Python3.3有什么新变化

Z时代
2024-01-10
分类：综合

python lib

本文介绍了Python 3.3相比 3.2 的新增特性。Python 3.3于2012年9月29日发布。有关完整详细信息，请参见 changelog。

参见

PEP 398 - Python 3.3 发布计划

摘要 - 发布重点¶

新的语法特性：

New yieldfrom expression for generator delegation.

The u'unicode' syntax is accepted again for str objects.

新的库模块：

faulthandler （帮助调试低级崩溃）

ipaddress (high-level objects representing IP addresses and masks)

lzma (compress data using the XZ / LZMA algorithm)

unittest.mock (replace parts of your system under test with mock objects)

venv (Python virtual environments, as in the
popular virtualenv package)

新的内置特性：

重写 I/O 异常的层次结构.

实现的改进：

基于 importlib 重写 import machinery

More compact unicode strings.

More compact attribute dictionaries.

显着改进的库模块：

C Accelerator for the decimal module.

Better unicode handling in the email module
(provisional).

安全改进：

Hash randomization is switched on by default.

Please read on for a comprehensive list of user-facing changes.

PEP 405: 虚拟环境¶

Virtual environments help create separate Python setups while sharing a

system-wide base install, for ease of maintenance. Virtual environments

have their own set of private site packages (i.e. locally-installed

libraries), and are optionally segregated from the system-wide site

packages. Their concept and implementation are inspired by the popular

virtualenv third-party package, but benefit from tighter integration

with the interpreter core.

This PEP adds the venv module for programmatic access, and the

pyvenv script for command-line access and

administration. The Python interpreter checks for a pyvenv.cfg,

file whose existence signals the base of a virtual environment's directory

tree.

参见

PEP 405 - Python虚拟环境

PEP written by Carl Meyer; implementation by Carl Meyer and Vinay Sajip

PEP 420: 隐式命名空间包¶

Native support for package directories that don't require __init__.py

marker files and can automatically span multiple path segments (inspired by

various third party approaches to namespace packages, as described in

PEP 420)

参见

PEP 420 - 隐式命名空间包

PEP 由 Eric V. Smith 撰写，由 Eric V. Smith 和 Barry Warsaw 实现

PEP 3118: 新的内存视图实现和缓冲协议文档¶

The implementation of PEP 3118 has been significantly improved.

The new memoryview implementation comprehensively fixes all ownership and

lifetime issues of dynamically allocated fields in the Py_buffer struct

that led to multiple crash reports. Additionally, several functions that

crashed or returned incorrect results for non-contiguous or multi-dimensional

input have been fixed.

The memoryview object now has a PEP-3118 compliant getbufferproc()

that checks the consumer's request type. Many new features have been

added, most of them work in full generality for non-contiguous arrays

and arrays with suboffsets.

The documentation has been updated, clearly spelling out responsibilities

for both exporters and consumers. Buffer request flags are grouped into

basic and compound flags. The memory layout of non-contiguous and

multi-dimensional NumPy-style arrays is explained.

API changes¶

The maximum number of dimensions is officially limited to 64.

The representation of empty shape, strides and suboffsets is now
an empty tuple instead of None.

Accessing a memoryview element with format 'B' (unsigned bytes)
now returns an integer (in accordance with the struct module syntax).
For returning a bytes object the view must be cast to 'c' first.

memoryview comparisons now use the logical structure of the operands
and compare all array elements by value. All format strings in struct
module syntax are supported. Views with unrecognised format strings
are still permitted, but will always compare as unequal, regardless
of view contents.

For further changes see Build and C API Changes and Porting C code.

（由 Stefan Krah 在 bpo-10181 中贡献。）

参见

PEP 3118 - 修改缓冲区协议

PEP 393: 灵活的字符串表示¶

The Unicode string type is changed to support multiple internal

representations, depending on the character with the largest Unicode ordinal

(1, 2, or 4 bytes) in the represented string. This allows a space-efficient

representation in common cases, but gives access to full UCS-4 on all

systems. For compatibility with existing APIs, several representations may

exist in parallel; over time, this compatibility should be phased out.

On the Python side, there should be no downside to this change.

On the C API side, PEP 393 is fully backward compatible. The legacy API

should remain available at least five years. Applications using the legacy

API will not fully benefit of the memory reduction, or - worse - may use

a bit more memory, because Python may have to maintain two versions of each

string (in the legacy format and in the new efficient storage).

Functionality¶

Changes introduced by PEP 393 are the following:

Python now always supports the full range of Unicode code points, including
non-BMP ones (i.e. from U+0000 to U+10FFFF). The distinction between
narrow and wide builds no longer exists and Python now behaves like a wide
build, even under Windows.

With the death of narrow builds, the problems specific to narrow builds have
also been fixed, for example:
- len() now always returns 1 for non-BMP characters,
  so len('\U0010FFFF')==1;
- surrogate pairs are not recombined in string literals,
  so '\uDBFF\uDFFF'!='\U0010FFFF';
- indexing or slicing non-BMP characters returns the expected value,
  so '\U0010FFFF'[0] now returns '\U0010FFFF' and not '\uDBFF';
- all other functions in the standard library now correctly handle
  non-BMP code points.

The value of sys.maxunicode is now always 1114111 (0x10FFFF
in hexadecimal). The PyUnicode_GetMax() function still returns
either 0xFFFF or 0x10FFFF for backward compatibility, and it should
not be used with the new Unicode API (see bpo-13054).

The ./configure flag --with-wide-unicode has been removed.

Performance and resource usage¶

The storage of Unicode strings now depends on the highest code point in the string:

pure ASCII and Latin1 strings (U+0000-U+00FF) use 1 byte per code point;

BMP strings (U+0000-U+FFFF) use 2 bytes per code point;

non-BMP strings (U+10000-U+10FFFF) use 4 bytes per code point.

The net effect is that for most applications, memory usage of string

storage should decrease significantly - especially compared to former

wide unicode builds - as, in many cases, strings will be pure ASCII

even in international contexts (because many strings store non-human

language data, such as XML fragments, HTTP headers, JSON-encoded data,

etc.). We also hope that it will, for the same reasons, increase CPU

cache efficiency on non-trivial applications. The memory usage of

Python 3.3 is two to three times smaller than Python 3.2, and a little

bit better than Python 2.7, on a Django benchmark (see the PEP for

details).

参见

PEP 393 - 灵活的字符串表示

PEP written by Martin von Löwis; implementation by Torsten Becker

and Martin von Löwis.

python-launcher-for-windows">

PEP 397: 适用于Windows的Python启动器¶

The Python 3.3 Windows installer now includes a py launcher application

that can be used to launch Python applications in a version independent

fashion.

This launcher is invoked implicitly when double-clicking *.py files.

If only a single Python version is installed on the system, that version

will be used to run the file. If multiple versions are installed, the most

recent version is used by default, but this can be overridden by including

a Unix-style "shebang line" in the Python script.

The launcher can also be used explicitly from the command line as the py

application. Running py follows the same version selection rules as

implicitly launching scripts, but a more specific version can be selected

by passing appropriate arguments (such as -3 to request Python 3 when

Python 2 is also installed, or -2.6 to specifically request an earlier

Python version when a more recent version is installed).

In addition to the launcher, the Windows installer now includes an

option to add the newly installed Python to the system PATH. (Contributed

by Brian Curtin in bpo-3561.)

参见

PEP 397 - 适用于Windows的Python启动器

PEP written by Mark Hammond and Martin v. Löwis; implementation by

Vinay Sajip.

Launcher documentation: 适用于Windows的Python启动器

Installer PATH modification: 查找Python可执行文件

PEP 3151: 重写 OS 和 IO 异常的层次结构¶

The hierarchy of exceptions raised by operating system errors is now both

simplified and finer-grained.

You don't have to worry anymore about choosing the appropriate exception

type between OSError, IOError, EnvironmentError,

WindowsError, mmap.error, socket.error or

select.error. All these exception types are now only one:

OSError. The other names are kept as aliases for compatibility

reasons.

Also, it is now easier to catch a specific error condition. Instead of

inspecting the errno attribute (or args[0]) for a particular

constant from the errno module, you can catch the adequate

OSError subclass. The available subclasses are the following:

BlockingIOError

ChildProcessError

ConnectionError

FileExistsError

FileNotFoundError

InterruptedError

IsADirectoryError

NotADirectoryError

PermissionError

ProcessLookupError

TimeoutError

And the ConnectionError itself has finer-grained subclasses:

BrokenPipeError

ConnectionAbortedError

ConnectionRefusedError

ConnectionResetError

Thanks to the new exceptions, common usages of the errno can now be

avoided. For example, the following code written for Python 3.2:

fromerrnoimportENOENT,EACCES,EPERM
try:
withopen("document.txt")asf:
content=f.read()
exceptIOErroraserr:
iferr.errno==ENOENT:
print("document.txt file is missing")
eliferr.errnoin(EACCES,EPERM):
print("You are not allowed to read document.txt")
else:
raise

can now be written without the errno import and without manual

inspection of exception attributes:

try:
withopen("document.txt")asf:
content=f.read()
exceptFileNotFoundError:
print("document.txt file is missing")
exceptPermissionError:
print("You are not allowed to read document.txt")

参见

PEP 3151 - 重写 OS 和 IO 异常的层次结构

PEP 由 Antoine Pitrou 撰写并实现

PEP 380: 委托给子生成器的语法¶

PEP 380 adds the yieldfrom expression, allowing a generator to

delegate

part of its operations to another generator. This allows a section of code

containing yield to be factored out and placed in another generator.

Additionally, the subgenerator is allowed to return with a value, and the

value is made available to the delegating generator.

While designed primarily for use in delegating to a subgenerator, the yield

from expression actually allows delegation to arbitrary subiterators.

For simple iterators, yieldfromiterable is essentially just a shortened

form of foriteminiterable:yielditem:

>>> defg(x):
... yield fromrange(x,0,-1)
... yield fromrange(x)
...
>>> list(g(5))
[5, 4, 3, 2, 1, 0, 1, 2, 3, 4]

However, unlike an ordinary loop, yieldfrom allows subgenerators to

receive sent and thrown values directly from the calling scope, and

return a final value to the outer generator:

>>> defaccumulate():
... tally=0
... while1:
... next=yield
... ifnextisNone:
... returntally
... tally+=next
...
>>> defgather_tallies(tallies):
... while1:
... tally=yield fromaccumulate()
... tallies.append(tally)
...
>>> tallies=[]
>>> acc=gather_tallies(tallies)
>>> next(acc)# Ensure the accumulator is ready to accept values
>>> foriinrange(4):
... acc.send(i)
...
>>> acc.send(None)# Finish the first tally
>>> foriinrange(5):
... acc.send(i)
...
>>> acc.send(None)# Finish the second tally
>>> tallies
[6, 10]

The main principle driving this change is to allow even generators that are

designed to be used with the send and throw methods to be split into

multiple subgenerators as easily as a single large function can be split into

multiple subfunctions.

参见

PEP 380 - 委托给子生成器的语法

PEP 由 Greg Ewing 撰写，由 Greg Ewing 实现。由 Renaud Blanch，Ryan Kelly 和 Nick Coghlan 集成到3.3，由 Zbigniew Jędrzejewski-Szmek 和 Nick Coghlan 编写文档

PEP 409: 清除异常上下文¶

PEP 409 introduces new syntax that allows the display of the chained

exception context to be disabled. This allows cleaner error messages in

applications that convert between exception types:

>>> classD:
... def__init__(self,extra):
... self._extra_attributes=extra
... def__getattr__(self,attr):
... try:
... returnself._extra_attributes[attr]
... exceptKeyError:
... raiseAttributeError(attr)fromNone
...
>>> D({}).x
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "<stdin>", line 8, in __getattr__
AttributeError: x

Without the fromNone suffix to suppress the cause, the original

exception would be displayed by default:

>>> classC:
... def__init__(self,extra):
... self._extra_attributes=extra
... def__getattr__(self,attr):
... try:
... returnself._extra_attributes[attr]
... exceptKeyError:
... raiseAttributeError(attr)
...
>>> C({}).x
Traceback (most recent call last):
  File "<stdin>", line 6, in __getattr__
KeyError: 'x'
During handling of the above exception, another exception occurred:
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "<stdin>", line 8, in __getattr__
AttributeError: x

No debugging capability is lost, as the original exception context remains

available if needed (for example, if an intervening library has incorrectly

suppressed valuable underlying details):

>>> try:
... D({}).x
... exceptAttributeErrorasexc:
... print(repr(exc.__context__))
...
KeyError('x',)

参见

PEP 409 - 清除异常上下文

PEP 由 Ethan Furman 撰写，由 Ethan Furman 和 Nick Coghlan 实现。

PEP 414: 显式的Unicode文本¶

To ease the transition from Python 2 for Unicode aware Python applications

that make heavy use of Unicode literals, Python 3.3 once again supports the

"u" prefix for string literals. This prefix has no semantic significance

in Python 3, it is provided solely to reduce the number of purely mechanical

changes in migrating to Python 3, making it easier for developers to focus on

the more significant semantic changes (such as the stricter default

separation of binary and text data).

参见

PEP 414 - 显式的Unicode文本

PEP 由 Armin Ronacher 撰写

PEP 3155: 类和函数的限定名称¶

Functions and class objects have a new __qualname__ attribute representing

the "path" from the module top-level to their definition. For global functions

and classes, this is the same as __name__. For other functions and classes,

it provides better information about where they were actually defined, and

how they might be accessible from the global scope.

Example with (non-bound) methods:

>>> classC:
... defmeth(self):
... pass
>>> C.meth.__name__
'meth'
>>> C.meth.__qualname__
'C.meth'

Example with nested classes:

>>> classC:
... classD:
... defmeth(self):
... pass
...
>>> C.D.__name__
'D'
>>> C.D.__qualname__
'C.D'
>>> C.D.meth.__name__
'meth'
>>> C.D.meth.__qualname__
'C.D.meth'

Example with nested functions:

>>> defouter():
... definner():
... pass
... returninner
...
>>> outer().__name__
'inner'
>>> outer().__qualname__
'outer.<locals>.inner'

The string representation of those objects is also changed to include the

new, more precise information:

>>> str(C.D)
"<class '__main__.C.D'>"
>>> str(C.D.meth)
'<function C.D.meth at 0x7f46b9fe31e0>'

参见

PEP 3155 - 类和函数的限定名称

PEP 由 Antoine Pitrou 撰写并实现

PEP 362: 函数签名对象¶

A new function inspect.signature() makes introspection of python

callables easy and straightforward. A broad range of callables is supported:

python functions, decorated or not, classes, and functools.partial()

objects. New classes inspect.Signature, inspect.Parameter

and inspect.BoundArguments hold information about the call signatures,

such as, annotations, default values, parameters kinds, and bound arguments,

which considerably simplifies writing decorators and any code that validates

or amends calling signatures or arguments.

参见

PEP 362: - 函数签名对象

PEP 由 Brett Cannon，Yury Selivanov，Larry Hastings，Jiwon Seo 撰写，由 Yury Selivanov 实现

PEP 421: 添加 sys.implementation¶

A new attribute on the sys module exposes details specific to the

implementation of the currently running interpreter. The initial set of

attributes on sys.implementation are name, version,

hexversion, and cache_tag.

The intention of sys.implementation is to consolidate into one namespace

the implementation-specific data used by the standard library. This allows

different Python implementations to share a single standard library code base

much more easily. In its initial state, sys.implementation holds only a

small portion of the implementation-specific data. Over time that ratio will

shift in order to make the standard library more portable.

One example of improved standard library portability is cache_tag. As of

Python 3.3, sys.implementation.cache_tag is used by importlib to

support PEP 3147 compliance. Any Python implementation that uses

importlib for its built-in import system may use cache_tag to control

the caching behavior for modules.

SimpleNamespace¶

The implementation of sys.implementation also introduces a new type to

Python: types.SimpleNamespace. In contrast to a mapping-based

namespace, like dict, SimpleNamespace is attribute-based, like

object. However, unlike object, SimpleNamespace instances

are writable. This means that you can add, remove, and modify the namespace

through normal attribute access.

参见

PEP 421 - 添加 sys.implementation

PEP 由 Eric Snow 撰写并实现

Using importlib as the Implementation of Import¶

bpo-2377 - Replace __import__ w/ importlib.__import__

bpo-13959 - Re-implement parts of imp in pure Python

bpo-14605 - Make import machinery explicit

bpo-14646 - Require loaders set __loader__ and __package__

The __import__() function is now powered by importlib.__import__().

This work leads to the completion of "phase 2" of PEP 302. There are

multiple benefits to this change. First, it has allowed for more of the

machinery powering import to be exposed instead of being implicit and hidden

within the C code. It also provides a single implementation for all Python VMs

supporting Python 3.3 to use, helping to end any VM-specific deviations in

import semantics. And finally it eases the maintenance of import, allowing for

future growth to occur.

For the common user, there should be no visible change in semantics. For

those whose code currently manipulates import or calls import

programmatically, the code changes that might possibly be required are covered

in the Porting Python code section of this document.

New APIs¶

One of the large benefits of this work is the exposure of what goes into

making the import statement work. That means the various importers that were

once implicit are now fully exposed as part of the importlib package.

The abstract base classes defined in importlib.abc have been expanded

to properly delineate between meta path finders

and path entry finders by introducing

importlib.abc.MetaPathFinder and

importlib.abc.PathEntryFinder, respectively. The old ABC of

importlib.abc.Finder is now only provided for backwards-compatibility

and does not enforce any method requirements.

In terms of finders, importlib.machinery.FileFinder exposes the

mechanism used to search for source and bytecode files of a module. Previously

this class was an implicit member of sys.path_hooks.

For loaders, the new abstract base class importlib.abc.FileLoader helps

write a loader that uses the file system as the storage mechanism for a module's

code. The loader for source files

(importlib.machinery.SourceFileLoader), sourceless bytecode files

(importlib.machinery.SourcelessFileLoader), and extension modules

(importlib.machinery.ExtensionFileLoader) are now available for

direct use.

ImportError now has name and path attributes which are set when

there is relevant data to provide. The message for failed imports will also

provide the full name of the module now instead of just the tail end of the

module's name.

The importlib.invalidate_caches() function will now call the method with

the same name on all finders cached in sys.path_importer_cache to help

clean up any stored state as necessary.

Visible Changes¶

For potential required changes to code, see the Porting Python code

section.

Beyond the expanse of what importlib now exposes, there are other

visible changes to import. The biggest is that sys.meta_path and

sys.path_hooks now store all of the meta path finders and path entry

hooks used by import. Previously the finders were implicit and hidden within

the C code of import instead of being directly exposed. This means that one can

now easily remove or change the order of the various finders to fit one's needs.

Another change is that all modules have a __loader__ attribute, storing the

loader used to create the module. PEP 302 has been updated to make this

attribute mandatory for loaders to implement, so in the future once 3rd-party

loaders have been updated people will be able to rely on the existence of the

attribute. Until such time, though, import is setting the module post-load.

Loaders are also now expected to set the __package__ attribute from

PEP 366. Once again, import itself is already setting this on all loaders

from importlib and import itself is setting the attribute post-load.

None is now inserted into sys.path_importer_cache when no finder

can be found on sys.path_hooks. Since imp.NullImporter is not

directly exposed on sys.path_hooks it could no longer be relied upon to

always be available to use as a value representing no finder found.

All other changes relate to semantic changes which should be taken into

consideration when updating code for Python 3.3, and thus should be read about

in the Porting Python code section of this document.

(Implementation by Brett Cannon)

其他语言特性修改¶

对Python 语言核心进行的小改动：

Added support for Unicode name aliases and named sequences.
Both unicodedata.lookup() and '\N{...}' now resolve name aliases,
and unicodedata.lookup() resolves named sequences too.
（由 Ezio Melotti 在 bpo-12753 中贡献。）

Unicode database updated to UCD version 6.1.0

Equality comparisons on range() objects now return a result reflecting
the equality of the underlying sequences generated by those range objects.
(bpo-13201)

The count(), find(), rfind(), index() and rindex()
methods of bytes and bytearray objects now accept an
integer between 0 and 255 as their first argument.
（由 Petri Lehtinen 在 bpo-12170 中贡献。）

The rjust(), ljust(), and center() methods of bytes
and bytearray now accept a bytearray for the fill
argument. (Contributed by Petri Lehtinen in bpo-12380.)

New methods have been added to list and bytearray:
copy() and clear() (bpo-10516). Consequently,
MutableSequence now also defines a
clear() method (bpo-11388).

Raw bytes literals can now be written rb"..." as well as br"...".
（由 Antoine Pitrou 在 bpo-13748 中贡献。）

dict.setdefault() now does only one lookup for the given key, making
it atomic when used with built-in types.
（由 Filip Gruszczyński 在 bpo-13521 中贡献。）

The error messages produced when a function call does not match the function
signature have been significantly improved.
（由 Benjamin Peterson 贡献。）

A Finer-Grained Import Lock¶

Previous versions of CPython have always relied on a global import lock.

This led to unexpected annoyances, such as deadlocks when importing a module

would trigger code execution in a different thread as a side-effect.

Clumsy workarounds were sometimes employed, such as the

PyImport_ImportModuleNoBlock() C API function.

In Python 3.3, importing a module takes a per-module lock. This correctly

serializes importation of a given module from multiple threads (preventing

the exposure of incompletely initialized modules), while eliminating the

aforementioned annoyances.

（由 Antoine Pitrou 在 bpo-9260 中贡献。）

Builtin functions and types¶

open() gets a new opener parameter: the underlying file descriptor
for the file object is then obtained by calling opener with (file,
flags). It can be used to use custom flags like os.O_CLOEXEC for
example. The 'x' mode was added: open for exclusive creation, failing if
the file already exists.

print(): added the flush keyword argument. If the flush keyword
argument is true, the stream is forcibly flushed.

hash(): hash randomization is enabled by default, see
object.__hash__() and PYTHONHASHSEED.

The str type gets a new casefold() method: return a
casefolded copy of the string, casefolded strings may be used for caseless
matching. For example, 'ß'.casefold() returns 'ss'.

The sequence documentation has been substantially rewritten to better
explain the binary/text sequence distinction and to provide specific
documentation sections for the individual builtin sequence types
(bpo-4966).

新增模块¶

faulthandler¶

This new debug module faulthandler contains functions to dump Python tracebacks explicitly,

on a fault (a crash like a segmentation fault), after a timeout, or on a user

signal. Call faulthandler.enable() to install fault handlers for the

SIGSEGV, SIGFPE, SIGABRT, SIGBUS, and

SIGILL signals. You can also enable them at startup by setting the

PYTHONFAULTHANDLER environment variable or by using -X

faulthandler command line option.

Example of a segmentation fault on Linux:

$ python -q -X faulthandler
>>> import ctypes
>>> ctypes.string_at(0)
Fatal Python error: Segmentation fault
Current thread 0x00007fb899f39700:
  File "/home/python/cpython/Lib/ctypes/__init__.py", line 486 in string_at
  File "<stdin>", line 1 in <module>
Segmentation fault

ipaddress¶

The new ipaddress module provides tools for creating and manipulating

objects representing IPv4 and IPv6 addresses, networks and interfaces (i.e.

an IP address associated with a specific IP subnet).

（由 Google 和 Peter Moody 在 bpo-3144 中贡献。）

lzma¶

The newly-added lzma module provides data compression and decompression

using the LZMA algorithm, including support for the .xz and .lzma

file formats.

（由 Nadeem Vawda 和 Per Øyvind Karlsen 在 bpo-16531 中贡献。）

改进的模块¶

abc¶

Improved support for abstract base classes containing descriptors composed with

abstract methods. The recommended approach to declaring abstract descriptors is

now to provide __isabstractmethod__ as a dynamically updated

property. The built-in descriptors have been updated accordingly.

abc.abstractproperty has been deprecated, use property
with abc.abstractmethod() instead.
abc.abstractclassmethod has been deprecated, use
classmethod with abc.abstractmethod() instead.
abc.abstractstaticmethod has been deprecated, use
staticmethod with abc.abstractmethod() instead.

（由 Pablo Galindo 在 bpo-11610 中贡献。）

abc.ABCMeta.register() now returns the registered subclass, which means

it can now be used as a class decorator (bpo-10868).

array¶

The array module supports the longlong type using q and

Q type codes.

（由 Oren Tirosh 和 Hirokazu Yamamoto 在 bpo-1172711 中贡献。）

base64¶

ASCII-only Unicode strings are now accepted by the decoding functions of the

base64 modern interface. For example, base64.b64decode('YWJj')

returns b'abc'. (Contributed by Catalin Iacob in bpo-13641.)

binascii¶

In addition to the binary objects they normally accept, the a2b_ functions

now all also accept ASCII-only strings as input. (Contributed by Antoine

Pitrou in bpo-13637.)

bz2¶

The bz2 module has been rewritten from scratch. In the process, several

new features have been added:

New bz2.open() function: open a bzip2-compressed file in binary or
text mode.

bz2.BZ2File can now read from and write to arbitrary file-like
objects, by means of its constructor's fileobj argument.
（由 Nadeem Vawda 在 bpo-5863 中贡献。）

bz2.BZ2File and bz2.decompress() can now decompress
multi-stream inputs (such as those produced by the pbzip2 tool).
bz2.BZ2File can now also be used to create this type of file, using
the 'a' (append) mode.
（由 Nir Aides 在 bpo-1625 中贡献。）

bz2.BZ2File now implements all of the io.BufferedIOBase API,
except for the detach() and truncate() methods.

编码器¶

The mbcs codec has been rewritten to handle correctly

replace and ignore error handlers on all Windows versions. The

mbcs codec now supports all error handlers, instead of only

replace to encode and ignore to decode.

A new Windows-only codec has been added: cp65001 (bpo-13216). It is the

Windows code page 65001 (Windows UTF-8, CP_UTF8). For example, it is used

by sys.stdout if the console output code page is set to cp65001 (e.g., using

chcp65001 command).

Multibyte CJK decoders now resynchronize faster. They only ignore the first

byte of an invalid byte sequence. For example, b'\xff\n'.decode('gb2312',

'replace') now returns a \n after the replacement character.

(bpo-12016)

Incremental CJK codec encoders are no longer reset at each call to their

encode() methods. For example:

>>> importcodecs
>>> encoder=codecs.getincrementalencoder('hz')('strict')
>>> b''.join(encoder.encode(x)forxin'\u52ff\u65bd\u65bc\u4eba\u3002 Bye.')
b'~{NpJ)l6HK!#~} Bye.'

This example gives b'~{Np~}~{J)~}~{l6~}~{HK~}~{!#~}Bye.' with older Python

versions.

(bpo-12100)

The unicode_internal codec has been deprecated.

collections¶

Addition of a new ChainMap class to allow treating a

number of mappings as a single unit. (Written by Raymond Hettinger for

bpo-11089, made public in bpo-11297.)

The abstract base classes have been moved in a new collections.abc

module, to better differentiate between the abstract and the concrete

collections classes. Aliases for ABCs are still present in the

collections module to preserve existing imports. (bpo-11085)

The Counter class now supports the unary + and -

operators, as well as the in-place operators +=, -=, |=, and

&=. (Contributed by Raymond Hettinger in bpo-13121.)

contextlib¶

ExitStack now provides a solid foundation for

programmatic manipulation of context managers and similar cleanup

functionality. Unlike the previous contextlib.nested API (which was

deprecated and removed), the new API is designed to work correctly

regardless of whether context managers acquire their resources in

their __init__ method (for example, file objects) or in their

__enter__ method (for example, synchronisation objects from the

threading module).

(bpo-13585)

crypt¶

Addition of salt and modular crypt format (hashing method) and the mksalt()

function to the crypt module.

(bpo-10924)

curses¶

If the curses module is linked to the ncursesw library, use Unicode
functions when Unicode strings or characters are passed (e.g.
waddwstr()), and bytes functions otherwise (e.g. waddstr()).
Use the locale encoding instead of utf-8 to encode Unicode strings.
curses.window has a new curses.window.encoding attribute.
The curses.window class has a new get_wch()
method to get a wide character
The curses module has a new unget_wch() function to
push a wide character so the next get_wch() will return
it

（由 Iñigo Serna 在 bpo-6755 中贡献。）

datetime¶

Equality comparisons between naive and aware datetime
instances now return False instead of raising TypeError
(bpo-15006).
New datetime.datetime.timestamp() method: Return POSIX timestamp
corresponding to the datetime instance.
The datetime.datetime.strftime() method supports formatting years
older than 1000.
The datetime.datetime.astimezone() method can now be
called without arguments to convert datetime instance to the system
timezone.

decimal¶

bpo-7652 - integrate fast native decimal arithmetic.

C-module and libmpdec written by Stefan Krah.

The new C version of the decimal module integrates the high speed libmpdec

library for arbitrary precision correctly-rounded decimal floating point

arithmetic. libmpdec conforms to IBM's General Decimal Arithmetic Specification.

Performance gains range from 10x for database applications to 100x for

numerically intensive applications. These numbers are expected gains

for standard precisions used in decimal floating point arithmetic. Since

the precision is user configurable, the exact figures may vary. For example,

in integer bignum arithmetic the differences can be significantly higher.

The following table is meant as an illustration. Benchmarks are available

at http://www.bytereef.org/mpdecimal/quickstart.html.

decimal.py
_decimal
加速
pi
42.02秒
0.345秒
120倍
telco
172.19秒
5.68秒
30倍
psycopg
3.57秒
0.29秒
12倍

	decimal.py	_decimal	加速
pi	42.02秒	0.345秒	120倍
telco	172.19秒	5.68秒	30倍
psycopg	3.57秒	0.29秒	12倍

API changes¶

C模块上下文限制（如下表），具体取决于计算机体系结构：
32位
64位
MAX_PREC
425000000
999999999999999999
MAX_EMAX
425000000
999999999999999999
MIN_EMIN
-425000000
-999999999999999999

In the context templates (DefaultContext,
BasicContext and ExtendedContext)
the magnitude of Emax and
Emin has changed to 999999.

The Decimal constructor in decimal.py does not observe
the context limits and converts values with arbitrary exponents or precision
exactly. Since the C version has internal limits, the following scheme is
used: If possible, values are converted exactly, otherwise
InvalidOperation is raised and the result is NaN. In the
latter case it is always possible to use create_decimal()
in order to obtain a rounded or inexact value.

The power function in decimal.py is always correctly-rounded. In the
C version, it is defined in terms of the correctly-rounded
exp() and ln() functions,
but the final result is only "almost always correctly rounded".

In the C version, the context dictionary containing the signals is a
MutableMapping. For speed reasons,
flags and traps always
refer to the same MutableMapping that the context
was initialized with. If a new signal dictionary is assigned,
flags and traps
are updated with the new values, but they do not reference the RHS
dictionary.

Pickling a Context produces a different output in order
to have a common interchange format for the Python and C versions.

The order of arguments in the Context constructor has been
changed to match the order displayed by repr().

The watchexp parameter in the quantize() method
is deprecated.

	32位	64位
`MAX_PREC`	`425000000`	`999999999999999999`
`MAX_EMAX`	`425000000`	`999999999999999999`
`MIN_EMIN`	`-425000000`	`-999999999999999999`

email¶

Policy Framework¶

The email package now has a policy framework. A

Policy is an object with several methods and properties

that control how the email package behaves. The primary policy for Python 3.3

is the Compat32 policy, which provides backward

compatibility with the email package in Python 3.2. A policy can be

specified when an email message is parsed by a parser, or when a

Message object is created, or when an email is

serialized using a generator. Unless overridden, a policy passed

to a parser is inherited by all the Message object and sub-objects

created by the parser. By default a generator will use the policy of

the Message object it is serializing. The default policy is

compat32.

The minimum set of controls implemented by all policy objects are:

max_line_length
The maximum length, excluding the linesep character(s),
individual lines may have when a Message is
serialized. Defaults to 78.
linesep
The character used to separate individual lines when a
Message is serialized. Defaults to \n.
cte_type
7bit or 8bit. 8bit applies only to a
Bytesgenerator, and means that non-ASCII may
be used where allowed by the protocol (or where it
exists in the original input).
raise_on_defect
Causes a parser to raise error when defects are
encountered instead of adding them to the Message
object's defects list.

A new policy instance, with new settings, is created using the

clone() method of policy objects. clone takes

any of the above controls as keyword arguments. Any control not specified in

the call retains its default value. Thus you can create a policy that uses

\r\n linesep characters like this:

mypolicy=compat32.clone(linesep='\r\n')

Policies can be used to make the generation of messages in the format needed by

your application simpler. Instead of having to remember to specify

linesep='\r\n' in all the places you call a generator, you can specify

it once, when you set the policy used by the parser or the Message,

whichever your program uses to create Message objects. On the other hand,

if you need to generate messages in multiple forms, you can still specify the

parameters in the appropriate generator call. Or you can have custom

policy instances for your different cases, and pass those in when you create

the generator.

Provisional Policy with New Header API¶

While the policy framework is worthwhile all by itself, the main motivation for

introducing it is to allow the creation of new policies that implement new

features for the email package in a way that maintains backward compatibility

for those who do not use the new policies. Because the new policies introduce a

new API, we are releasing them in Python 3.3 as a provisional policy. Backwards incompatible changes (up to and including

removal of the code) may occur if deemed necessary by the core developers.

The new policies are instances of EmailPolicy,

and add the following additional controls:

refold_source
Controls whether or not headers parsed by a
parser are refolded by the
generator. It can be none, long,
or all. The default is long, which means that
source headers with a line longer than
max_line_length get refolded. none means no
line get refolded, and all means that all lines
get refolded.
header_factory
A callable that take a name and value and
produces a custom header object.

The header_factory is the key to the new features provided by the new

policies. When one of the new policies is used, any header retrieved from

a Message object is an object produced by the header_factory, and any

time you set a header on a Message it becomes an object produced by

header_factory. All such header objects have a name attribute equal

to the header name. Address and Date headers have additional attributes

that give you access to the parsed data of the header. This means you can now

do things like this:

>>> m=Message(policy=SMTP)
>>> m['To']='Éric <foo@example.com>'
>>> m['to']
'Éric <foo@example.com>'
>>> m['to'].addresses
(Address(display_name='Éric', username='foo', domain='example.com'),)
>>> m['to'].addresses[0].username
'foo'
>>> m['to'].addresses[0].display_name
'Éric'
>>> m['Date']=email.utils.localtime()
>>> m['Date'].datetime
datetime.datetime(2012, 5, 25, 21, 39, 24, 465484, tzinfo=datetime.timezone(datetime.timedelta(-1, 72000), 'EDT'))
>>> m['Date']
'Fri, 25 May 2012 21:44:27 -0400'
>>> print(m)
To: =?utf-8?q?=C3=89ric?= <foo@example.com>
Date: Fri, 25 May 2012 21:44:27 -0400

You will note that the unicode display name is automatically encoded as

utf-8 when the message is serialized, but that when the header is accessed

directly, you get the unicode version. This eliminates any need to deal with

the email.headerdecode_header() or

make_header() functions.

You can also create addresses from parts:

>>> m['cc']=[Group('pals',[Address('Bob','bob','example.com'),
... Address('Sally','sally','example.com')]),
... Address('Bonzo',addr_spec='bonz@laugh.com')]
>>> print(m)
To: =?utf-8?q?=C3=89ric?= <foo@example.com>
Date: Fri, 25 May 2012 21:44:27 -0400
cc: pals: Bob <bob@example.com>, Sally <sally@example.com>;, Bonzo <bonz@laugh.com>

Decoding to unicode is done automatically:

>>> m2=message_from_string(str(m))
>>> m2['to']
'Éric <foo@example.com>'

When you parse a message, you can use the addresses and groups

attributes of the header objects to access the groups and individual

addresses:

>>> m2['cc'].addresses
(Address(display_name='Bob', username='bob', domain='example.com'), Address(display_name='Sally', username='sally', domain='example.com'), Address(display_name='Bonzo', username='bonz', domain='laugh.com'))
>>> m2['cc'].groups
(Group(display_name='pals', addresses=(Address(display_name='Bob', username='bob', domain='example.com'), Address(display_name='Sally', username='sally', domain='example.com')), Group(display_name=None, addresses=(Address(display_name='Bonzo', username='bonz', domain='laugh.com'),))

In summary, if you use one of the new policies, header manipulation works the

way it ought to: your application works with unicode strings, and the email

package transparently encodes and decodes the unicode to and from the RFC

standard Content Transfer Encodings.

Other API Changes¶

New BytesHeaderParser, added to the parser

module to complement HeaderParser and complete the Bytes

API.

New utility functions:

format_datetime(): given a datetime,
produce a string formatted for use in an email header.
parsedate_to_datetime(): given a date string from
an email header, convert it into an aware datetime,
or a naive datetime if the offset is -0000.
localtime(): With no argument, returns the
current local time as an aware datetime using the local
timezone. Given an aware datetime,
converts it into an aware datetime using the
local timezone.

ftplib¶

ftplib.FTP now accepts a source_address keyword argument to
specify the (host,port) to use as the source address in the bind call
when creating the outgoing socket. (Contributed by Giampaolo Rodolà
in bpo-8594.)

The FTP_TLS class now provides a new
ccc() function to revert control channel back to
plaintext. This can be useful to take advantage of firewalls that know how
to handle NAT with non-secure FTP without opening fixed ports. (Contributed
by Giampaolo Rodolà in bpo-12139.)

Added ftplib.FTP.mlsd() method which provides a parsable directory
listing format and deprecates ftplib.FTP.nlst() and
ftplib.FTP.dir(). (Contributed by Giampaolo Rodolà in bpo-11072.)

functools¶

The functools.lru_cache() decorator now accepts a typed keyword

argument (that defaults to False to ensure that it caches values of

different types that compare equal in separate cache slots. (Contributed

by Raymond Hettinger in bpo-13227.)

gc¶

It is now possible to register callbacks invoked by the garbage collector

before and after collection using the new callbacks list.

hmac¶

A new compare_digest() function has been added to prevent side

channel attacks on digests through timing analysis. (Contributed by Nick

Coghlan and Christian Heimes in bpo-15061.)

http¶

http.server.BaseHTTPRequestHandler now buffers the headers and writes

them all at once when end_headers() is

called. A new method flush_headers()

can be used to directly manage when the accumulated headers are sent.

(Contributed by Andrew Schaaf in bpo-3709.)

http.server now produces valid HTML4.01strict output.

(Contributed by Ezio Melotti in bpo-13295.)

http.client.HTTPResponse now has a

readinto() method, which means it can be used

as an io.RawIOBase class. (Contributed by John Kuhn in

bpo-13464.)

html¶

html.parser.HTMLParser is now able to parse broken markup without

raising errors, therefore the strict argument of the constructor and the

HTMLParseError exception are now deprecated.

The ability to parse broken markup is the result of a number of bug fixes that

are also available on the latest bug fix releases of Python 2.7/3.2.

(Contributed by Ezio Melotti in bpo-15114, and bpo-14538,

bpo-13993, bpo-13960, bpo-13358, bpo-1745761,

bpo-755670, bpo-13357, bpo-12629, bpo-1200313,

bpo-670664, bpo-13273, bpo-12888, bpo-7311.)

A new html5 dictionary that maps HTML5 named character

references to the equivalent Unicode character(s) (e.g. html5['gt;']==

'>') has been added to the html.entities module. The dictionary is

now also used by HTMLParser. (Contributed by Ezio

Melotti in bpo-11113 and bpo-15156.)

imaplib¶

The IMAP4_SSL constructor now accepts an SSLContext

parameter to control parameters of the secure channel.

（由 Sijin Joseph 在 bpo-8808 中贡献。）

inspect¶

A new getclosurevars() function has been added. This function

reports the current binding of all names referenced from the function body and

where those names were resolved, making it easier to verify correct internal

state when testing code that relies on stateful closures.

由 Meador Inge 和 Nick Coghlan 在 bpo-13062 中贡献。

A new getgeneratorlocals() function has been added. This

function reports the current binding of local variables in the generator's

stack frame, making it easier to verify correct internal state when testing

generators.

（由 Meador Inge 在 bpo-15153 中贡献。）

io¶

The open() function has a new 'x' mode that can be used to

exclusively create a new file, and raise a FileExistsError if the file

already exists. It is based on the C11 'x' mode to fopen().

（由 David Townshend 在 bpo-12760 中贡献。）

The constructor of the TextIOWrapper class has a new

write_through optional argument. If write_through is True, calls to

write() are guaranteed not to be buffered: any data

written on the TextIOWrapper object is immediately handled to its

underlying binary buffer.

itertools¶

accumulate() now takes an optional func argument for

providing a user-supplied binary function.

logging¶

The basicConfig() function now supports an optional handlers

argument taking an iterable of handlers to be added to the root logger.

A class level attribute append_nul has

been added to SysLogHandler to allow control of the

appending of the NUL (\000) byte to syslog records, since for some

daemons it is required while for others it is passed through to the log.

math¶

The math module has a new function, log2(), which returns

the base-2 logarithm of x.

(Written by Mark Dickinson in bpo-11888.)

mmap¶

The read() method is now more compatible with other file-like

objects: if the argument is omitted or specified as None, it returns the

bytes from the current file position to the end of the mapping. (Contributed

by Petri Lehtinen in bpo-12021.)

multiprocessing¶

The new multiprocessing.connection.wait() function allows polling

multiple objects (such as connections, sockets and pipes) with a timeout.

(Contributed by Richard Oudkerk in bpo-12328.)

multiprocessing.Connection objects can now be transferred over

multiprocessing connections.

(Contributed by Richard Oudkerk in bpo-4892.)

multiprocessing.Process now accepts a daemon keyword argument

to override the default behavior of inheriting the daemon flag from

the parent process (bpo-6064).

New attribute multiprocessing.Process.sentinel allows a

program to wait on multiple Process objects at one

time using the appropriate OS primitives (for example, select on

posix systems).

New methods multiprocessing.pool.Pool.starmap() and

starmap_async() provide

itertools.starmap() equivalents to the existing

multiprocessing.pool.Pool.map() and

map_async() functions. (Contributed by Hynek

Schlawack in bpo-12708.)

nntplib¶

The nntplib.NNTP class now supports the context management protocol to

unconditionally consume socket.error exceptions and to close the NNTP

connection when done:

>>> fromnntplibimportNNTP
>>> withNNTP('news.gmane.org')asn:
... n.group('gmane.comp.python.committers')
...
('211 1755 1 1755 gmane.comp.python.committers', 1755, 1, 1755, 'gmane.comp.python.committers')
>>>

（由 Giampaolo Rodolà 在 bpo-9795 中贡献。）

os¶

The os module has a new pipe2() function that makes it
possible to create a pipe with O_CLOEXEC or
O_NONBLOCK flags set atomically. This is especially useful to
avoid race conditions in multi-threaded programs.

The os module has a new sendfile() function which provides
an efficient "zero-copy" way for copying data from one file (or socket)
descriptor to another. The phrase "zero-copy" refers to the fact that all of
the copying of data between the two descriptors is done entirely by the
kernel, with no copying of data into userspace buffers. sendfile()
can be used to efficiently copy data from a file on disk to a network socket,
e.g. for downloading a file.
(Patch submitted by Ross Lagerwall and Giampaolo Rodolà in bpo-10882.)

To avoid race conditions like symlink attacks and issues with temporary
files and directories, it is more reliable (and also faster) to manipulate
file descriptors instead of file names. Python 3.3 enhances existing functions
and introduces new functions to work on file descriptors (bpo-4761,
bpo-10755 and bpo-14626).
- The os module has a new fwalk() function similar to
  walk() except that it also yields file descriptors referring to the
  directories visited. This is especially useful to avoid symlink races.
- The following functions get new optional dir_fd (paths relative to
  directory descriptors) and/or follow_symlinks (not
  following symlinks):
  access(), chflags(), chmod(), chown(),
  link(), lstat(), mkdir(), mkfifo(),
  mknod(), open(), readlink(), remove(),
  rename(), replace(), rmdir(), stat(),
  symlink(), unlink(), utime(). Platform
  support for using these parameters can be checked via the sets
  os.supports_dir_fd and os.supports_follows_symlinks.
- The following functions now support a file descriptor for their path argument:
  chdir(), chmod(), chown(),
  execve(), listdir(), pathconf(), exists(),
  stat(), statvfs(), utime(). Platform support
  for this can be checked via the os.supports_fd set.

access() accepts an effective_ids keyword argument to turn on
using the effective uid/gid rather than the real uid/gid in the access check.
Platform support for this can be checked via the
supports_effective_ids set.

The os module has two new functions: getpriority() and
setpriority(). They can be used to get or set process
niceness/priority in a fashion similar to os.nice() but extended to all
processes instead of just the current one.
(Patch submitted by Giampaolo Rodolà in bpo-10784.)

The new os.replace() function allows cross-platform renaming of a
file with overwriting the destination. With os.rename(), an existing
destination file is overwritten under POSIX, but raises an error under
Windows.
(Contributed by Antoine Pitrou in bpo-8828.)

The stat family of functions (stat(), fstat(),
and lstat()) now support reading a file's timestamps
with nanosecond precision. Symmetrically, utime()
can now write file timestamps with nanosecond precision. (Contributed by
Larry Hastings in bpo-14127.)

The new os.get_terminal_size() function queries the size of the
terminal attached to a file descriptor. See also
shutil.get_terminal_size().
(Contributed by Zbigniew Jędrzejewski-Szmek in bpo-13609.)

New functions to support Linux extended attributes (bpo-12720):
getxattr(), listxattr(), removexattr(),
setxattr().

New interface to the scheduler. These functions
control how a process is allocated CPU time by the operating system. New
functions:
sched_get_priority_max(), sched_get_priority_min(),
sched_getaffinity(), sched_getparam(),
sched_getscheduler(), sched_rr_get_interval(),
sched_setaffinity(), sched_setparam(),
sched_setscheduler(), sched_yield(),

New functions to control the file system:
- posix_fadvise(): Announces an intention to access data in a
  specific pattern thus allowing the kernel to make optimizations.
- posix_fallocate(): Ensures that enough disk space is allocated
  for a file.
- sync(): Force write of everything to disk.

Additional new posix functions:
- lockf(): Apply, test or remove a POSIX lock on an open file descriptor.
- pread(): Read from a file descriptor at an offset, the file
  offset remains unchanged.
- pwrite(): Write to a file descriptor from an offset, leaving
  the file offset unchanged.
- readv(): Read from a file descriptor into a number of writable buffers.
- truncate(): Truncate the file corresponding to path, so that
  it is at most length bytes in size.
- waitid(): Wait for the completion of one or more child processes.
- writev(): Write the contents of buffers to a file descriptor,
  where buffers is an arbitrary sequence of buffers.
- getgrouplist() (bpo-9344): Return list of group ids that
  specified user belongs to.

times() and uname(): Return type changed from a tuple to
a tuple-like object with named attributes.

Some platforms now support additional constants for the lseek()
function, such as os.SEEK_HOLE and os.SEEK_DATA.

New constants RTLD_LAZY, RTLD_NOW,
RTLD_GLOBAL, RTLD_LOCAL, RTLD_NODELETE,
RTLD_NOLOAD, and RTLD_DEEPBIND are available on
platforms that support them. These are for use with the
sys.setdlopenflags() function, and supersede the similar constants
defined in ctypes and DLFCN. (Contributed by Victor Stinner
in bpo-13226.)

os.symlink() now accepts (and ignores) the target_is_directory
keyword argument on non-Windows platforms, to ease cross-platform support.

pdb¶

Tab-completion is now available not only for command names, but also their

arguments. For example, for the break command, function and file names

are completed.

（由 Georg Brandl 在 bpo-14210 中贡献）

pickle¶

pickle.Pickler objects now have an optional

dispatch_table attribute allowing per-pickler

reduction functions to be set.

（由 Richard Oudkerk 在 bpo-14166 中贡献。）

pydoc¶

The Tk GUI and the serve() function have been removed from the

pydoc module: pydoc-g and serve() have been deprecated

in Python 3.2.

re¶

str regular expressions now support \u and \U escapes.

（由 Serhiy Storchaka 在 bpo-3665 中贡献。）

sched¶

run() now accepts a blocking parameter which when
set to false makes the method execute the scheduled events due to expire
soonest (if any) and then return immediately.
This is useful in case you want to use the scheduler in
non-blocking applications. (Contributed by Giampaolo Rodolà in bpo-13449.)

scheduler class can now be safely used in multi-threaded
environments. (Contributed by Josiah Carlson and Giampaolo Rodolà in
bpo-8684.)

timefunc and delayfunct parameters of scheduler class
constructor are now optional and defaults to time.time() and
time.sleep() respectively. (Contributed by Chris Clark in
bpo-13245.)

enter() and enterabs()
argument parameter is now optional. (Contributed by Chris Clark in
bpo-13245.)

enter() and enterabs()
now accept a kwargs parameter. (Contributed by Chris Clark in
bpo-13245.)

select¶

Solaris and derivative platforms have a new class select.devpoll

for high performance asynchronous sockets via /dev/poll.

(Contributed by Jesús Cea Avión in bpo-6397.)

shlex¶

The previously undocumented helper function quote from the

pipes modules has been moved to the shlex module and

documented. quote() properly escapes all characters in a string

that might be otherwise given special meaning by the shell.

shutil¶

新的函数：
- disk_usage(): provides total, used and free disk space
  statistics. (Contributed by Giampaolo Rodolà in bpo-12442.)
- chown(): allows one to change user and/or group of the given
  path also specifying the user/group names and not only their numeric
  ids. (Contributed by Sandro Tosi in bpo-12191.)
- shutil.get_terminal_size(): returns the size of the terminal window
  to which the interpreter is attached. (Contributed by Zbigniew
  Jędrzejewski-Szmek in bpo-13609.)

copy2() and copystat() now preserve file
timestamps with nanosecond precision on platforms that support it.
They also preserve file "extended attributes" on Linux. (Contributed
by Larry Hastings in bpo-14127 and bpo-15238.)

Several functions now take an optional symlinks argument: when that
parameter is true, symlinks aren't dereferenced and the operation instead
acts on the symlink itself (or creates one, if relevant).
(Contributed by Hynek Schlawack in bpo-12715.)

When copying files to a different file system, move() now
handles symlinks the way the posix mv command does, recreating the
symlink rather than copying the target file contents. (Contributed by
Jonathan Niehof in bpo-9993.) move() now also returns
the dst argument as its result.

rmtree() is now resistant to symlink attacks on platforms
which support the new dir_fd parameter in os.open() and
os.unlink(). (Contributed by Martin von Löwis and Hynek Schlawack
in bpo-4489.)

signal¶

The signal module has new functions:
- pthread_sigmask(): fetch and/or change the signal mask of the
  calling thread (Contributed by Jean-Paul Calderone in bpo-8407);
- pthread_kill(): send a signal to a thread;
- sigpending(): examine pending functions;
- sigwait(): wait a signal;
- sigwaitinfo(): wait for a signal, returning detailed
  information about it;
- sigtimedwait(): like sigwaitinfo() but with a
  timeout.

The signal handler writes the signal number as a single byte instead of
a nul byte into the wakeup file descriptor. So it is possible to wait more
than one signal and know which signals were raised.

signal.signal() and signal.siginterrupt() raise an OSError,
instead of a RuntimeError: OSError has an errno attribute.

smtpd¶

The smtpd module now supports RFC 5321 (extended SMTP) and RFC 1870

(size extension). Per the standard, these extensions are enabled if and only

if the client initiates the session with an EHLO command.

(Initial ELHO support by Alberto Trevino. Size extension by Juhana

Jauhiainen. Substantial additional work on the patch contributed by Michele

Orrù and Dan Boswell. bpo-8739)

smtplib¶

The SMTP, SMTP_SSL, and

LMTP classes now accept a source_address keyword argument

to specify the (host,port) to use as the source address in the bind call

when creating the outgoing socket. (Contributed by Paulo Scardine in

bpo-11281.)

SMTP now supports the context management protocol, allowing an

SMTP instance to be used in a with statement. (Contributed

by Giampaolo Rodolà in bpo-11289.)

The SMTP_SSL constructor and the starttls()

method now accept an SSLContext parameter to control parameters of the secure

channel. (Contributed by Kasun Herath in bpo-8809.)

socket¶

The socket class now exposes additional methods to process
ancillary data when supported by the underlying platform:
- sendmsg()
- recvmsg()
- recvmsg_into()
(Contributed by David Watson in bpo-6560, based on an earlier patch by
Heiko Wundram)

The socket class now supports the PF_CAN protocol family
(https://en.wikipedia.org/wiki/Socketcan), on Linux
(https://lwn.net/Articles/253425).
(Contributed by Matthias Fuchs, updated by Tiago Gonçalves in bpo-10141.)

The socket class now supports the PF_RDS protocol family
(https://en.wikipedia.org/wiki/Reliable_Datagram_Sockets and
https://oss.oracle.com/projects/rds/).

The socket class now supports the PF_SYSTEM protocol
family on OS X. (Contributed by Michael Goderbauer in bpo-13777.)

New function sethostname() allows the hostname to be set
on unix systems if the calling process has sufficient privileges.
(Contributed by Ross Lagerwall in bpo-10866.)

socketserver¶

BaseServer now has an overridable method

service_actions() that is called by the

serve_forever() method in the service loop.

ForkingMixIn now uses this to clean up zombie

child processes. (Contributed by Justin Warkentin in bpo-11109.)

sqlite3¶

New sqlite3.Connection method

set_trace_callback() can be used to capture a trace of

all sql commands processed by sqlite. (Contributed by Torsten Landschoff

in bpo-11688.)

ssl¶

The ssl module has two new random generation functions:
- RAND_bytes(): generate cryptographically span
  pseudo-random bytes.
- RAND_pseudo_bytes(): generate pseudo-random bytes.
（由 Victor Stinner 在 bpo-12049 中贡献。）

The ssl module now exposes a finer-grained exception hierarchy
in order to make it easier to inspect the various kinds of errors.
(Contributed by Antoine Pitrou in bpo-11183.)

load_cert_chain() now accepts a password argument
to be used if the private key is encrypted.
(Contributed by Adam Simpkins in bpo-12803.)

Diffie-Hellman key exchange, both regular and Elliptic Curve-based, is
now supported through the load_dh_params() and
set_ecdh_curve() methods.
(Contributed by Antoine Pitrou in bpo-13626 and bpo-13627.)

SSL sockets have a new get_channel_binding() method
allowing the implementation of certain authentication mechanisms such as
SCRAM-SHA-1-PLUS. (Contributed by Jacek Konieczny in bpo-12551.)

You can query the SSL compression algorithm used by an SSL socket, thanks
to its new compression() method. The new attribute
OP_NO_COMPRESSION can be used to disable compression.
(Contributed by Antoine Pitrou in bpo-13634.)

Support has been added for the Next Protocol Negotiation extension using
the ssl.SSLContext.set_npn_protocols() method.
(Contributed by Colin Marc in bpo-14204.)

SSL errors can now be introspected more easily thanks to
library and reason attributes.
(Contributed by Antoine Pitrou in bpo-14837.)

The get_server_certificate() function now supports IPv6.
(Contributed by Charles-François Natali in bpo-11811.)

New attribute OP_CIPHER_SERVER_PREFERENCE allows setting
SSLv3 server sockets to use the server's cipher ordering preference rather
than the client's (bpo-13635).

stat¶

The undocumented tarfile.filemode function has been moved to

stat.filemode(). It can be used to convert a file's mode to a string of

the form '-rwxrwxrwx'.

（由 Giampaolo Rodolà 在 bpo-14807 中贡献。）

struct¶

The struct module now supports ssize_t and size_t via the

new codes n and N, respectively. (Contributed by Antoine Pitrou

in bpo-3163.)

subprocess¶

Command strings can now be bytes objects on posix platforms. (Contributed by

Victor Stinner in bpo-8513.)

A new constant DEVNULL allows suppressing output in a

platform-independent fashion. (Contributed by Ross Lagerwall in

bpo-5870.)

sys¶

The sys module has a new thread_infonamed

tuple holding information about the thread implementation

(bpo-11223).

tarfile¶

tarfile now supports lzma encoding via the lzma module.

(Contributed by Lars Gustäbel in bpo-5689.)

tempfile¶

tempfile.SpooledTemporaryFile's

truncate() method now accepts

a size parameter. (Contributed by Ryan Kelly in bpo-9957.)

textwrap¶

The textwrap module has a new indent() that makes

it straightforward to add a common prefix to selected lines in a block

of text (bpo-13857).

threading¶

threading.Condition, threading.Semaphore,

threading.BoundedSemaphore, threading.Event, and

threading.Timer, all of which used to be factory functions returning a

class instance, are now classes and may be subclassed. (Contributed by Éric

Araujo in bpo-10968.)

The threading.Thread constructor now accepts a daemon keyword

argument to override the default behavior of inheriting the daemon flag

value from the parent thread (bpo-6064).

The formerly private function _thread.get_ident is now available as the

public function threading.get_ident(). This eliminates several cases of

direct access to the _thread module in the stdlib. Third party code that

used _thread.get_ident should likewise be changed to use the new public

interface.

time¶

The PEP 418 added new functions to the time module:

get_clock_info(): Get information on a clock.

monotonic(): Monotonic clock (cannot go backward), not affected
by system clock updates.

perf_counter(): Performance counter with the highest available
resolution to measure a short duration.

process_time(): Sum of the system and user CPU time of the
current process.

Other new functions:

clock_getres(), clock_gettime() and
clock_settime() functions with CLOCK_xxx constants.
(Contributed by Victor Stinner in bpo-10278.)

To improve cross platform consistency, sleep() now raises a

ValueError when passed a negative sleep value. Previously this was an

error on posix, but produced an infinite sleep on Windows.

types¶

Add a new types.MappingProxyType class: Read-only proxy of a mapping.

(bpo-14386)

The new functions types.new_class() and types.prepare_class() provide support

for PEP 3115 compliant dynamic type creation. (bpo-14588)

unittest¶

assertRaises(), assertRaisesRegex(), assertWarns(), and

assertWarnsRegex() now accept a keyword argument msg when used as

context managers. (Contributed by Ezio Melotti and Winston Ewert in

bpo-10775.)

unittest.TestCase.run() now returns the TestResult

object.

urllib¶

The Request class, now accepts a method argument

used by get_method() to determine what HTTP method

should be used. For example, this will send a 'HEAD' request:

>>> urlopen(Request('https://www.python.org',method='HEAD'))

(bpo-1673007)

webbrowser¶

The webbrowser module supports more "browsers": Google Chrome (named

chrome, chromium, chrome-browser or

chromium-browser depending on the version and operating system),

and the generic launchers xdg-open, from the FreeDesktop.org

project, and gvfs-open, which is the default URI handler for GNOME

3. (The former contributed by Arnaud Calmettes in bpo-13620, the latter

by Matthias Klose in bpo-14493.)

xml.etree.ElementTree¶

The xml.etree.ElementTree module now imports its C accelerator by

default; there is no longer a need to explicitly import

xml.etree.cElementTree (this module stays for backwards compatibility,

but is now deprecated). In addition, the iter family of methods of

Element has been optimized (rewritten in C).

The module's documentation has also been greatly improved with added examples

and a more detailed reference.

zlib¶

New attribute zlib.Decompress.eof makes it possible to distinguish

between a properly-formed compressed stream and an incomplete or truncated one.

(Contributed by Nadeem Vawda in bpo-12646.)

New attribute zlib.ZLIB_RUNTIME_VERSION reports the version string of

the underlying zlib library that is loaded at runtime. (Contributed by

Torsten Landschoff in bpo-12306.)

性能优化¶

Major performance enhancements have been added:

Thanks to PEP 393, some operations on Unicode strings have been optimized:
- the memory footprint is divided by 2 to 4 depending on the text
- encode an ASCII string to UTF-8 doesn't need to encode characters anymore,
  the UTF-8 representation is shared with the ASCII representation
- the UTF-8 encoder has been optimized
- repeating a single ASCII letter and getting a substring of an ASCII string
  is 4 times faster

UTF-8 is now 2x to 4x faster. UTF-16 encoding is now up to 10x faster.
(Contributed by Serhiy Storchaka, bpo-14624, bpo-14738 and
bpo-15026.)

构建和 C API 的改变¶

Changes to Python's build process and to the C API include:

新的 PEP 3118 相关功能：
- PyMemoryView_FromMemory()

PEP 393 添加了新的 Unicode 类型，宏和函数
- 高阶 API
  - PyUnicode_CopyCharacters()
  - PyUnicode_FindChar()
  - PyUnicode_GetLength(), PyUnicode_GET_LENGTH
  - PyUnicode_New()
  - PyUnicode_Substring()
  - PyUnicode_ReadChar(), PyUnicode_WriteChar()
- 低阶 API:
  - Py_UCS1, Py_UCS2, Py_UCS4 types
  - PyASCIIObject 和 PyCompactUnicodeObject 结构
  - PyUnicode_READY
  - PyUnicode_FromKindAndData()
  - PyUnicode_AsUCS4(), PyUnicode_AsUCS4Copy()
  - PyUnicode_DATA, PyUnicode_1BYTE_DATA,
    PyUnicode_2BYTE_DATA, PyUnicode_4BYTE_DATA
  - PyUnicode_KIND 使用 PyUnicode_Kind 枚举: PyUnicode_WCHAR_KIND, PyUnicode_1BYTE_KIND, PyUnicode_2BYTE_KIND, PyUnicode_4BYTE_KIND
  - PyUnicode_READ, PyUnicode_READ_CHAR, PyUnicode_WRITE
  - PyUnicode_MAX_CHAR_VALUE

PyArg_ParseTuple 现在接受 c 格式的 bytearray (bpo-12380)。

弃用¶

不支持的操作系统¶

由于缺少维护人员，不再支持 OS/2 和 VMS 系统。

由于维护负担，将 COMSPEC 设置为 command.com 的 Windows平台（含Windows 2000）不再受支持。

OSF支持在3.2中被弃用，现在已经被完全删除。

已弃用的 Python 模块、函数和方法¶

Passing a non-empty string to object.__format__() is deprecated, and
will produce a TypeError in Python 3.4 (bpo-9856).

The unicode_internal codec has been deprecated because of the
PEP 393, use UTF-8, UTF-16 (utf-16-le or utf-16-be), or UTF-32
(utf-32-le or utf-32-be)

ftplib.FTP.nlst() and ftplib.FTP.dir(): use
ftplib.FTP.mlsd()

platform.popen(): use the subprocess module. Check especially
the 使用 subprocess 模块替换旧函数 section (bpo-11377).

bpo-13374: The Windows bytes API has been deprecated in the os
module. Use Unicode filenames, instead of bytes filenames, to not depend on
the ANSI code page anymore and to support any filename.

bpo-13988: The xml.etree.cElementTree module is deprecated. The
accelerator is used automatically whenever available.

The behaviour of time.clock() depends on the platform: use the new
time.perf_counter() or time.process_time() function instead,
depending on your requirements, to have a well defined behaviour.

The os.stat_float_times() function is deprecated.

abc module:
- abc.abstractproperty has been deprecated, use property
  with abc.abstractmethod() instead.
- abc.abstractclassmethod has been deprecated, use
  classmethod with abc.abstractmethod() instead.
- abc.abstractstaticmethod has been deprecated, use
  staticmethod with abc.abstractmethod() instead.

importlib package:
- importlib.abc.SourceLoader.path_mtime() is now deprecated in favour of
  importlib.abc.SourceLoader.path_stats() as bytecode files now store
  both the modification time and size of the source file the bytecode file was
  compiled from.

已弃用的 C API 函数和类型¶

Py_UNICODE 已经在 PEP 393 弃用，并将于 Python 4 中移除。所有使用此类型的函数都已弃用：

Unicode functions and methods using Py_UNICODE and

Py_UNICODE* types:

PyUnicode_FromUnicode: 使用 PyUnicode_FromWideChar() 或 PyUnicode_FromKindAndData()

PyUnicode_AS_UNICODE, PyUnicode_AsUnicode(), PyUnicode_AsUnicodeAndSize(): 使用 PyUnicode_AsWideCharString()

PyUnicode_AS_DATA: 使用 PyUnicode_DATA 以及 PyUnicode_READ 和 PyUnicode_WRITE

PyUnicode_GET_SIZE, PyUnicode_GetSize(): 使用 PyUnicode_GET_LENGTH 或 PyUnicode_GetLength()

PyUnicode_GET_DATA_SIZE: 使用 PyUnicode_GET_LENGTH(str)*PyUnicode_KIND(str) (仅适用于现成的字符串)

PyUnicode_AsUnicodeCopy(): 使用 PyUnicode_AsUCS4Copy() 或 PyUnicode_AsWideCharString()

PyUnicode_GetMax()

Functions and macros manipulating Py_UNICODE* strings:

Py_UNICODE_strlen: 使用 PyUnicode_GetLength() 或 PyUnicode_GET_LENGTH

Py_UNICODE_strcat: 使用 PyUnicode_CopyCharacters() 或 PyUnicode_FromFormat()

Py_UNICODE_strcpy, Py_UNICODE_strncpy, Py_UNICODE_COPY: 使用 PyUnicode_CopyCharacters() 或 PyUnicode_Substring()

Py_UNICODE_strcmp: 使用 PyUnicode_Compare()

Py_UNICODE_strncmp: 使用 PyUnicode_Tailmatch()

Py_UNICODE_strchr, Py_UNICODE_strrchr: 使用 PyUnicode_FindChar()

Py_UNICODE_FILL: 使用 PyUnicode_Fill()

Py_UNICODE_MATCH

编码器:

PyUnicode_Encode(): 使用 PyUnicode_AsEncodedObject()

PyUnicode_EncodeUTF7()

PyUnicode_EncodeUTF8(): 使用 PyUnicode_AsUTF8() 或 PyUnicode_AsUTF8String()

PyUnicode_EncodeUTF32()

PyUnicode_EncodeUTF16()

PyUnicode_EncodeUnicodeEscape:() 使用 PyUnicode_AsUnicodeEscapeString()

PyUnicode_EncodeRawUnicodeEscape:() 使用 PyUnicode_AsRawUnicodeEscapeString()

PyUnicode_EncodeLatin1(): 使用 PyUnicode_AsLatin1String()

PyUnicode_EncodeASCII(): 使用 PyUnicode_AsASCIIString()

PyUnicode_EncodeCharmap()

PyUnicode_TranslateCharmap()

PyUnicode_EncodeMBCS(): 使用 PyUnicode_AsMBCSString() 或 PyUnicode_EncodeCodePage() (和 CP_ACP code_page)

PyUnicode_EncodeDecimal(),
PyUnicode_TransformDecimalToASCII()

弃用的功能¶

The array module's 'u' format code is now deprecated and will be

removed in Python 4 together with the rest of the (Py_UNICODE) API.

移植到 Python 3.3¶

本节列出了先前描述的更改以及可能需要更改代码的其他错误修正.

Porting Python code¶

Hash randomization is enabled by default. Set the PYTHONHASHSEED
environment variable to 0 to disable hash randomization. See also the
object.__hash__() method.

bpo-12326: On Linux, sys.platform doesn't contain the major version
anymore. It is now always 'linux', instead of 'linux2' or 'linux3' depending
on the Linux version used to build Python. Replace sys.platform == 'linux2'
with sys.platform.startswith('linux'), or directly sys.platform == 'linux' if
you don't need to support older Python versions.

bpo-13847, bpo-14180: time and datetime:
OverflowError is now raised instead of ValueError if a
timestamp is out of range. OSError is now raised if C functions
gmtime() or localtime() failed.

The default finders used by import now utilize a cache of what is contained
within a specific directory. If you create a Python source file or sourceless
bytecode file, make sure to call importlib.invalidate_caches() to clear
out the cache for the finders to notice the new file.

ImportError now uses the full name of the module that was attempted to
be imported. Doctests that check ImportErrors' message will need to be
updated to use the full name of the module instead of just the tail of the
name.

The index argument to __import__() now defaults to 0 instead of -1
and no longer support negative values. It was an oversight when PEP 328 was
implemented that the default value remained -1. If you need to continue to
perform a relative import followed by an absolute import, then perform the
relative import using an index of 1, followed by another import using an
index of 0. It is preferred, though, that you use
importlib.import_module() rather than call __import__() directly.

__import__() no longer allows one to use an index value other than 0
for top-level modules. E.g. __import__('sys',level=1) is now an error.

Because sys.meta_path and sys.path_hooks now have finders on
them by default, you will most likely want to use list.insert() instead
of list.append() to add to those lists.

Because None is now inserted into sys.path_importer_cache, if you
are clearing out entries in the dictionary of paths that do not have a
finder, you will need to remove keys paired with values of None and
imp.NullImporter to be backwards-compatible. This will lead to extra
overhead on older versions of Python that re-insert None into
sys.path_importer_cache where it represents the use of implicit
finders, but semantically it should not change anything.

importlib.abc.Finder no longer specifies a find_module() abstract
method that must be implemented. If you were relying on subclasses to
implement that method, make sure to check for the method's existence first.
You will probably want to check for find_loader() first, though, in the
case of working with path entry finders.

pkgutil has been converted to use importlib internally. This
eliminates many edge cases where the old behaviour of the PEP 302 import
emulation failed to match the behaviour of the real import system. The
import emulation itself is still present, but is now deprecated. The
pkgutil.iter_importers() and pkgutil.walk_packages() functions
special case the standard import hooks so they are still supported even
though they do not provide the non-standard iter_modules() method.

A longstanding RFC-compliance bug (bpo-1079) in the parsing done by
email.header.decode_header() has been fixed. Code that uses the
standard idiom to convert encoded headers into unicode
(str(make_header(decode_header(h))) will see no change, but code that
looks at the individual tuples returned by decode_header will see that
whitespace that precedes or follows ASCII sections is now included in the
ASCII section. Code that builds headers using make_header should
also continue to work without change, since make_header continues to add
whitespace between ASCII and non-ASCII sections if it is not already
present in the input strings.

email.utils.formataddr() now does the correct content transfer
encoding when passed non-ASCII display names. Any code that depended on
the previous buggy behavior that preserved the non-ASCII unicode in the
formatted output string will need to be changed (bpo-1690608).

poplib.POP3.quit() may now raise protocol errors like all other
poplib methods. Code that assumes quit does not raise
poplib.error_proto errors may need to be changed if errors on quit
are encountered by a particular application (bpo-11291).

The strict argument to email.parser.Parser, deprecated since
Python 2.4, has finally been removed.

The deprecated method unittest.TestCase.assertSameElements has been
removed.

The deprecated variable time.accept2dyear has been removed.

The deprecated Context._clamp attribute has been removed from the
decimal module. It was previously replaced by the public attribute
clamp. (See bpo-8540.)

The undocumented internal helper class SSLFakeFile has been removed
from smtplib, since its functionality has long been provided directly
by socket.socket.makefile().

Passing a negative value to time.sleep() on Windows now raises an
error instead of sleeping forever. It has always raised an error on posix.

The ast.__version__ constant has been removed. If you need to
make decisions affected by the AST version, use sys.version_info
to make the decision.

Code that used to work around the fact that the threading module used
factory functions by subclassing the private classes will need to change to
subclass the now-public classes.

The undocumented debugging machinery in the threading module has been
removed, simplifying the code. This should have no effect on production
code, but is mentioned here in case any application debug frameworks were
interacting with it (bpo-13550).

Porting C code¶

In the course of changes to the buffer API the undocumented
smalltable member of the
Py_buffer structure has been removed and the
layout of the PyMemoryViewObject has changed.
All extensions relying on the relevant parts in memoryobject.h
or object.h must be rebuilt.

Due to PEP 393, the Py_UNICODE type and all
functions using this type are deprecated (but will stay available for
at least five years). If you were using low-level Unicode APIs to
construct and access unicode objects and you want to benefit of the
memory footprint reduction provided by PEP 393, you have to convert
your code to the new Unicode API.
However, if you only have been using high-level functions such as
PyUnicode_Concat(), PyUnicode_Join() or
PyUnicode_FromFormat(), your code will automatically take
advantage of the new unicode representations.

PyImport_GetMagicNumber() now returns -1 upon failure.

As a negative value for the level argument to __import__() is no
longer valid, the same now holds for PyImport_ImportModuleLevel().
This also means that the value of level used by
PyImport_ImportModuleEx() is now 0 instead of -1.

Building C extensions¶

The range of possible file names for C extensions has been narrowed.
Very rarely used spellings have been suppressed: under POSIX, files
named xxxmodule.so, xxxmodule.abi3.so and
xxxmodule.cpython-*.so are no longer recognized as implementing
the xxx module. If you had been generating such files, you have
to switch to the other spellings (i.e., remove the module string
from the file names).
(implemented in bpo-14040.)

Command Line Switch Changes¶

The -Q command-line flag and related artifacts have been removed. Code
checking sys.flags.division_warning will need updating.
（bpo-14807，由 Éric Araujo 贡献。）

When python is started with -S, importsite
will no longer add site-specific paths to the module search paths. In
previous versions, it did.
(bpo-11591, contributed by Carl Meyer with editions by Éric Araujo.)

以上是 Python3.3有什么新变化的全部内容，来源链接： utcz.com/z/508501.html

max_line_length	The maximum length, excluding the linesep character(s), individual lines may have when a `Message` is serialized. Defaults to 78.
linesep	The character used to separate individual lines when a `Message` is serialized. Defaults to `\n`.
cte_type	`7bit` or `8bit`. `8bit` applies only to a `Bytesgenerator`, and means that non-ASCII may be used where allowed by the protocol (or where it exists in the original input).
raise_on_defect	Causes a `parser` to raise error when defects are encountered instead of adding them to the `Message` object's `defects` list.

Python3.3有什么新变化

摘要 - 发布重点¶

PEP 405: 虚拟环境¶

PEP 420: 隐式命名空间包¶

PEP 3118: 新的内存视图实现和缓冲协议文档¶

相关特性¶

API changes¶

PEP 393: 灵活的字符串表示¶

Functionality¶

Performance and resource usage¶

PEP 397: 适用于Windows的Python启动器¶

PEP 3151: 重写 OS 和 IO 异常的层次结构¶

PEP 380: 委托给子生成器的语法¶

PEP 409: 清除异常上下文¶

PEP 414: 显式的Unicode文本¶

PEP 3155: 类和函数的限定名称¶

PEP 412: Key-Sharing Dictionary¶

PEP 362: 函数签名对象¶

PEP 421: 添加 sys.implementation¶

SimpleNamespace¶

Using importlib as the Implementation of Import¶

New APIs¶

Visible Changes¶

其他语言特性修改¶

A Finer-Grained Import Lock¶

Builtin functions and types¶

新增模块¶

faulthandler¶

ipaddress¶

lzma¶

改进的模块¶

abc¶

array¶

base64¶

binascii¶

bz2¶

编码器¶

collections¶

contextlib¶

crypt¶

curses¶

datetime¶

decimal¶

相关特性¶

API changes¶

email¶

Policy Framework¶

Provisional Policy with New Header API¶

Other API Changes¶

ftplib¶

functools¶

gc¶

hmac¶

http¶

html¶

imaplib¶

inspect¶

io¶

itertools¶

logging¶

math¶

mmap¶

multiprocessing¶

nntplib¶

os¶

pdb¶

pickle¶

pydoc¶

re¶

sched¶

select¶

shlex¶

shutil¶

signal¶

smtpd¶

smtplib¶

socket¶

socketserver¶

sqlite3¶

ssl¶