error code and defers raising the

SMTPServerDisconnected error until the next command is issued.

- Issue #17826: setting an iterable side_effect on a mock function created by

create_autospec now works. Patch by Kushal Das.

- Issue #7776: Fix ``Host:`` header and reconnection when using

http.client.HTTPConnection.set_tunnel(). Patch by Nikolaus Rath.

- Issue #20968: unittest.mock.MagicMock now supports division.

Patch by Johannes Baiter.

- Fix arbitrary memory access in JSONDecoder.raw_decode with a negative second

parameter. Bug reported by Guido Vranken.

- Issue #21169: getpass now handles non-ascii characters that the

input stream encoding cannot encode by re-encoding using the

replace error handler.

- Issue #21171: Fixed undocumented filter API of the rot13 codec.

Patch by Berker Peksag.

- Issue #20539: Improved math.factorial error message for large positive inputs

and changed exception type (OverflowError -> ValueError) for large negative

inputs.

- Issue #21172: isinstance check relaxed from dict to collections.Mapping.

- Issue #21155: asyncio.EventLoop.create_unix_server() now raises a ValueError

if path and sock are specified at the same time.

- Issue #21136: Avoid unnecessary normalization of Fractions resulting from

power and other operations. Patch by Raymond Hettinger.

- Issue #17621: Introduce importlib.util.LazyLoader.

- Issue #21076: signal module constants were turned into enums.

Patch by Giampaolo Rodola'.

- Issue #20636: Improved the repr of Tkinter widgets.

- Issue #19505: The items, keys, and values views of OrderedDict now support

reverse iteration using reversed().

- Issue #21149: Improved thread-safety in logging cleanup during interpreter

shutdown. Thanks to Devin Jeanpierre for the patch.

- Issue #21058: Fix a leak of file descriptor in

:func:`tempfile.NamedTemporaryFile`, close the file descriptor if