- Python 3.5 有什么新变化
- 摘要 — 发布重点
- 新的特性
- PEP 492 - 使用 async 和 await 语法实现协程
- PEP 465 - 用于矩阵乘法的专用中缀运算符
- PEP 448 - Additional Unpacking Generalizations
- PEP 461 - percent formatting support for bytes and bytearray
- PEP 484 —— 类型注解
- PEP 471 - os.scandir() function — a better and faster directory iterator
- PEP 475: Retry system calls failing with EINTR
- PEP 479: Change StopIteration handling inside generators
- PEP 485: A function for testing approximate equality
- PEP 486: Make the Python Launcher aware of virtual environments
- PEP 488: Elimination of PYO files
- PEP 489: Multi-phase extension module initialization
- 其他语言特性修改
- 新增模块
- 改进的模块
- argparse
- asyncio
- bz2
- cgi
- cmath
- code
- collections
- collections.abc
- compileall
- concurrent.futures
- configparser
- contextlib
- csv
- curses
- dbm
- difflib
- distutils
- doctest
- enum
- faulthandler
- functools
- glob
- gzip
- heapq
- http
- http.client
- idlelib 与 IDLE
- imaplib
- imghdr
- importlib
- inspect
- io
- ipaddress
- json
- linecache
- locale
- logging
- lzma
- math
- multiprocessing
- operator
- os
- pathlib
- pickle
- poplib
- re
- readline
- selectors
- shutil
- signal
- smtpd
- smtplib
- sndhdr
- socket
- ssl
- sqlite3
- subprocess
- sys
- sysconfig
- tarfile
- threading
- time
- timeit
- tkinter
- 回溯
- types
- unicodedata
- unittest
- unittest.mock
- urllib
- wsgiref
- xmlrpc
- xml.sax
- zipfile
- 其他模块级更改
- 性能优化
- 构建和 C API 的改变
- 弃用
- 移除
- 移植到Python 3.5
- Python 3.5.4 的显著变化
Python 3.5 有什么新变化
编者
Elvis Pranskevichus <elvis@magic.io>, Yury Selivanov <yury@magic.io>
这篇文章介绍了 Python 3.5 相比 3.4 增加的新特性。 Python 3.5 发布于 2015 年 9 月 13 日。 更完成的变化清单请参阅 changelog。
参见
PEP 478 - Python 3.5 发布计划
摘要 — 发布重点
新的语法特性:
新的库模块:
新的内置特性:
bytes % args
,bytearray % args
: PEP 461 — 为字节串和字节数组增加%
格式化。新增 bytes.hex(), bytearray.hex() 和 memoryview.hex() 方法。 (由 Arnon Yaari 在 bpo-9951 中贡献。)
memoryview 现在支持元组索引(包括多维度)。 (由 Antoine Pitrou 在 bpo-23632 中贡献。)
生成器具有一个新的
gi_yieldfrom
属性,它将返回yield from
表达式所迭代的对象。 (由 Benno Leslie 和 Yury Selivanov 在 bpo-24450 中贡献。)现在当达到最大递归尝试时将引发新的 RecursionError 异常。 (由 Georg Brandl 在 bpo-19235 中贡献。)
CPython 实现的改进:
当
LC_TYPE
语言区域为 POSIX 语言区域(即C
语言区域)时,sys.stdin 和 sys.stdout 现在将使用surrogateescape
错误处理句柄,而不是strict
错误处理句柄。 (由 Victor Stinner 在 bpo-19977 中贡献。).pyo
文件已不再被使用而是被替换为一个更灵活的方案即在.pyc
名称中显式地包括优化级别。 (参见 PEP 488 概览。)内置与扩展模块现在将经过多阶段的过程被初始化,这类似于 Python 模块的加载方式。 (参见 PEP 489 概览。)
标准库中的重大改进:
collections.OrderedDict 现在已 用 C 实现,这使它的速度快了 4 到 100 部。
The ssl 模块获得了 对内存 BIO 的支持,它使得 SSL 协议处理与网络 IO 实现了解耦。
新的 os.scandir() 函数提供了对于目录遍历 更好和明显更快速的方式。
functools.lru_cache() 已经大部分 用 C 重新实现,产生了更好的性能。
新的 subprocess.run() 函数提供了一个 运行子进程的简便方式。
安全改进:
SSLv3 目前在整个标准库中被禁用。 它仍然可以通过手动实例化一个 ssl.SSLContext 来启用。 (请参阅 bpo-22638 了解详情;此修改已向下移植到 CPython 3.4 和 2.7。)
HTTP cookie 解析现在将更严格,以防止潜在的注入攻击。 (由 Antoine Pitrou 在 bpo-22796 中贡献。)
Windows改进:
使用新的 Windows 安装器替代了旧版 MSI。 请参阅 在Windows上使用 Python 了解详情。
Windows 编译版现在使用 Microsoft Visual C++ 14.0,扩展模块也应当使用同一版本。
请继续阅读有关针对用户的改变的完整清单,包括许多其他较小的改进、CPython 优化、弃用以及潜在的移植问题。
新的特性
PEP 492 - 使用 async 和 await 语法实现协程
PEP 492 通过添加 可等待对象, 协程函数, 异步迭代 和 异步上下文管理器 极大地改善了 Python 对异步编程的支持。
协程函数是使用新的 async def 语法来声明的:
>>> async def coro():
... return 'spam'
在协程函数内部,新的 await 表达式可用于挂起协程的执行直到其结果可用。 任何对象都可以被 等待,只要它通过定义 __await__()
方法实现了 awaitable 协议。
PEP 492 还增加了 async for 语句用于方便地迭代异步可迭代对象。
An example of a rudimentary HTTP client written using the new syntax:
import asyncio
async def http_get(domain):
reader, writer = await asyncio.open_connection(domain, 80)
writer.write(b'\r\n'.join([
b'GET / HTTP/1.1',
b'Host: %b' % domain.encode('latin-1'),
b'Connection: close',
b'', b''
]))
async for line in reader:
print('>>>', line)
writer.close()
loop = asyncio.get_event_loop()
try:
loop.run_until_complete(http_get('example.com'))
finally:
loop.close()
Similarly to asynchronous iteration, there is a new syntax for asynchronous context managers. The following script:
import asyncio
async def coro(name, lock):
print('coro {}: waiting for lock'.format(name))
async with lock:
print('coro {}: holding the lock'.format(name))
await asyncio.sleep(1)
print('coro {}: releasing the lock'.format(name))
loop = asyncio.get_event_loop()
lock = asyncio.Lock()
coros = asyncio.gather(coro(1, lock), coro(2, lock))
try:
loop.run_until_complete(coros)
finally:
loop.close()
将输出:
coro 2: waiting for lock
coro 2: holding the lock
coro 1: waiting for lock
coro 2: releasing the lock
coro 1: holding the lock
coro 1: releasing the lock
Note that both async for and async with can only be used inside a coroutine function declared with async def.
Coroutine functions are intended to be run inside a compatible event loop, such as the asyncio loop.
备注
在 3.5.2 版更改: Starting with CPython 3.5.2, __aiter__
can directly return asynchronous iterators. Returning an awaitable object will result in a PendingDeprecationWarning.
See more details in the 异步迭代器 documentation section.
参见
PEP 492 — 使用 async 和 await 语法实现协程
PEP 由 Yury Selivanov 撰写并实现
PEP 465 - 用于矩阵乘法的专用中缀运算符
PEP 465 adds the @
infix operator for matrix multiplication. Currently, no builtin Python types implement the new operator, however, it can be implemented by defining __matmul__()
, __rmatmul__()
, and __imatmul__()
for regular, reflected, and in-place matrix multiplication. The semantics of these methods is similar to that of methods defining other infix arithmetic operators.
矩阵乘法在数学,科学,工程学的许多领域中是一种常见的操作,使用 @
运算符可以编写更简洁的代码:
S = (H @ beta - r).T @ inv(H @ V @ H.T) @ (H @ beta - r)
代替:
S = dot((dot(H, beta) - r).T,
dot(inv(dot(dot(H, V), H.T)), dot(H, beta) - r))
NumPy 1.10 支持新的运算符:
>>> import numpy
>>> x = numpy.ones(3)
>>> x
array([ 1., 1., 1.])
>>> m = numpy.eye(3)
>>> m
array([[ 1., 0., 0.],
[ 0., 1., 0.],
[ 0., 0., 1.]])
>>> x @ m
array([ 1., 1., 1.])
参见
PEP 465 — 用于矩阵乘法的专用中缀运算符
PEP 由 Nathaniel J. Smith 撰写,由 Benjamin Peterson 实现。
PEP 448 - Additional Unpacking Generalizations
PEP 448 extends the allowed uses of the *
iterable unpacking operator and **
dictionary unpacking operator. It is now possible to use an arbitrary number of unpackings in function calls:
>>> print(*[1], *[2], 3, *[4, 5])
1 2 3 4 5
>>> def fn(a, b, c, d):
... print(a, b, c, d)
...
>>> fn(**{'a': 1, 'c': 3}, **{'b': 2, 'd': 4})
1 2 3 4
Similarly, tuple, list, set, and dictionary displays allow multiple unpackings (see 表达式列表 and 字典显示):
>>> *range(4), 4
(0, 1, 2, 3, 4)
>>> [*range(4), 4]
[0, 1, 2, 3, 4]
>>> {*range(4), 4, *(5, 6, 7)}
{0, 1, 2, 3, 4, 5, 6, 7}
>>> {'x': 1, **{'y': 2}}
{'x': 1, 'y': 2}
参见
PEP 448 — Additional Unpacking Generalizations
PEP 由 Joshua Landau 撰写 ,由 Neil Girdhar,Thomas Wouters 和 Joshua Landau 实现。
PEP 461 - percent formatting support for bytes and bytearray
PEP 461 adds support for the %
interpolation operator to bytes and bytearray.
While interpolation is usually thought of as a string operation, there are cases where interpolation on bytes
or bytearrays
makes sense, and the work needed to make up for this missing functionality detracts from the overall readability of the code. This issue is particularly important when dealing with wire format protocols, which are often a mixture of binary and ASCII compatible text.
示例:
>>> b'Hello %b!' % b'World'
b'Hello World!'
>>> b'x=%i y=%f' % (1, 2.5)
b'x=1 y=2.500000'
Unicode is not allowed for %b
, but it is accepted by %a
(equivalent of repr(obj).encode('ascii', 'backslashreplace')
):
>>> b'Hello %b!' % 'World'
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
TypeError: %b requires bytes, or an object that implements __bytes__, not 'str'
>>> b'price: %a' % '10€'
b"price: '10\\u20ac'"
Note that %s
and %r
conversion types, although supported, should only be used in codebases that need compatibility with Python 2.
参见
PEP 461 — Adding % formatting to bytes and bytearray
PEP 由 Ethan Furman 撰写 ,由 Neil Schemenauer 和 Ethan Furman 实现。
PEP 484 —— 类型注解
Function annotation syntax has been a Python feature since version 3.0 (PEP 3107), however the semantics of annotations has been left undefined.
Experience has shown that the majority of function annotation uses were to provide type hints to function parameters and return values. It became evident that it would be beneficial for Python users, if the standard library included the base definitions and tools for type annotations.
PEP 484 introduces a provisional module to provide these standard definitions and tools, along with some conventions for situations where annotations are not available.
For example, here is a simple function whose argument and return type are declared in the annotations:
def greeting(name: str) -> str:
return 'Hello ' + name
While these annotations are available at runtime through the usual __annotations__
attribute, no automatic type checking happens at runtime. Instead, it is assumed that a separate off-line type checker (e.g. mypy) will be used for on-demand source code analysis.
The type system supports unions, generic types, and a special type named Any which is consistent with (i.e. assignable to and from) all types.
参见
typing 模块文档
PEP 484 —— 类型注解
PEP 由 Guido van Rossum,Jukka Lehtosalo 和 Łukasz Langa 撰写,由 Guido van Rossum 实现。
PEP 483 — 类型提示理论
PEP 由 Yury Selivanov 撰写
PEP 471 - os.scandir() function — a better and faster directory iterator
PEP 471 adds a new directory iteration function, os.scandir(), to the standard library. Additionally, os.walk() is now implemented using scandir
, which makes it 3 to 5 times faster on POSIX systems and 7 to 20 times faster on Windows systems. This is largely achieved by greatly reducing the number of calls to os.stat() required to walk a directory tree.
Additionally, scandir
returns an iterator, as opposed to returning a list of file names, which improves memory efficiency when iterating over very large directories.
The following example shows a simple use of os.scandir() to display all the files (excluding directories) in the given path that don’t start with '.'
. The entry.is_file() call will generally not make an additional system call:
for entry in os.scandir(path):
if not entry.name.startswith('.') and entry.is_file():
print(entry.name)
参见
PEP 471 — os.scandir() function — a better and faster directory iterator
PEP 由 Ben Hoyt 在 Victor Stinner 的帮助下撰写并实现
PEP 475: Retry system calls failing with EINTR
An errno.EINTR error code is returned whenever a system call, that is waiting for I/O, is interrupted by a signal. Previously, Python would raise InterruptedError in such cases. This meant that, when writing a Python application, the developer had two choices:
Ignore the
InterruptedError
.Handle the
InterruptedError
and attempt to restart the interrupted system call at every call site.
The first option makes an application fail intermittently. The second option adds a large amount of boilerplate that makes the code nearly unreadable. Compare:
print("Hello World")
和:
while True:
try:
print("Hello World")
break
except InterruptedError:
continue
PEP 475 implements automatic retry of system calls on EINTR
. This removes the burden of dealing with EINTR
or InterruptedError in user code in most situations and makes Python programs, including the standard library, more robust. Note that the system call is only retried if the signal handler does not raise an exception.
Below is a list of functions which are now retried when interrupted by a signal:
faulthandler 模块的功能
os 函数: fchdir(), fchmod(), fchown(), fdatasync(), fstat(), fstatvfs(), fsync(), ftruncate(), mkfifo(), mknod(), open(), posix_fadvise(), posix_fallocate(), pread(), pwrite(), read(), readv(), sendfile(), wait3(), wait4(), wait(), waitid(), waitpid(), write(), writev();
特例: os.close() 和 os.dup2() 现在会忽略 EINTR 错误; 不重试系统调用(请参阅PEP了解基本原理)
select 函数: devpoll.poll(), epoll.poll(), kqueue.control(), poll.poll(), select();
socket 类的方法: accept(), connect() (除了非阻塞套接字), recv(), recvfrom(), recvmsg(), send(), sendall(), sendmsg(), sendto();
参见
PEP 475 — Retry system calls failing with EINTR
PEP and implementation written by Charles-François Natali and Victor Stinner, with the help of Antoine Pitrou (the French connection).
PEP 479: Change StopIteration handling inside generators
The interaction of generators and StopIteration in Python 3.4 and earlier was sometimes surprising, and could conceal obscure bugs. Previously, StopIteration
raised accidentally inside a generator function was interpreted as the end of the iteration by the loop construct driving the generator.
PEP 479 changes the behavior of generators: when a StopIteration
exception is raised inside a generator, it is replaced with a RuntimeError before it exits the generator frame. The main goal of this change is to ease debugging in the situation where an unguarded next() call raises StopIteration
and causes the iteration controlled by the generator to terminate silently. This is particularly pernicious in combination with the yield from
construct.
This is a backwards incompatible change, so to enable the new behavior, a __future__ import is necessary:
>>> from __future__ import generator_stop
>>> def gen():
... next(iter([]))
... yield
...
>>> next(gen())
Traceback (most recent call last):
File "<stdin>", line 2, in gen
StopIteration
The above exception was the direct cause of the following exception:
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
RuntimeError: generator raised StopIteration
Without a __future__
import, a PendingDeprecationWarning will be raised whenever a StopIteration exception is raised inside a generator.
参见
PEP 479 — Change StopIteration handling inside generators
PEP 由 Chris Angelico 和 Guido van Rossum 撰写,由 Chris Angelico,Yury Selivanov 和 Nick Coghlan 实现。
PEP 485: A function for testing approximate equality
PEP 485 adds the math.isclose() and cmath.isclose() functions which tell whether two values are approximately equal or “close” to each other. Whether or not two values are considered close is determined according to given absolute and relative tolerances. Relative tolerance is the maximum allowed difference between isclose
arguments, relative to the larger absolute value:
>>> import math
>>> a = 5.0
>>> b = 4.99998
>>> math.isclose(a, b, rel_tol=1e-5)
True
>>> math.isclose(a, b, rel_tol=1e-6)
False
It is also possible to compare two values using absolute tolerance, which must be a non-negative value:
>>> import math
>>> a = 5.0
>>> b = 4.99998
>>> math.isclose(a, b, abs_tol=0.00003)
True
>>> math.isclose(a, b, abs_tol=0.00001)
False
参见
PEP 485 —— 用于测试近似相等的函数
PEP 由 Christopher Barker 撰写,由 Chris Barker 和 Tal Einat 实现。
PEP 486: Make the Python Launcher aware of virtual environments
PEP 486 makes the Windows launcher (see PEP 397) aware of an active virtual environment. When the default interpreter would be used and the VIRTUAL_ENV
environment variable is set, the interpreter in the virtual environment will be used.
参见
PEP 486 — Make the Python Launcher aware of virtual environments
PEP 由 Paul Moore 撰写并实现
PEP 488: Elimination of PYO files
PEP 488 does away with the concept of .pyo
files. This means that .pyc
files represent both unoptimized and optimized bytecode. To prevent the need to constantly regenerate bytecode files, .pyc
files now have an optional opt-
tag in their name when the bytecode is optimized. This has the side-effect of no more bytecode file name clashes when running under either -O or -OO. Consequently, bytecode files generated from -O, and -OO may now exist simultaneously. importlib.util.cache_from_source() has an updated API to help with this change.
参见
PEP 488 — Elimination of PYO files
PEP 由 Brett Cannon 撰写并实现。
PEP 489: Multi-phase extension module initialization
PEP 489 updates extension module initialization to take advantage of the two step module loading mechanism introduced by PEP 451 in Python 3.4.
This change brings the import semantics of extension modules that opt-in to using the new mechanism much closer to those of Python source and bytecode modules, including the ability to use any valid identifier as a module name, rather than being restricted to ASCII.
参见
PEP 489 — Multi-phase extension module initialization
PEP 由 Petr Viktorin , Stefan Behnel 和 Nick Coghlan 撰写,由 Petr Viktorin 实现。
其他语言特性修改
对Python 语言核心进行的小改动:
Added the
"namereplace"
error handlers. The"backslashreplace"
error handlers now work with decoding and translating. (Contributed by Serhiy Storchaka in bpo-19676 and bpo-22286.)The -b option now affects comparisons of bytes with int. (Contributed by Serhiy Storchaka in bpo-23681.)
New Kazakh
kz1048
and Tajikkoi8_t
codecs. (Contributed by Serhiy Storchaka in bpo-22682 and bpo-22681.)Property docstrings are now writable. This is especially useful for collections.namedtuple() docstrings. (Contributed by Berker Peksag in bpo-24064.)
Circular imports involving relative imports are now supported. (Contributed by Brett Cannon and Antoine Pitrou in bpo-17636.)
新增模块
typing
The new typing provisional module provides standard definitions and tools for function type annotations. See Type Hints for more information.
zipapp
The new zipapp module (specified in PEP 441) provides an API and command line tool for creating executable Python Zip Applications, which were introduced in Python 2.6 in bpo-1739468, but which were not well publicized, either at the time or since.
With the new module, bundling your application is as simple as putting all the files, including a __main__.py
file, into a directory myapp
and running:
$ python -m zipapp myapp
$ python myapp.pyz
The module implementation has been contributed by Paul Moore in bpo-23491.
参见
PEP 441 — Improving Python ZIP Application Support
改进的模块
argparse
The ArgumentParser class now allows disabling abbreviated usage of long options by setting allow_abbrev to False
. (Contributed by Jonathan Paugh, Steven Bethard, paul j3 and Daniel Eriksson in bpo-14910.)
asyncio
Since the asyncio module is provisional, all changes introduced in Python 3.5 have also been backported to Python 3.4.x.
Notable changes in the asyncio module since Python 3.4.0:
New debugging APIs: loop.set_debug() and loop.get_debug() methods. (Contributed by Victor Stinner.)
The proactor event loop now supports SSL. (Contributed by Antoine Pitrou and Victor Stinner in bpo-22560.)
A new loop.is_closed() method to check if the event loop is closed. (Contributed by Victor Stinner in bpo-21326.)
A new loop.create_task() to conveniently create and schedule a new Task for a coroutine. The
create_task
method is also used by all asyncio functions that wrap coroutines into tasks, such as asyncio.wait(), asyncio.gather(), etc. (Contributed by Victor Stinner.)A new transport.get_write_buffer_limits() method to inquire for high- and low- water limits of the flow control. (Contributed by Victor Stinner.)
The
async()
function is deprecated in favor of ensure_future(). (Contributed by Yury Selivanov.)New loop.set_task_factory() and loop.get_task_factory() methods to customize the task factory that loop.create_task() method uses. (Contributed by Yury Selivanov.)
New Queue.join() and Queue.task_done() queue methods. (Contributed by Victor Stinner.)
The
JoinableQueue
class was removed, in favor of the asyncio.Queue class. (Contributed by Victor Stinner.)
3.5.1 中的更新:
The ensure_future() function and all functions that use it, such as loop.run_until_complete(), now accept all kinds of awaitable objects. (Contributed by Yury Selivanov.)
新增 run_coroutine_threadsafe() 函数用于从其他线程向事件循环提交协程。(由 Vincent Michel 贡献。)
新增 Transport.is_closing() 方法用于检查传输是否正在关闭或已经关闭。 (由 Yury Selivanov 贡献。)
loop.create_server() 方法现在可以接受一个主机列表。 (由 Yann Sionneau 贡献。)
3.5.2 中的更新:
New loop.create_future() method to create Future objects. This allows alternative event loop implementations, such as uvloop, to provide a faster asyncio.Future implementation. (Contributed by Yury Selivanov.)
New loop.get_exception_handler() method to get the current exception handler. (Contributed by Yury Selivanov.)
New StreamReader.readuntil() method to read data from the stream until a separator bytes sequence appears. (Contributed by Mark Korenberg.)
The loop.create_connection() and loop.create_server() methods are optimized to avoid calling the system
getaddrinfo
function if the address is already resolved. (Contributed by A. Jesse Jiryu Davis.)The loop.sock_connect(sock, address) no longer requires the address to be resolved prior to the call. (Contributed by A. Jesse Jiryu Davis.)
bz2
The BZ2Decompressor.decompress method now accepts an optional max_length argument to limit the maximum size of decompressed data. (Contributed by Nikolaus Rath in bpo-15955.)
cgi
The FieldStorage
class now supports the context manager protocol. (Contributed by Berker Peksag in bpo-20289.)
cmath
A new function isclose() provides a way to test for approximate equality. (Contributed by Chris Barker and Tal Einat in bpo-24270.)
code
The InteractiveInterpreter.showtraceback() method now prints the full chained traceback, just like the interactive interpreter. (Contributed by Claudiu Popa in bpo-17442.)
collections
The OrderedDict class is now implemented in C, which makes it 4 to 100 times faster. (Contributed by Eric Snow in bpo-16991.)
OrderedDict.items()
, OrderedDict.keys()
, OrderedDict.values()
views now support reversed() iteration. (Contributed by Serhiy Storchaka in bpo-19505.)
The deque class now defines index(), insert(), and copy(), and supports the +
and *
operators. This allows deques to be recognized as a MutableSequence and improves their substitutability for lists. (Contributed by Raymond Hettinger in bpo-23704.)
Docstrings produced by namedtuple() can now be updated:
Point = namedtuple('Point', ['x', 'y'])
Point.__doc__ += ': Cartesian coodinate'
Point.x.__doc__ = 'abscissa'
Point.y.__doc__ = 'ordinate'
(由 Berker Peksag 在 bpo-24064 中贡献。)
The UserString class now implements the __getnewargs__()
, __rmod__()
, casefold(), format_map(), isprintable(), and maketrans() methods to match the corresponding methods of str. (Contributed by Joe Jevnik in bpo-22189.)
collections.abc
The Sequence.index()
method now accepts start and stop arguments to match the corresponding methods of tuple, list, etc. (Contributed by Devin Jeanpierre in bpo-23086.)
A new Generator abstract base class. (Contributed by Stefan Behnel in bpo-24018.)
New Awaitable, Coroutine, AsyncIterator, and AsyncIterable abstract base classes. (Contributed by Yury Selivanov in bpo-24184.)
For earlier Python versions, a backport of the new ABCs is available in an external PyPI package.
compileall
A new compileall option, -j *N*
, allows running N workers simultaneously to perform parallel bytecode compilation. The compile_dir() function has a corresponding workers
parameter. (Contributed by Claudiu Popa in bpo-16104.)
Another new option, -r
, allows controlling the maximum recursion level for subdirectories. (Contributed by Claudiu Popa in bpo-19628.)
The -q
command line option can now be specified more than once, in which case all output, including errors, will be suppressed. The corresponding quiet
parameter in compile_dir(), compile_file(), and compile_path() can now accept an integer value indicating the level of output suppression. (Contributed by Thomas Kluyver in bpo-21338.)
concurrent.futures
The Executor.map() method now accepts a chunksize argument to allow batching of tasks to improve performance when ProcessPoolExecutor() is used. (Contributed by Dan O’Reilly in bpo-11271.)
The number of workers in the ThreadPoolExecutor constructor is optional now. The default value is 5 times the number of CPUs. (Contributed by Claudiu Popa in bpo-21527.)
configparser
configparser now provides a way to customize the conversion of values by specifying a dictionary of converters in the ConfigParser constructor, or by defining them as methods in ConfigParser
subclasses. Converters defined in a parser instance are inherited by its section proxies.
示例:
>>> import configparser
>>> conv = {}
>>> conv['list'] = lambda v: [e.strip() for e in v.split() if e.strip()]
>>> cfg = configparser.ConfigParser(converters=conv)
>>> cfg.read_string("""
... [s]
... list = a b c d e f g
... """)
>>> cfg.get('s', 'list')
'a b c d e f g'
>>> cfg.getlist('s', 'list')
['a', 'b', 'c', 'd', 'e', 'f', 'g']
>>> section = cfg['s']
>>> section.getlist('list')
['a', 'b', 'c', 'd', 'e', 'f', 'g']
(由 Łukasz Langa 在 bpo-18159 中贡献。)
contextlib
The new redirect_stderr() context manager (similar to redirect_stdout()) makes it easier for utility scripts to handle inflexible APIs that write their output to sys.stderr and don’t provide any options to redirect it:
>>> import contextlib, io, logging
>>> f = io.StringIO()
>>> with contextlib.redirect_stderr(f):
... logging.warning('warning')
...
>>> f.getvalue()
'WARNING:root:warning\n'
(由 Berker Peksag 在 bpo-22389 中贡献。)
csv
The writerow() method now supports arbitrary iterables, not just sequences. (Contributed by Serhiy Storchaka in bpo-23171.)
curses
The new update_lines_cols() function updates the LINES
and COLS
environment variables. This is useful for detecting manual screen resizing. (Contributed by Arnon Yaari in bpo-4254.)
dbm
dumb.open always creates a new database when the flag has the value "n"
. (Contributed by Claudiu Popa in bpo-18039.)
difflib
The charset of HTML documents generated by HtmlDiff.make_file() can now be customized by using a new charset keyword-only argument. The default charset of HTML document changed from "ISO-8859-1"
to "utf-8"
. (Contributed by Berker Peksag in bpo-2052.)
The diff_bytes() function can now compare lists of byte strings. This fixes a regression from Python 2. (Contributed by Terry J. Reedy and Greg Ward in bpo-17445.)
distutils
Both the build
and build_ext
commands now accept a -j
option to enable parallel building of extension modules. (Contributed by Antoine Pitrou in bpo-5309.)
The distutils module now supports xz
compression, and can be enabled by passing xztar
as an argument to bdist --format
. (Contributed by Serhiy Storchaka in bpo-16314.)
doctest
The DocTestSuite() function returns an empty unittest.TestSuite if module contains no docstrings, instead of raising ValueError. (Contributed by Glenn Jones in bpo-15916.)
A new policy option Policy.mangle_from_ controls whether or not lines that start with "From "
in email bodies are prefixed with a ">"
character by generators. The default is True
for compat32 and False
for all other policies. (Contributed by Milan Oberkirch in bpo-20098.)
A new Message.get_content_disposition() method provides easy access to a canonical value for the Content-Disposition header. (Contributed by Abhilash Raj in bpo-21083.)
A new policy option EmailPolicy.utf8 can be set to True
to encode email headers using the UTF-8 charset instead of using encoded words. This allows Messages
to be formatted according to RFC 6532 and used with an SMTP server that supports the RFC 6531 SMTPUTF8
extension. (Contributed by R. David Murray in bpo-24211.)
The mime.text.MIMEText constructor now accepts a charset.Charset instance. (Contributed by Claude Paroz and Berker Peksag in bpo-16324.)
enum
The Enum callable has a new parameter start to specify the initial number of enum values if only names are provided:
>>> Animal = enum.Enum('Animal', 'cat dog', start=10)
>>> Animal.cat
<Animal.cat: 10>
>>> Animal.dog
<Animal.dog: 11>
(由 Ethan Furman 在 bpo-21706 中贡献。)
faulthandler
The enable(), register(), dump_traceback() and dump_traceback_later() functions now accept file descriptors in addition to file-like objects. (Contributed by Wei Wu in bpo-23566.)
functools
Most of the lru_cache() machinery is now implemented in C, making it significantly faster. (Contributed by Matt Joiner, Alexey Kachayev, and Serhiy Storchaka in bpo-14373.)
glob
The iglob() and glob() functions now support recursive search in subdirectories, using the "**"
pattern. (Contributed by Serhiy Storchaka in bpo-13968.)
gzip
The mode argument of the GzipFile constructor now accepts "x"
to request exclusive creation. (Contributed by Tim Heaney in bpo-19222.)
heapq
Element comparison in merge() can now be customized by passing a key function in a new optional key keyword argument, and a new optional reverse keyword argument can be used to reverse element comparison:
>>> import heapq
>>> a = ['9', '777', '55555']
>>> b = ['88', '6666']
>>> list(heapq.merge(a, b, key=len))
['9', '88', '777', '6666', '55555']
>>> list(heapq.merge(reversed(a), reversed(b), key=len, reverse=True))
['55555', '6666', '777', '88', '9']
(由 Raymond Hettinger 在 bpo-13742 中贡献。)
http
A new HTTPStatus enum that defines a set of HTTP status codes, reason phrases and long descriptions written in English. (Contributed by Demian Brecht in bpo-21793.)
http.client
HTTPConnection.getresponse() now raises a RemoteDisconnected exception when a remote server connection is closed unexpectedly. Additionally, if a ConnectionError (of which RemoteDisconnected
is a subclass) is raised, the client socket is now closed automatically, and will reconnect on the next request:
import http.client
conn = http.client.HTTPConnection('www.python.org')
for retries in range(3):
try:
conn.request('GET', '/')
resp = conn.getresponse()
except http.client.RemoteDisconnected:
pass
(由 Martin Panter 在 bpo-3566 中贡献。)
idlelib 与 IDLE
Since idlelib implements the IDLE shell and editor and is not intended for import by other programs, it gets improvements with every release. See Lib/idlelib/NEWS.txt
for a cumulative list of changes since 3.4.0, as well as changes made in future 3.5.x releases. This file is also available from the IDLE Help ‣ About IDLE dialog.
imaplib
The IMAP4 class now supports the context manager protocol. When used in a with statement, the IMAP4 LOGOUT
command will be called automatically at the end of the block. (Contributed by Tarek Ziadé and Serhiy Storchaka in bpo-4972.)
The imaplib module now supports RFC 5161 (ENABLE Extension) and RFC 6855 (UTF-8 Support) via the IMAP4.enable() method. A new IMAP4.utf8_enabled attribute tracks whether or not RFC 6855 support is enabled. (Contributed by Milan Oberkirch, R. David Murray, and Maciej Szulik in bpo-21800.)
The imaplib module now automatically encodes non-ASCII string usernames and passwords using UTF-8, as recommended by the RFCs. (Contributed by Milan Oberkirch in bpo-21800.)
imghdr
The what() function now recognizes the OpenEXR format (contributed by Martin Vignali and Claudiu Popa in bpo-20295), and the WebP format (contributed by Fabrice Aneche and Claudiu Popa in bpo-20197.)
importlib
The util.LazyLoader class allows for lazy loading of modules in applications where startup time is important. (Contributed by Brett Cannon in bpo-17621.)
The abc.InspectLoader.source_to_code() method is now a static method. This makes it easier to initialize a module object with code compiled from a string by running exec(code, module.__dict__)
. (Contributed by Brett Cannon in bpo-21156.)
The new util.module_from_spec() function is now the preferred way to create a new module. As opposed to creating a types.ModuleType instance directly, this new function will set the various import-controlled attributes based on the passed-in spec object. (Contributed by Brett Cannon in bpo-20383.)
inspect
Both the Signature and Parameter classes are now picklable and hashable. (Contributed by Yury Selivanov in bpo-20726 and bpo-20334.)
A new BoundArguments.apply_defaults() method provides a way to set default values for missing arguments:
>>> def foo(a, b='ham', *args): pass
>>> ba = inspect.signature(foo).bind('spam')
>>> ba.apply_defaults()
>>> ba.arguments
OrderedDict([('a', 'spam'), ('b', 'ham'), ('args', ())])
(由 Yury Selivanov 在 bpo-24190 中贡献。)
A new class method Signature.from_callable() makes subclassing of Signature easier. (Contributed by Yury Selivanov and Eric Snow in bpo-17373.)
The signature() function now accepts a follow_wrapped optional keyword argument, which, when set to False
, disables automatic following of __wrapped__
links. (Contributed by Yury Selivanov in bpo-20691.)
A set of new functions to inspect coroutine functions and coroutine objects has been added: iscoroutine(), iscoroutinefunction(), isawaitable(), getcoroutinelocals(), and getcoroutinestate(). (Contributed by Yury Selivanov in bpo-24017 and bpo-24400.)
The stack(), trace(), getouterframes(), and getinnerframes() functions now return a list of named tuples. (Contributed by Daniel Shahaf in bpo-16808.)
io
A new BufferedIOBase.readinto1() method, that uses at most one call to the underlying raw stream’s RawIOBase.read() or RawIOBase.readinto() methods. (Contributed by Nikolaus Rath in bpo-20578.)
ipaddress
Both the IPv4Network and IPv6Network classes now accept an (address, netmask)
tuple argument, so as to easily construct network objects from existing addresses:
>>> import ipaddress
>>> ipaddress.IPv4Network(('127.0.0.0', 8))
IPv4Network('127.0.0.0/8')
>>> ipaddress.IPv4Network(('127.0.0.0', '255.0.0.0'))
IPv4Network('127.0.0.0/8')
(由 Peter Moody 和 Antoine Pitrou 在 bpo-16531 中贡献。)
A new reverse_pointer
attribute for the IPv4Network and IPv6Network classes returns the name of the reverse DNS PTR record:
>>> import ipaddress
>>> addr = ipaddress.IPv4Address('127.0.0.1')
>>> addr.reverse_pointer
'1.0.0.127.in-addr.arpa'
>>> addr6 = ipaddress.IPv6Address('::1')
>>> addr6.reverse_pointer
'1.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.ip6.arpa'
(由 Leon Weber 在 bpo-20480 中贡献。)
json
The json.tool command line interface now preserves the order of keys in JSON objects passed in input. The new --sort-keys
option can be used to sort the keys alphabetically. (Contributed by Berker Peksag in bpo-21650.)
JSON decoder now raises JSONDecodeError instead of ValueError to provide better context information about the error. (Contributed by Serhiy Storchaka in bpo-19361.)
linecache
A new lazycache() function can be used to capture information about a non-file-based module to permit getting its lines later via getline(). This avoids doing I/O until a line is actually needed, without having to carry the module globals around indefinitely. (Contributed by Robert Collins in bpo-17911.)
locale
A new delocalize() function can be used to convert a string into a normalized number string, taking the LC_NUMERIC
settings into account:
>>> import locale
>>> locale.setlocale(locale.LC_NUMERIC, 'de_DE.UTF-8')
'de_DE.UTF-8'
>>> locale.delocalize('1.234,56')
'1234.56'
>>> locale.setlocale(locale.LC_NUMERIC, 'en_US.UTF-8')
'en_US.UTF-8'
>>> locale.delocalize('1,234.56')
'1234.56'
(由 Cédric Krier 在 bpo-13918 中贡献。)
logging
All logging methods (Logger log(), exception(), critical(), debug(), etc.), now accept exception instances as an exc_info argument, in addition to boolean values and exception tuples:
>>> import logging
>>> try:
... 1/0
... except ZeroDivisionError as ex:
... logging.error('exception', exc_info=ex)
ERROR:root:exception
(由 Yury Selivanov 在 bpo-20537 中贡献。)
The handlers.HTTPHandler class now accepts an optional ssl.SSLContext instance to configure SSL settings used in an HTTP connection. (Contributed by Alex Gaynor in bpo-22788.)
The handlers.QueueListener class now takes a respect_handler_level keyword argument which, if set to True
, will pass messages to handlers taking handler levels into account. (Contributed by Vinay Sajip.)
lzma
The LZMADecompressor.decompress() method now accepts an optional max_length argument to limit the maximum size of decompressed data. (Contributed by Martin Panter in bpo-15955.)
math
Two new constants have been added to the math module: inf and nan. (Contributed by Mark Dickinson in bpo-23185.)
A new function isclose() provides a way to test for approximate equality. (Contributed by Chris Barker and Tal Einat in bpo-24270.)
A new gcd() function has been added. The fractions.gcd()
function is now deprecated. (Contributed by Mark Dickinson and Serhiy Storchaka in bpo-22486.)
multiprocessing
sharedctypes.synchronized() objects now support the context manager protocol. (Contributed by Charles-François Natali in bpo-21565.)
operator
attrgetter(), itemgetter(), and methodcaller() objects now support pickling. (Contributed by Josh Rosenberg and Serhiy Storchaka in bpo-22955.)
New matmul() and imatmul() functions to perform matrix multiplication. (Contributed by Benjamin Peterson in bpo-21176.)
os
The new scandir() function returning an iterator of DirEntry objects has been added. If possible, scandir() extracts file attributes while scanning a directory, removing the need to perform subsequent system calls to determine file type or attributes, which may significantly improve performance. (Contributed by Ben Hoyt with the help of Victor Stinner in bpo-22524.)
On Windows, a new stat_result.st_file_attributes attribute is now available. It corresponds to the dwFileAttributes
member of the BY_HANDLE_FILE_INFORMATION
structure returned by GetFileInformationByHandle()
. (Contributed by Ben Hoyt in bpo-21719.)
The urandom() function now uses the getrandom()
syscall on Linux 3.17 or newer, and getentropy()
on OpenBSD 5.6 and newer, removing the need to use /dev/urandom
and avoiding failures due to potential file descriptor exhaustion. (Contributed by Victor Stinner in bpo-22181.)
New get_blocking() and set_blocking() functions allow getting and setting a file descriptor’s blocking mode (O_NONBLOCK.) (Contributed by Victor Stinner in bpo-22054.)
The truncate() and ftruncate() functions are now supported on Windows. (Contributed by Steve Dower in bpo-23668.)
There is a new os.path.commonpath() function returning the longest common sub-path of each passed pathname. Unlike the os.path.commonprefix() function, it always returns a valid path:
>>> os.path.commonprefix(['/usr/lib', '/usr/local/lib'])
'/usr/l'
>>> os.path.commonpath(['/usr/lib', '/usr/local/lib'])
'/usr'
(由 Rafik Draoui 和 Serhiy Storchaka 在 bpo-10395 中贡献。)
pathlib
The new Path.samefile() method can be used to check whether the path points to the same file as another path, which can be either another Path object, or a string:
>>> import pathlib
>>> p1 = pathlib.Path('/etc/hosts')
>>> p2 = pathlib.Path('/etc/../etc/hosts')
>>> p1.samefile(p2)
True
(由 Vajrasky Kok 和 Antoine Pitrou 在 bpo-19775 中贡献。)
The Path.mkdir() method now accepts a new optional exist_ok argument to match mkdir -p
and os.makedirs() functionality. (Contributed by Berker Peksag in bpo-21539.)
There is a new Path.expanduser() method to expand ~
and ~user
prefixes. (Contributed by Serhiy Storchaka and Claudiu Popa in bpo-19776.)
A new Path.home() class method can be used to get a Path instance representing the user’s home directory. (Contributed by Victor Salgado and Mayank Tripathi in bpo-19777.)
New Path.write_text(), Path.read_text(), Path.write_bytes(), Path.read_bytes() methods to simplify read/write operations on files.
The following code snippet will create or rewrite existing file ~/spam42
:
>>> import pathlib
>>> p = pathlib.Path('~/spam42')
>>> p.expanduser().write_text('ham')
3
(由 Christopher Welborn 在 bpo-20218 中贡献。)
pickle
Nested objects, such as unbound methods or nested classes, can now be pickled using pickle protocols older than protocol version 4. Protocol version 4 already supports these cases. (Contributed by Serhiy Storchaka in bpo-23611.)
poplib
A new POP3.utf8() command enables RFC 6856 (Internationalized Email) support, if a POP server supports it. (Contributed by Milan OberKirch in bpo-21804.)
re
References and conditional references to groups with fixed length are now allowed in lookbehind assertions:
>>> import re
>>> pat = re.compile(r'(a|b).(?<=\1)c')
>>> pat.match('aac')
<_sre.SRE_Match object; span=(0, 3), match='aac'>
>>> pat.match('bbc')
<_sre.SRE_Match object; span=(0, 3), match='bbc'>
(由 Serhiy Storchaka 在 bpo-9179 中贡献。)
The number of capturing groups in regular expressions is no longer limited to 100. (Contributed by Serhiy Storchaka in bpo-22437.)
The sub() and subn() functions now replace unmatched groups with empty strings instead of raising an exception. (Contributed by Serhiy Storchaka in bpo-1519638.)
The re.error exceptions have new attributes, msg, pattern, pos, lineno, and colno, that provide better context information about the error:
>>> re.compile("""
... (?x)
... .++
... """)
Traceback (most recent call last):
...
sre_constants.error: multiple repeat at position 16 (line 3, column 7)
(由 Serhiy Storchaka 在 bpo-22578 中贡献。)
readline
A new append_history_file() function can be used to append the specified number of trailing elements in history to the given file. (Contributed by Bruno Cauet in bpo-22940.)
selectors
The new DevpollSelector supports efficient /dev/poll
polling on Solaris. (Contributed by Giampaolo Rodola’ in bpo-18931.)
shutil
The move() function now accepts a copy_function argument, allowing, for example, the copy() function to be used instead of the default copy2() if there is a need to ignore file metadata when moving. (Contributed by Claudiu Popa in bpo-19840.)
The make_archive() function now supports the xztar format. (Contributed by Serhiy Storchaka in bpo-5411.)
signal
On Windows, the set_wakeup_fd() function now also supports socket handles. (Contributed by Victor Stinner in bpo-22018.)
Various SIG*
constants in the signal module have been converted into Enums. This allows meaningful names to be printed during debugging, instead of integer “magic numbers”. (Contributed by Giampaolo Rodola’ in bpo-21076.)
smtpd
Both the SMTPServer and SMTPChannel classes now accept a decode_data keyword argument to determine if the DATA
portion of the SMTP transaction is decoded using the "utf-8"
codec or is instead provided to the SMTPServer.process_message() method as a byte string. The default is True
for backward compatibility reasons, but will change to False
in Python 3.6. If decode_data is set to False
, the process_message
method must be prepared to accept keyword arguments. (Contributed by Maciej Szulik in bpo-19662.)
The SMTPServer class now advertises the 8BITMIME
extension (RFC 6152) if decode_data has been set True
. If the client specifies BODY=8BITMIME
on the MAIL
command, it is passed to SMTPServer.process_message() via the mail_options keyword. (Contributed by Milan Oberkirch and R. David Murray in bpo-21795.)
The SMTPServer class now also supports the SMTPUTF8
extension (RFC 6531: Internationalized Email). If the client specified SMTPUTF8 BODY=8BITMIME
on the MAIL
command, they are passed to SMTPServer.process_message() via the mail_options keyword. It is the responsibility of the process_message
method to correctly handle the SMTPUTF8
data. (Contributed by Milan Oberkirch in bpo-21725.)
It is now possible to provide, directly or via name resolution, IPv6 addresses in the SMTPServer constructor, and have it successfully connect. (Contributed by Milan Oberkirch in bpo-14758.)
smtplib
A new SMTP.auth() method provides a convenient way to implement custom authentication mechanisms. (Contributed by Milan Oberkirch in bpo-15014.)
The SMTP.set_debuglevel() method now accepts an additional debuglevel (2), which enables timestamps in debug messages. (Contributed by Gavin Chappell and Maciej Szulik in bpo-16914.)
Both the SMTP.sendmail() and SMTP.send_message() methods now support RFC 6531 (SMTPUTF8). (Contributed by Milan Oberkirch and R. David Murray in bpo-22027.)
sndhdr
The what() and whathdr() functions now return a namedtuple(). (Contributed by Claudiu Popa in bpo-18615.)
socket
Functions with timeouts now use a monotonic clock, instead of a system clock. (Contributed by Victor Stinner in bpo-22043.)
A new socket.sendfile() method allows sending a file over a socket by using the high-performance os.sendfile() function on UNIX, resulting in uploads being from 2 to 3 times faster than when using plain socket.send(). (Contributed by Giampaolo Rodola’ in bpo-17552.)
The socket.sendall() method no longer resets the socket timeout every time bytes are received or sent. The socket timeout is now the maximum total duration to send all data. (Contributed by Victor Stinner in bpo-23853.)
The backlog argument of the socket.listen() method is now optional. By default it is set to SOMAXCONN or to 128
, whichever is less. (Contributed by Charles-François Natali in bpo-21455.)
ssl
内存 BIO 支持
(由 Geert Jansen 在 bpo-21965 中贡献。)
The new SSLObject class has been added to provide SSL protocol support for cases when the network I/O capabilities of SSLSocket are not necessary or are suboptimal. SSLObject
represents an SSL protocol instance, but does not implement any network I/O methods, and instead provides a memory buffer interface. The new MemoryBIO class can be used to pass data between Python and an SSL protocol instance.
The memory BIO SSL support is primarily intended to be used in frameworks implementing asynchronous I/O for which SSLSocket‘s readiness model (“select/poll”) is inefficient.
A new SSLContext.wrap_bio() method can be used to create a new SSLObject
instance.
Application-Layer Protocol Negotiation Support
(由 Benjamin Peterson 在 bpo-20188 中贡献。)
Where OpenSSL support is present, the ssl module now implements the Application-Layer Protocol Negotiation TLS extension as described in RFC 7301.
The new SSLContext.set_alpn_protocols() can be used to specify which protocols a socket should advertise during the TLS handshake.
The new SSLSocket.selected_alpn_protocol() returns the protocol that was selected during the TLS handshake. The HAS_ALPN flag indicates whether ALPN support is present.
Other Changes
There is a new SSLSocket.version() method to query the actual protocol version in use. (Contributed by Antoine Pitrou in bpo-20421.)
The SSLSocket class now implements a SSLSocket.sendfile()
method. (Contributed by Giampaolo Rodola’ in bpo-17552.)
The SSLSocket.send()
method now raises either the ssl.SSLWantReadError or ssl.SSLWantWriteError exception on a non-blocking socket if the operation would block. Previously, it would return 0
. (Contributed by Nikolaus Rath in bpo-20951.)
The cert_time_to_seconds() function now interprets the input time as UTC and not as local time, per RFC 5280. Additionally, the return value is always an int. (Contributed by Akira Li in bpo-19940.)
New SSLObject.shared_ciphers()
and SSLSocket.shared_ciphers() methods return the list of ciphers sent by the client during the handshake. (Contributed by Benjamin Peterson in bpo-23186.)
The SSLSocket.do_handshake(), SSLSocket.read(), SSLSocket.shutdown()
, and SSLSocket.write() methods of the SSLSocket class no longer reset the socket timeout every time bytes are received or sent. The socket timeout is now the maximum total duration of the method. (Contributed by Victor Stinner in bpo-23853.)
The match_hostname() function now supports matching of IP addresses. (Contributed by Antoine Pitrou in bpo-23239.)
sqlite3
The Row class now fully supports the sequence protocol, in particular reversed() iteration and slice indexing. (Contributed by Claudiu Popa in bpo-10203; by Lucas Sinclair, Jessica McKellar, and Serhiy Storchaka in bpo-13583.)
subprocess
The new run() function has been added. It runs the specified command and returns a CompletedProcess object, which describes a finished process. The new API is more consistent and is the recommended approach to invoking subprocesses in Python code that does not need to maintain compatibility with earlier Python versions. (Contributed by Thomas Kluyver in bpo-23342.)
示例:
>>> subprocess.run(["ls", "-l"]) # doesn't capture output
CompletedProcess(args=['ls', '-l'], returncode=0)
>>> subprocess.run("exit 1", shell=True, check=True)
Traceback (most recent call last):
...
subprocess.CalledProcessError: Command 'exit 1' returned non-zero exit status 1
>>> subprocess.run(["ls", "-l", "/dev/null"], stdout=subprocess.PIPE)
CompletedProcess(args=['ls', '-l', '/dev/null'], returncode=0,
stdout=b'crw-rw-rw- 1 root root 1, 3 Jan 23 16:23 /dev/null\n')
sys
A new set_coroutine_wrapper()
function allows setting a global hook that will be called whenever a coroutine object is created by an async def function. A corresponding get_coroutine_wrapper()
can be used to obtain a currently set wrapper. Both functions are provisional, and are intended for debugging purposes only. (Contributed by Yury Selivanov in bpo-24017.)
A new is_finalizing() function can be used to check if the Python interpreter is shutting down. (Contributed by Antoine Pitrou in bpo-22696.)
sysconfig
The name of the user scripts directory on Windows now includes the first two components of the Python version. (Contributed by Paul Moore in bpo-23437.)
tarfile
The mode argument of the open() function now accepts "x"
to request exclusive creation. (Contributed by Berker Peksag in bpo-21717.)
The TarFile.extractall() and TarFile.extract() methods now take a keyword argument numeric_owner. If set to True
, the extracted files and directories will be owned by the numeric uid
and gid
from the tarfile. If set to False
(the default, and the behavior in versions prior to 3.5), they will be owned by the named user and group in the tarfile. (Contributed by Michael Vogt and Eric Smith in bpo-23193.)
The TarFile.list() now accepts an optional members keyword argument that can be set to a subset of the list returned by TarFile.getmembers(). (Contributed by Serhiy Storchaka in bpo-21549.)
threading
Both the Lock.acquire() and RLock.acquire() methods now use a monotonic clock for timeout management. (Contributed by Victor Stinner in bpo-22043.)
time
The monotonic() function is now always available. (Contributed by Victor Stinner in bpo-22043.)
timeit
A new command line option -u
or --unit=*U*
can be used to specify the time unit for the timer output. Supported options are usec
, msec
, or sec
. (Contributed by Julian Gindi in bpo-18983.)
The timeit() function has a new globals parameter for specifying the namespace in which the code will be running. (Contributed by Ben Roberts in bpo-2527.)
tkinter
The tkinter._fix
module used for setting up the Tcl/Tk environment on Windows has been replaced by a private function in the _tkinter
module which makes no permanent changes to environment variables. (Contributed by Zachary Ware in bpo-20035.)
回溯
New walk_stack() and walk_tb() functions to conveniently traverse frame and traceback objects. (Contributed by Robert Collins in bpo-17911.)
New lightweight classes: TracebackException, StackSummary, and FrameSummary. (Contributed by Robert Collins in bpo-17911.)
Both the print_tb() and print_stack() functions now support negative values for the limit argument. (Contributed by Dmitry Kazakov in bpo-22619.)
types
A new coroutine() function to transform generator and generator-like objects into awaitables. (Contributed by Yury Selivanov in bpo-24017.)
A new type called CoroutineType, which is used for coroutine objects created by async def functions. (Contributed by Yury Selivanov in bpo-24400.)
unicodedata
The unicodedata module now uses data from Unicode 8.0.0.
unittest
The TestLoader.loadTestsFromModule() method now accepts a keyword-only argument pattern which is passed to load_tests
as the third argument. Found packages are now checked for load_tests
regardless of whether their path matches pattern, because it is impossible for a package name to match the default pattern. (Contributed by Robert Collins and Barry A. Warsaw in bpo-16662.)
Unittest discovery errors now are exposed in the TestLoader.errors attribute of the TestLoader instance. (Contributed by Robert Collins in bpo-19746.)
A new command line option --locals
to show local variables in tracebacks. (Contributed by Robert Collins in bpo-22936.)
unittest.mock
The Mock class has the following improvements:
The class constructor has a new unsafe parameter, which causes mock objects to raise AttributeError on attribute names starting with
"assert"
. (Contributed by Kushal Das in bpo-21238.)A new Mock.assert_not_called() method to check if the mock object was called. (Contributed by Kushal Das in bpo-21262.)
The MagicMock class now supports __truediv__()
, __divmod__()
and __matmul__()
operators. (Contributed by Johannes Baiter in bpo-20968, and Håkan Lövdahl in bpo-23581 and bpo-23568.)
It is no longer necessary to explicitly pass create=True
to the patch() function when patching builtin names. (Contributed by Kushal Das in bpo-17660.)
urllib
A new request.HTTPPasswordMgrWithPriorAuth class allows HTTP Basic Authentication credentials to be managed so as to eliminate unnecessary 401
response handling, or to unconditionally send credentials on the first request in order to communicate with servers that return a 404
response instead of a 401
if the Authorization
header is not sent. (Contributed by Matej Cepl in bpo-19494 and Akshit Khurana in bpo-7159.)
A new quote_via argument for the parse.urlencode() function provides a way to control the encoding of query parts if needed. (Contributed by Samwyse and Arnon Yaari in bpo-13866.)
The request.urlopen() function accepts an ssl.SSLContext object as a context argument, which will be used for the HTTPS connection. (Contributed by Alex Gaynor in bpo-22366.)
The parse.urljoin() was updated to use the RFC 3986 semantics for the resolution of relative URLs, rather than RFC 1808 and RFC 2396. (Contributed by Demian Brecht and Senthil Kumaran in bpo-22118.)
wsgiref
The headers argument of the headers.Headers class constructor is now optional. (Contributed by Pablo Torres Navarrete and SilentGhost in bpo-5800.)
xmlrpc
The client.ServerProxy class now supports the context manager protocol. (Contributed by Claudiu Popa in bpo-20627.)
The client.ServerProxy constructor now accepts an optional ssl.SSLContext instance. (Contributed by Alex Gaynor in bpo-22960.)
xml.sax
SAX parsers now support a character stream of the xmlreader.InputSource object. (Contributed by Serhiy Storchaka in bpo-2175.)
parseString() now accepts a str instance. (Contributed by Serhiy Storchaka in bpo-10590.)
zipfile
ZIP output can now be written to unseekable streams. (Contributed by Serhiy Storchaka in bpo-23252.)
The mode argument of ZipFile.open() method now accepts "x"
to request exclusive creation. (Contributed by Serhiy Storchaka in bpo-21717.)
其他模块级更改
Many functions in the mmap, ossaudiodev, socket, ssl, and codecs modules now accept writable bytes-like objects. (Contributed by Serhiy Storchaka in bpo-23001.)
性能优化
The os.walk() function has been sped up by 3 to 5 times on POSIX systems, and by 7 to 20 times on Windows. This was done using the new os.scandir() function, which exposes file information from the underlying readdir
or FindFirstFile
/FindNextFile
system calls. (Contributed by Ben Hoyt with help from Victor Stinner in bpo-23605.)
Construction of bytes(int)
(filled by zero bytes) is faster and uses less memory for large objects. calloc()
is used instead of malloc()
to allocate memory for these objects. (Contributed by Victor Stinner in bpo-21233.)
Some operations on ipaddress IPv4Network and IPv6Network have been massively sped up, such as subnets(), supernet(), summarize_address_range(), collapse_addresses(). The speed up can range from 3 to 15 times. (Contributed by Antoine Pitrou, Michel Albert, and Markus in bpo-21486, bpo-21487, bpo-20826, bpo-23266.)
Pickling of ipaddress objects was optimized to produce significantly smaller output. (Contributed by Serhiy Storchaka in bpo-23133.)
Many operations on io.BytesIO are now 50% to 100% faster. (Contributed by Serhiy Storchaka in bpo-15381 and David Wilson in bpo-22003.)
The marshal.dumps() function is now faster: 65—85% with versions 3 and 4, 20—25% with versions 0 to 2 on typical data, and up to 5 times in best cases. (Contributed by Serhiy Storchaka in bpo-20416 and bpo-23344.)
The UTF-32 encoder is now 3 to 7 times faster. (Contributed by Serhiy Storchaka in bpo-15027.)
Regular expressions are now parsed up to 10% faster. (Contributed by Serhiy Storchaka in bpo-19380.)
The json.dumps() function was optimized to run with ensure_ascii=False
as fast as with ensure_ascii=True
. (Contributed by Naoki Inada in bpo-23206.)
The PyObject_IsInstance() and PyObject_IsSubclass() functions have been sped up in the common case that the second argument has type as its metaclass. (Contributed Georg Brandl by in bpo-22540.)
Method caching was slightly improved, yielding up to 5% performance improvement in some benchmarks. (Contributed by Antoine Pitrou in bpo-22847.)
Objects from the random module now use 50% less memory on 64-bit builds. (Contributed by Serhiy Storchaka in bpo-23488.)
The property() getter calls are up to 25% faster. (Contributed by Joe Jevnik in bpo-23910.)
Instantiation of fractions.Fraction is now up to 30% faster. (Contributed by Stefan Behnel in bpo-22464.)
String methods find(), rfind(), split(), partition() and the in string operator are now significantly faster for searching 1-character substrings. (Contributed by Serhiy Storchaka in bpo-23573.)
构建和 C API 的改变
增加了 calloc
函数
(Victor Stinner 贡献于 bpo-21233.)
新的 encoding/decoding 帮助函数:
Py_DecodeLocale() (替代
_Py_char2wchar()
),Py_EncodeLocale() (替代
_Py_wchar2char()
).
(由 Victor Stinner 在 bpo-18395 中贡献。)
A new PyCodec_NameReplaceErrors() function to replace the unicode encode error with \N{...}
escapes. (Contributed by Serhiy Storchaka in bpo-19676.)
A new PyErr_FormatV() function similar to PyErr_Format(), but accepts a va_list
argument. (Contributed by Antoine Pitrou in bpo-18711.)
A new PyExc_RecursionError
exception. (Contributed by Georg Brandl in bpo-19235.)
New PyModule_FromDefAndSpec(), PyModule_FromDefAndSpec2(), and PyModule_ExecDef() functions introduced by PEP 489 — multi-phase extension module initialization. (Contributed by Petr Viktorin in bpo-24268.)
New PyNumber_MatrixMultiply() and PyNumber_InPlaceMatrixMultiply() functions to perform matrix multiplication. (Contributed by Benjamin Peterson in bpo-21176. See also PEP 465 for details.)
The PyTypeObject.tp_finalize slot is now part of the stable ABI.
Windows builds now require Microsoft Visual C++ 14.0, which is available as part of Visual Studio 2015.
Extension modules now include a platform information tag in their filename on some platforms (the tag is optional, and CPython will import extensions without it, although if the tag is present and mismatched, the extension won’t be loaded):
On Linux, extension module filenames end with
.cpython-<major><minor>m-<architecture>-<os>.pyd
:<major>
is the major number of the Python version; for Python 3.5 this is3
.<minor>
is the minor number of the Python version; for Python 3.5 this is5
.<architecture>
is the hardware architecture the extension module was built to run on. It’s most commonly eitheri386
for 32-bit Intel platforms orx86_64
for 64-bit Intel (and AMD) platforms.<os>
is alwayslinux-gnu
, except for extensions built to talk to the 32-bit ABI on 64-bit platforms, in which case it islinux-gnu32
(and<architecture>
will bex86_64
).
On Windows, extension module filenames end with
<debug>.cp<major><minor>-<platform>.pyd
:<major>
is the major number of the Python version; for Python 3.5 this is3
.<minor>
is the minor number of the Python version; for Python 3.5 this is5
.<platform>
is the platform the extension module was built for, eitherwin32
for Win32,win_amd64
for Win64,win_ia64
for Windows Itanium 64, andwin_arm
for Windows on ARM.If built in debug mode,
<debug>
will be_d
, otherwise it will be blank.
On OS X platforms, extension module filenames now end with
-darwin.so
.On all other platforms, extension module filenames are the same as they were with Python 3.4.
弃用
新关键字
async
and await
are not recommended to be used as variable, class, function or module names. Introduced by PEP 492 in Python 3.5, they will become proper keywords in Python 3.7.
已弃用的 Python 行为
Raising the StopIteration exception inside a generator will now generate a silent PendingDeprecationWarning, which will become a non-silent deprecation warning in Python 3.6 and will trigger a RuntimeError in Python 3.7. See PEP 479: Change StopIteration handling inside generators for details.
不支持的操作系统
Windows XP is no longer supported by Microsoft, thus, per PEP 11, CPython 3.5 is no longer officially supported on this OS.
已弃用的 Python 模块、函数和方法
The formatter
module has now graduated to full deprecation and is still slated for removal in Python 3.6.
The asyncio.async()
function is deprecated in favor of ensure_future().
The smtpd module has in the past always decoded the DATA portion of email messages using the utf-8
codec. This can now be controlled by the new decode_data keyword to SMTPServer. The default value is True
, but this default is deprecated. Specify the decode_data keyword with an appropriate value to avoid the deprecation warning.
Directly assigning values to the key, value and coded_value of http.cookies.Morsel objects is deprecated. Use the set() method instead. In addition, the undocumented LegalChars parameter of set() is deprecated, and is now ignored.
Passing a format string as keyword argument format_string to the format() method of the string.Formatter class has been deprecated. (Contributed by Serhiy Storchaka in bpo-23671.)
The platform.dist()
and platform.linux_distribution()
functions are now deprecated. Linux distributions use too many different ways of describing themselves, so the functionality is left to a package. (Contributed by Vajrasky Kok and Berker Peksag in bpo-1322.)
The previously undocumented from_function
and from_builtin
methods of inspect.Signature are deprecated. Use the new Signature.from_callable() method instead. (Contributed by Yury Selivanov in bpo-24248.)
The inspect.getargspec()
function is deprecated and scheduled to be removed in Python 3.6. (See bpo-20438 for details.)
The inspect getfullargspec(), getcallargs(), and formatargspec()
functions are deprecated in favor of the inspect.signature() API. (Contributed by Yury Selivanov in bpo-20438.)
getargvalues() and formatargvalues() functions were inadvertently marked as deprecated with the release of Python 3.5.0.
Use of re.LOCALE flag with str patterns or re.ASCII is now deprecated. (Contributed by Serhiy Storchaka in bpo-22407.)
Use of unrecognized special sequences consisting of '\'
and an ASCII letter in regular expression patterns and replacement patterns now raises a deprecation warning and will be forbidden in Python 3.6. (Contributed by Serhiy Storchaka in bpo-23622.)
The undocumented and unofficial use_load_tests default argument of the unittest.TestLoader.loadTestsFromModule() method now is deprecated and ignored. (Contributed by Robert Collins and Barry A. Warsaw in bpo-16662.)
移除
API 与特性的移除
The following obsolete and previously deprecated APIs and features have been removed:
The
__version__
attribute has been dropped from the email package. The email code hasn’t been shipped separately from the stdlib for a long time, and the__version__
string was not updated in the last few releases.The internal
Netrc
class in the ftplib module was deprecated in 3.4, and has now been removed. (Contributed by Matt Chaput in bpo-6623.)The concept of
.pyo
files has been removed.The JoinableQueue class in the provisional asyncio module was deprecated in 3.4.4 and is now removed. (Contributed by A. Jesse Jiryu Davis in bpo-23464.)
移植到Python 3.5
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.
Python 行为的改变
由于一个疏忽,之前的 Python 版本会错误地接受以下语法:
f(1 for x in [1], *args)
f(1 for x in [1], **kwargs)
Python 3.5 now correctly raises a SyntaxError, as generator expressions must be put in parentheses if not a sole argument to a function.
Python API 的变化
PEP 475: System calls are now retried when interrupted by a signal instead of raising InterruptedError if the Python signal handler does not raise an exception.
Before Python 3.5, a datetime.time object was considered to be false if it represented midnight in UTC. This behavior was considered obscure and error-prone and has been removed in Python 3.5. See bpo-13936 for full details.
The
ssl.SSLSocket.send()
method now raises either ssl.SSLWantReadError or ssl.SSLWantWriteError on a non-blocking socket if the operation would block. Previously, it would return0
. (Contributed by Nikolaus Rath in bpo-20951.)The
__name__
attribute of generators is now set from the function name, instead of being set from the code name. Usegen.gi_code.co_name
to retrieve the code name. Generators also have a new__qualname__
attribute, the qualified name, which is now used for the representation of a generator (repr(gen)
). (Contributed by Victor Stinner in bpo-21205.)The deprecated “strict” mode and argument of HTMLParser,
HTMLParser.error()
, and theHTMLParserError
exception have been removed. (Contributed by Ezio Melotti in bpo-15114.) The convert_charrefs argument of HTMLParser is nowTrue
by default. (Contributed by Berker Peksag in bpo-21047.)Although it is not formally part of the API, it is worth noting for porting purposes (ie: fixing tests) that error messages that were previously of the form “‘sometype’ does not support the buffer protocol” are now of the form “a bytes-like object is required, not ‘sometype’”. (Contributed by Ezio Melotti in bpo-16518.)
If the current directory is set to a directory that no longer exists then FileNotFoundError will no longer be raised and instead find_spec() will return
None
without cachingNone
in sys.path_importer_cache, which is different than the typical case (bpo-22834).HTTP status code and messages from http.client and http.server were refactored into a common HTTPStatus enum. The values in http.client and http.server remain available for backwards compatibility. (Contributed by Demian Brecht in bpo-21793.)
When an import loader defines
importlib.machinery.Loader.exec_module()
it is now expected to also definecreate_module()
(raises a DeprecationWarning now, will be an error in Python 3.6). If the loader inherits from importlib.abc.Loader then there is nothing to do, else simply definecreate_module()
to returnNone
. (Contributed by Brett Cannon in bpo-23014.)The re.split() function always ignored empty pattern matches, so the
"x*"
pattern worked the same as"x+"
, and the"\b"
pattern never worked. Now re.split() raises a warning if the pattern could match an empty string. For compatibility, use patterns that never match an empty string (e.g."x+"
instead of"x*"
). Patterns that could only match an empty string (such as"\b"
) now raise an error. (Contributed by Serhiy Storchaka in bpo-22818.)The http.cookies.Morsel dict-like interface has been made self consistent: morsel comparison now takes the key and value into account, copy() now results in a Morsel instance rather than a dict, and update() will now raise an exception if any of the keys in the update dictionary are invalid. In addition, the undocumented LegalChars parameter of set() is deprecated and is now ignored. (Contributed by Demian Brecht in bpo-2211.)
PEP 488 has removed
.pyo
files from Python and introduced the optionalopt-
tag in.pyc
file names. The importlib.util.cache_from_source() has gained an optimization parameter to help control theopt-
tag. Because of this, the debug_override parameter of the function is now deprecated..pyo
files are also no longer supported as a file argument to the Python interpreter and thus serve no purpose when distributed on their own (i.e. sourceless code distribution). Due to the fact that the magic number for bytecode has changed in Python 3.5, all old.pyo
files from previous versions of Python are invalid regardless of this PEP.The socket module now exports the CAN_RAW_FD_FRAMES constant on linux 3.6 and greater.
The ssl.cert_time_to_seconds() function now interprets the input time as UTC and not as local time, per RFC 5280. Additionally, the return value is always an int. (Contributed by Akira Li in bpo-19940.)
The
pygettext.py
Tool now uses the standard +NNNN format for timezones in the POT-Creation-Date header.The smtplib module now uses sys.stderr instead of the previous module-level
stderr
variable for debug output. If your (test) program depends on patching the module-level variable to capture the debug output, you will need to update it to capture sys.stderr instead.The str.startswith() and str.endswith() methods no longer return
True
when finding the empty string and the indexes are completely out of range. (Contributed by Serhiy Storchaka in bpo-24284.)The inspect.getdoc() function now returns documentation strings inherited from base classes. Documentation strings no longer need to be duplicated if the inherited documentation is appropriate. To suppress an inherited string, an empty string must be specified (or the documentation may be filled in). This change affects the output of the pydoc module and the help() function. (Contributed by Serhiy Storchaka in bpo-15582.)
Nested functools.partial() calls are now flattened. If you were relying on the previous behavior, you can now either add an attribute to a functools.partial() object or you can create a subclass of functools.partial(). (Contributed by Alexander Belopolsky in bpo-7830.)
C API 的变化
The undocumented
format
member of the (non-public)PyMemoryViewObject
structure has been removed. All extensions relying on the relevant parts inmemoryobject.h
must be rebuilt.The
PyMemAllocator
structure was renamed to PyMemAllocatorEx and a newcalloc
field was added.Removed non-documented macro
PyObject_REPR
which leaked references. Use format character%R
in PyUnicode_FromFormat()-like functions to format the repr() of the object. (Contributed by Serhiy Storchaka in bpo-22453.)Because the lack of the
__module__
attribute breaks pickling and introspection, a deprecation warning is now raised for builtin types without the__module__
attribute. This would be an AttributeError in the future. (Contributed by Serhiy Storchaka in bpo-20204.)As part of the PEP 492 implementation, the
tp_reserved
slot of PyTypeObject was replaced with atp_as_async
slot. Refer to 协程对象 for new types, structures and functions.
Python 3.5.4 的显著变化
New make regen-all
build target
To simplify cross-compilation, and to ensure that CPython can reliably be compiled without requiring an existing version of Python to already be available, the autotools-based build system no longer attempts to implicitly recompile generated files based on file modification times.
Instead, a new make regen-all
command has been added to force regeneration of these files when desired (e.g. after an initial version of Python has already been built based on the pregenerated versions).
More selective regeneration targets are also defined - see Makefile.pre.in for details.
(由 Victor Stinner 在 bpo-23404 中贡献。)
3.5.4 新版功能.
Removal of make touch
build target
The make touch
build target previously used to request implicit regeneration of generated files by updating their modification times has been removed.
It has been replaced by the new make regen-all
target.
(由 Victor Stinner 在 bpo-23404 中贡献。)
在 3.5.4 版更改.