Nouveautés de Python 3.5¶
Release: | 3.5.0a3 |
---|---|
Date: | mai 23, 2017 |
This article explains the new features in Python 3.5, compared to 3.4.
For full details, see the Misc/NEWS file.
Note
Prerelease users should be aware that this document is currently in draft form. It will be updated substantially as Python 3.5 moves towards release, so it’s worth checking back even after reading earlier versions.
Voir aussi
PEP 478 - Python 3.5 Release Schedule
Summary – Release highlights¶
New syntax features:
- PEP 465, a new matrix multiplication operator:
a @ b
.
New library modules:
New built-in features:
bytes % args
,bytearray % args
: PEP 461 - Adding%
formatting to bytes and bytearray
Implementation improvements:
- When the
LC_TYPE
locale is the POSIX locale (C
locale),sys.stdin
andsys.stdout
are now using thesurrogateescape
error handler, instead of thestrict
error handler (issue 19977).
Significantly Improved Library Modules:
- None yet.
Security improvements:
- None yet.
Please read on for a comprehensive list of user-facing changes.
PEP 461 - Adding % formatting to bytes and bytearray¶
This PEP proposes adding % formatting operations similar to Python 2’s str
type to bytes
and bytearray
.
Exemples :
>>> b'Hello %s!' % b'World'
b'Hello World!'
>>> b'x=%i y=%f' % (1, 2.5)
b'x=1 y=2.500000'
Unicode is not allowed for %s
, but it is accepted by %a
(equivalent of
repr(obj).encode('ascii', 'backslashreplace')
):
>>> b'Hello %s!' % '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'"
Voir aussi
PEP 461 – Adding % formatting to bytes and bytearray
PEP 465 - A dedicated infix operator for matrix multiplication¶
This PEP proposes a new binary operator to be used for matrix multiplication,
called @
. (Mnemonic: @
is *
for mATrices.)
Voir aussi
PEP 465 – A dedicated infix operator for matrix multiplication
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 os.scandir()
, which speeds it up by 3-5 times
on POSIX systems and by 7-20 times on Windows systems.
PEP and implementation written by Ben Hoyt with the help of Victor Stinner.
Voir aussi
PEP 471 – os.scandir() function – a better and faster directory iterator
PEP 475: Retry system calls failing with EINTR¶
PEP 475 adds support for automatic retry of system calls failing with EINTR: this means that user code doesn’t have to deal with EINTR or InterruptedError manually, and should make it more robust against asynchronous signal reception.
Voir aussi
PEP 475 – Retry system calls failing with EINTR
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.
Voir aussi
PEP 486 – Make the Python Launcher aware of virtual environments
Other Language Changes¶
Some smaller changes made to the core Python language are:
- Added the
'namereplace'
error handlers. The'backslashreplace'
error handlers now works with decoding and translating. (Contributed by Serhiy Storchaka in issue 19676 and issue 22286.) - The
-b
option now affects comparisons ofbytes
withint
. (Contributed by Serhiy Storchaka in issue 23681)
New Modules¶
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 issue 1739468 but which were not well
publicised, 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
Improved Modules¶
argparse¶
ArgumentParser
now allows to disable abbreviated usage of long options by setting allow_abbrev toFalse
. (Contributed by Jonathan Paugh, Steven Bethard, paul j3 and Daniel Eriksson.)
cgi¶
FieldStorage
now supports the context management protocol. (Contributed by Berker Peksag in issue 20289.)
code¶
- The
code.InteractiveInterpreter.showtraceback()
method now prints the full chained traceback, just like the interactive interpreter. (Contributed by Claudiu Popa in issue 17442.)
compileall¶
compileall.compile_dir()
andcompileall
’s command-line interface can now do parallel bytecode compilation. (Contributed by Claudiu Popa in issue 16104.)
contextlib¶
- The new
contextlib.redirect_stderr()
context manager(similar tocontextlib.redirect_stdout()
) makes it easier for utility scripts to handle inflexible APIs that write their output tosys.stderr
and don’t provide any options to redirect it. (Contributed by Berker Peksag in issue 22389.)
difflib¶
- The charset of the HTML document generated by
difflib.HtmlDiff.make_file()
can now be customized by using charset keyword-only parameter. The default charset of HTML document changed from'ISO-8859-1'
to'utf-8'
. (Contributed by Berker Peksag in issue 2052.)
distutils¶
- The
build
andbuild_ext
commands now accept a-j
option to enable parallel building of extension modules. (Contributed by Antoine Pitrou in issue 5309.)
doctest¶
doctest.DocTestSuite()
returns an emptyunittest.TestSuite
if module contains no docstrings instead of raisingValueError
. (Contributed by Glenn Jones in issue 15916.)
glob¶
iglob()
andglob()
now support recursive search in subdirectories using the «**
» pattern. (Contributed by Serhiy Storchaka in issue 13968.)
imaplib¶
IMAP4
now supports the context management protocol. When used in awith
statement, the IMAP4LOGOUT
command will be called automatically at the end of the block. (Contributed by Tarek Ziadé and Serhiy Storchaka in issue 4972.)
imghdr¶
what()
now recognizes the OpenEXR format. (Contributed by Martin Vignali and Claudiu Popa in issue 20295.)
importlib¶
importlib.util.LazyLoader
allows for the lazy loading of modules in applications where startup time is paramount. (Contributed by Brett Cannon in issue 17621.)importlib.abc.InspectLoader.source_to_code()
is now a static method to make it easier to work with source code in a string. With a module object that you want to initialize you can then useexec(code, module.__dict__)
to execute the code in the module.importlib.util.module_from_spec()
is now the preferred way to create a new module. Compared totypes.ModuleType
, this new function will set the various import-controlled attributes based on the passed-in spec object.
inspect¶
inspect.Signature
andinspect.Parameter
are now picklable and hashable. (Contributed by Yury Selivanov in issue 20726 and issue 20334.)- New class method
inspect.Signature.from_callable()
, which makes subclassing ofSignature
easier. (Contributed by Yury Selivanov and Eric Snow in issue 17373.)
ipaddress¶
ipaddress.IPv4Network
andipaddress.IPv6Network
now accept an(address, netmask)
tuple argument, so as to easily construct network objects from existing addresses. (Contributed by Peter Moody and Antoine Pitrou in issue 16531.)
json¶
- The output of
json.tool
command line interface is now in the same order as the input. Use the--sort-keys
option to sort the output of dictionaries alphabetically by key. (Contributed by Berker Peksag in issue 21650.) - JSON decoder now raises
json.JSONDecodeError
instead ofValueError
. (Contributed by Serhiy Storchaka in issue 19361.)
os¶
- New
os.scandir()
function that exposes file information from the operating system when listing a directory.os.scandir()
returns an iterator ofos.DirEntry
objects corresponding to the entries in the directory given by path. (Contributed by Ben Hoyt with the help of Victor Stinner in issue 22524.) os.stat_result
now has ast_file_attributes
attribute on Windows. (Contributed by Ben Hoyt in issue 21719.)
re¶
- Number of capturing groups in regular expression is no longer limited by 100. (Contributed by Serhiy Storchaka in issue 22437.)
- Now unmatched groups are replaced with empty strings in
re.sub()
andre.subn()
. (Contributed by Serhiy Storchaka in issue 1519638.)
math¶
math.inf
andmath.nan
constants added. (Contributed by Mark Dickinson in issue 23185.)
shutil¶
move()
now accepts a copy_function argument, allowing, for example,copy()
to be used instead of the defaultcopy2()
if there is a need to ignore metadata. (Contributed by Claudiu Popa in issue 19840.)
signal¶
- Different constants of
signal
module are now enumeration values using theenum
module. This allows meaningful names to be printed during debugging, instead of integer “magic numbers”. (Contributed by Giampaolo Rodola” in issue 21076.)
smtpd¶
- Both
SMTPServer
andsmtpd.SMTPChannel
now accept a decode_data keyword to determine if the DATA portion of the SMTP transaction is decoded using theutf-8
codec or is instead provided toprocess_message()
as a byte string. The default isTrue
for backward compatibility reasons, but will change toFalse
in Python 3.6. (Contributed by Maciej Szulik in issue 19662.) - 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 issue 14758.) SMTPServer
now supports RFC 6531 via the enable_SMTPUTF8 constructor argument and a user-providedprocess_smtputf8_message()
method.
smtplib¶
- A new
auth()
method provides a convenient way to implement custom authentication mechanisms. (Contributed by Milan Oberkirch in issue 15014.)
sndhdr¶
what()
andwhathdr()
now returnnamedtuple()
. (Contributed by Claudiu Popa in issue 18615.)
socket¶
- New
socket.socket.sendfile()
method allows to send a file over a socket by using high-performanceos.sendfile()
function on UNIX resulting in uploads being from 2x to 3x faster than when using plainsocket.socket.send()
. (Contributed by Giampaolo Rodola” in issue 17552.)
sysconfig¶
- The user scripts directory on Windows is now versioned. (Contributed by Paul Moore in issue 23437.)
tarfile¶
- The
tarfile.open()
function now supports'x'
(exclusive creation) mode. (Contributed by Berker Peksag in issue 21717.)
time¶
- The
time.monotonic()
function is now always available. (Contributed by Victor Stinner in issue 22043.)
urllib¶
- A new
urllib.request.HTTPBasicPriorAuthHandler
allows HTTP Basic Authentication credentials to be sent unconditionally with the first HTTP request, rather than waiting for a HTTP 401 Unauthorized response from the server. (Contributed by Matej Cepl in issue 19494.)
wsgiref¶
- headers parameter of
wsgiref.headers.Headers
is now optional. (Contributed by Pablo Torres Navarrete and SilentGhost in issue 5800.)
xmlrpc¶
xmlrpc.client.ServerProxy
is now a context manager. (Contributed by Claudiu Popa in issue 20627.)
faulthandler¶
enable()
,register()
,dump_traceback()
anddump_traceback_later()
functions now accept file descriptors. (Contributed by Wei Wu in issue 23566.)
zipfile¶
- Added support for writing ZIP files to unseekable streams. (Contributed by Serhiy Storchaka in issue 23252.)
- The
zipfile.ZipFile.open()
function now supports'x'
(exclusive creation) mode. (Contributed by Serhiy Storchaka in issue 21717.)
Optimizations¶
The following performance enhancements have been added:
os.walk()
has been sped up by 3-5x on POSIX systems and 7-20x on Windows. This was done using the newos.scandir()
function, which exposes file information from the underlyingreaddir
andFindFirstFile
/FindNextFile
system calls. (Contributed by Ben Hoyt with help from Victor Stinner in issue 23605.)- Construction of
bytes(int)
(filled by zero bytes) is faster and use less memory for large objects.calloc()
is used instead ofmalloc()
to allocate memory for these objects. - Some operations on
IPv4Network
andIPv6Network
have been massively sped up, such assubnets()
,supernet()
,summarize_address_range()
,collapse_addresses()
. The speed up can range from 3x to 15x. (issue 21486, issue 21487, issue 20826) - Many operations on
io.BytesIO
are now 50% to 100% faster. (Contributed by Serhiy Storchaka in issue 15381 and David Wilson in issue 22003.) marshal.dumps()
is now faster (65%-85% with versions 3–4, 20-25% with versions 0–2 on typical data, and up to 5x in best cases). (Contributed by Serhiy Storchaka in issue 20416 and issue 23344.)
Build and C API Changes¶
Changes to Python’s build process and to the C API include:
- New
calloc
functions:PyMem_RawCalloc()
PyMem_Calloc()
PyObject_Calloc()
_PyObject_GC_Calloc()
Deprecated¶
Unsupported Operating Systems¶
- None yet.
Deprecated Python modules, functions and methods¶
- The
formatter
module has now graduated to full deprecation and is still slated for removal in Python 3.6. smtpd
has in the past always decoded the DATA portion of email messages using theutf-8
codec. This can now be controlled by the new decode_data keyword toSMTPServer
. The default value isTrue
, 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
andcoded_value
ofMorsel
objects is deprecated. Use theset()
method instead. In addition, the undocumented LegalChars parameter ofset()
is deprecated, and is now ignored. - Passing a format string as keyword argument format_string to the
format()
method of thestring.Formatter
class has been deprecated.
Deprecated functions and types of the C API¶
- None yet.
Deprecated features¶
- None yet.
Removed¶
API and Feature Removals¶
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 theftplib
module was deprecated in 3.4, and has now been removed. (Contributed by Matt Chaput in issue 6623.)
Portage vers Python 3.5¶
This section lists previously described changes and other bugfixes that may require changes to your code.
Changes in the Python API¶
- PEP 475: the following functions are now retried when interrupted instead
of raising
InterruptedError
if the 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 issue 13936 for full details. ssl.SSLSocket.send()
now raises eitherssl.SSLWantReadError
orssl.SSLWantWriteError
on a non-blocking socket if the operation would block. Previously, it would return 0. See issue 20951.- The
__name__
attribute of generator 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)
). See issue 21205. - The deprecated « strict » mode and argument of
HTMLParser
,HTMLParser.error()
, and theHTMLParserError
exception have been removed. (Contributed by Ezio Melotti in issue 15114.) The convert_charrefs argument ofHTMLParser
is nowTrue
by default. (Contributed by Berker Peksag in issue 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 issue 16518.)
- If the current directory is set to a directory that no longer exists then
FileNotFoundError
will no longer be raised and insteadfind_spec()
will returnNone
without cachingNone
insys.path_importer_cache
which is different than the typical case (issue 22834). - HTTP status code and messages from
http.client
andhttp.server
were refactored into a commonHTTPStatus
enum. The values inhttp.client
andhttp.server
remain available for backwards compatibility. (Contributed by Demian Brecht in issue 21793.) - When an import loader defines
exec_module()
it is now expected to also definecreate_module()
(raises aDeprecationWarning
now, will be an error in Python 3.6). If the loader inherits fromimportlib.abc.Loader
then there is nothing to do, else simply definecreate_module()
to returnNone
(issue 23014). re.split()
always ignored empty pattern matches, so the'x*'
pattern worked the same as'x+'
, and the'\b'
pattern never worked. Nowre.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.- The
Morsel
dict-like interface has been made self consistent: morsel comparison now takes thekey
andvalue
into account,copy()
now results in aMorsel
instance rather than adict
, andupdate()
will now raise an exception if any of the keys in the update dictionary are invalid. In addition, the undocumented LegalChars parameter ofset()
is deprecated and is now ignored. (issue 2211)
Changes in the C API¶
The undocumented
format
member of the (non-public)PyMemoryViewObject
structure has been removed.All extensions relying on the relevant parts in
memoryobject.h
must be rebuilt.The
PyMemAllocator
structure was renamed toPyMemAllocatorEx
and a newcalloc
field was added.Removed non-documented macro
PyObject_REPR
which leaked references. Use format character%R
inPyUnicode_FromFormat()
-like functions to format therepr()
of the object.Because the lack of the
__module__
attribute breaks pickling and introspection, a deprecation warning now is raised for builtin type without the__module__
attribute. Would be an AttributeError in future. (issue 20204)