2518 lines
97 KiB
ReStructuredText
2518 lines
97 KiB
ReStructuredText
****************************
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What's New In Python 3.3
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****************************
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.. Rules for maintenance:
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* Anyone can add text to this document. Do not spend very much time
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on the wording of your changes, because your text will probably
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get rewritten to some degree.
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* The maintainer will go through Misc/NEWS periodically and add
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changes; it's therefore more important to add your changes to
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Misc/NEWS than to this file.
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* This is not a complete list of every single change; completeness
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is the purpose of Misc/NEWS. Some changes I consider too small
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or esoteric to include. If such a change is added to the text,
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I'll just remove it. (This is another reason you shouldn't spend
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too much time on writing your addition.)
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* If you want to draw your new text to the attention of the
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maintainer, add 'XXX' to the beginning of the paragraph or
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section.
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* It's OK to just add a fragmentary note about a change. For
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example: "XXX Describe the transmogrify() function added to the
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socket module." The maintainer will research the change and
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write the necessary text.
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* You can comment out your additions if you like, but it's not
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necessary (especially when a final release is some months away).
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* Credit the author of a patch or bugfix. Just the name is
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sufficient; the e-mail address isn't necessary.
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* It's helpful to add the bug/patch number as a comment:
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XXX Describe the transmogrify() function added to the socket
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module.
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(Contributed by P.Y. Developer in :issue:`12345`.)
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This saves the maintainer the effort of going through the Mercurial log
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when researching a change.
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This article explains the new features in Python 3.3, compared to 3.2.
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Python 3.3 was released on September 29, 2012. For full details,
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see the `changelog <https://docs.python.org/3.3/whatsnew/changelog.html>`_.
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.. seealso::
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:pep:`398` - Python 3.3 Release Schedule
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Summary -- Release highlights
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=============================
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.. This section singles out the most important changes in Python 3.3.
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Brevity is key.
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New syntax features:
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* New ``yield from`` expression for :ref:`generator delegation <pep-380>`.
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* The ``u'unicode'`` syntax is accepted again for :class:`str` objects.
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New library modules:
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* :mod:`faulthandler` (helps debugging low-level crashes)
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* :mod:`ipaddress` (high-level objects representing IP addresses and masks)
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* :mod:`lzma` (compress data using the XZ / LZMA algorithm)
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* :mod:`unittest.mock` (replace parts of your system under test with mock objects)
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* :mod:`venv` (Python :ref:`virtual environments <pep-405>`, as in the
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popular ``virtualenv`` package)
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New built-in features:
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* Reworked :ref:`I/O exception hierarchy <pep-3151>`.
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Implementation improvements:
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* Rewritten :ref:`import machinery <importlib>` based on :mod:`importlib`.
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* More compact :ref:`unicode strings <pep-393>`.
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* More compact :ref:`attribute dictionaries <pep-412>`.
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Significantly Improved Library Modules:
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* C Accelerator for the :ref:`decimal <new-decimal>` module.
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* Better unicode handling in the :ref:`email <new-email>` module
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(:term:`provisional <provisional package>`).
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Security improvements:
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* Hash randomization is switched on by default.
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Please read on for a comprehensive list of user-facing changes.
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.. _pep-405:
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PEP 405: Virtual Environments
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=============================
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Virtual environments help create separate Python setups while sharing a
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system-wide base install, for ease of maintenance. Virtual environments
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have their own set of private site packages (i.e. locally-installed
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libraries), and are optionally segregated from the system-wide site
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packages. Their concept and implementation are inspired by the popular
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``virtualenv`` third-party package, but benefit from tighter integration
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with the interpreter core.
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This PEP adds the :mod:`venv` module for programmatic access, and the
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``pyvenv`` script for command-line access and
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administration. The Python interpreter checks for a ``pyvenv.cfg``,
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file whose existence signals the base of a virtual environment's directory
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tree.
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.. seealso::
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:pep:`405` - Python Virtual Environments
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PEP written by Carl Meyer; implementation by Carl Meyer and Vinay Sajip
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PEP 420: Implicit Namespace Packages
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====================================
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Native support for package directories that don't require ``__init__.py``
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marker files and can automatically span multiple path segments (inspired by
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various third party approaches to namespace packages, as described in
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:pep:`420`)
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.. seealso::
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:pep:`420` - Implicit Namespace Packages
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PEP written by Eric V. Smith; implementation by Eric V. Smith
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and Barry Warsaw
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.. _pep-3118-update:
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PEP 3118: New memoryview implementation and buffer protocol documentation
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=========================================================================
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The implementation of :pep:`3118` has been significantly improved.
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The new memoryview implementation comprehensively fixes all ownership and
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lifetime issues of dynamically allocated fields in the Py_buffer struct
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that led to multiple crash reports. Additionally, several functions that
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crashed or returned incorrect results for non-contiguous or multi-dimensional
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input have been fixed.
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The memoryview object now has a PEP-3118 compliant getbufferproc()
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that checks the consumer's request type. Many new features have been
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added, most of them work in full generality for non-contiguous arrays
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and arrays with suboffsets.
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The documentation has been updated, clearly spelling out responsibilities
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for both exporters and consumers. Buffer request flags are grouped into
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basic and compound flags. The memory layout of non-contiguous and
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multi-dimensional NumPy-style arrays is explained.
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Features
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--------
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* All native single character format specifiers in struct module syntax
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(optionally prefixed with '@') are now supported.
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* With some restrictions, the cast() method allows changing of format and
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shape of C-contiguous arrays.
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* Multi-dimensional list representations are supported for any array type.
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* Multi-dimensional comparisons are supported for any array type.
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* One-dimensional memoryviews of hashable (read-only) types with formats B,
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b or c are now hashable. (Contributed by Antoine Pitrou in :issue:`13411`.)
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* Arbitrary slicing of any 1-D arrays type is supported. For example, it
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is now possible to reverse a memoryview in O(1) by using a negative step.
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API changes
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-----------
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* The maximum number of dimensions is officially limited to 64.
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* The representation of empty shape, strides and suboffsets is now
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an empty tuple instead of ``None``.
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* Accessing a memoryview element with format 'B' (unsigned bytes)
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now returns an integer (in accordance with the struct module syntax).
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For returning a bytes object the view must be cast to 'c' first.
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* memoryview comparisons now use the logical structure of the operands
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and compare all array elements by value. All format strings in struct
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module syntax are supported. Views with unrecognised format strings
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are still permitted, but will always compare as unequal, regardless
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of view contents.
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* For further changes see `Build and C API Changes`_ and `Porting C code`_.
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(Contributed by Stefan Krah in :issue:`10181`.)
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.. seealso::
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:pep:`3118` - Revising the Buffer Protocol
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.. _pep-393:
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PEP 393: Flexible String Representation
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=======================================
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The Unicode string type is changed to support multiple internal
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representations, depending on the character with the largest Unicode ordinal
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(1, 2, or 4 bytes) in the represented string. This allows a space-efficient
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representation in common cases, but gives access to full UCS-4 on all
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systems. For compatibility with existing APIs, several representations may
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exist in parallel; over time, this compatibility should be phased out.
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On the Python side, there should be no downside to this change.
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On the C API side, :pep:`393` is fully backward compatible. The legacy API
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should remain available at least five years. Applications using the legacy
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API will not fully benefit of the memory reduction, or - worse - may use
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a bit more memory, because Python may have to maintain two versions of each
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string (in the legacy format and in the new efficient storage).
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Functionality
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-------------
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Changes introduced by :pep:`393` are the following:
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* Python now always supports the full range of Unicode code points, including
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non-BMP ones (i.e. from ``U+0000`` to ``U+10FFFF``). The distinction between
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narrow and wide builds no longer exists and Python now behaves like a wide
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build, even under Windows.
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* With the death of narrow builds, the problems specific to narrow builds have
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also been fixed, for example:
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* :func:`len` now always returns 1 for non-BMP characters,
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so ``len('\U0010FFFF') == 1``;
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* surrogate pairs are not recombined in string literals,
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so ``'\uDBFF\uDFFF' != '\U0010FFFF'``;
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* indexing or slicing non-BMP characters returns the expected value,
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so ``'\U0010FFFF'[0]`` now returns ``'\U0010FFFF'`` and not ``'\uDBFF'``;
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* all other functions in the standard library now correctly handle
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non-BMP code points.
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* The value of :data:`sys.maxunicode` is now always ``1114111`` (``0x10FFFF``
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in hexadecimal). The :c:func:`PyUnicode_GetMax` function still returns
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either ``0xFFFF`` or ``0x10FFFF`` for backward compatibility, and it should
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not be used with the new Unicode API (see :issue:`13054`).
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* The :file:`./configure` flag ``--with-wide-unicode`` has been removed.
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Performance and resource usage
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------------------------------
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The storage of Unicode strings now depends on the highest code point in the string:
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* pure ASCII and Latin1 strings (``U+0000-U+00FF``) use 1 byte per code point;
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* BMP strings (``U+0000-U+FFFF``) use 2 bytes per code point;
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* non-BMP strings (``U+10000-U+10FFFF``) use 4 bytes per code point.
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The net effect is that for most applications, memory usage of string
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storage should decrease significantly - especially compared to former
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wide unicode builds - as, in many cases, strings will be pure ASCII
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even in international contexts (because many strings store non-human
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language data, such as XML fragments, HTTP headers, JSON-encoded data,
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etc.). We also hope that it will, for the same reasons, increase CPU
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cache efficiency on non-trivial applications. The memory usage of
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Python 3.3 is two to three times smaller than Python 3.2, and a little
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bit better than Python 2.7, on a Django benchmark (see the PEP for
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details).
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.. seealso::
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:pep:`393` - Flexible String Representation
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PEP written by Martin von Löwis; implementation by Torsten Becker
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and Martin von Löwis.
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.. _pep-397:
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PEP 397: Python Launcher for Windows
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====================================
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The Python 3.3 Windows installer now includes a ``py`` launcher application
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that can be used to launch Python applications in a version independent
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fashion.
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This launcher is invoked implicitly when double-clicking ``*.py`` files.
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If only a single Python version is installed on the system, that version
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will be used to run the file. If multiple versions are installed, the most
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recent version is used by default, but this can be overridden by including
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a Unix-style "shebang line" in the Python script.
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The launcher can also be used explicitly from the command line as the ``py``
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application. Running ``py`` follows the same version selection rules as
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implicitly launching scripts, but a more specific version can be selected
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by passing appropriate arguments (such as ``-3`` to request Python 3 when
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Python 2 is also installed, or ``-2.6`` to specifically request an earlier
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Python version when a more recent version is installed).
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In addition to the launcher, the Windows installer now includes an
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option to add the newly installed Python to the system PATH. (Contributed
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by Brian Curtin in :issue:`3561`.)
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.. seealso::
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:pep:`397` - Python Launcher for Windows
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PEP written by Mark Hammond and Martin v. Löwis; implementation by
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Vinay Sajip.
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Launcher documentation: :ref:`launcher`
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Installer PATH modification: :ref:`windows-path-mod`
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.. _pep-3151:
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PEP 3151: Reworking the OS and IO exception hierarchy
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=====================================================
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The hierarchy of exceptions raised by operating system errors is now both
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simplified and finer-grained.
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You don't have to worry anymore about choosing the appropriate exception
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type between :exc:`OSError`, :exc:`IOError`, :exc:`EnvironmentError`,
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:exc:`WindowsError`, :exc:`mmap.error`, :exc:`socket.error` or
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:exc:`select.error`. All these exception types are now only one:
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:exc:`OSError`. The other names are kept as aliases for compatibility
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reasons.
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Also, it is now easier to catch a specific error condition. Instead of
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inspecting the ``errno`` attribute (or ``args[0]``) for a particular
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constant from the :mod:`errno` module, you can catch the adequate
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:exc:`OSError` subclass. The available subclasses are the following:
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* :exc:`BlockingIOError`
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* :exc:`ChildProcessError`
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* :exc:`ConnectionError`
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* :exc:`FileExistsError`
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* :exc:`FileNotFoundError`
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* :exc:`InterruptedError`
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* :exc:`IsADirectoryError`
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* :exc:`NotADirectoryError`
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* :exc:`PermissionError`
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* :exc:`ProcessLookupError`
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* :exc:`TimeoutError`
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And the :exc:`ConnectionError` itself has finer-grained subclasses:
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* :exc:`BrokenPipeError`
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* :exc:`ConnectionAbortedError`
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* :exc:`ConnectionRefusedError`
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* :exc:`ConnectionResetError`
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Thanks to the new exceptions, common usages of the :mod:`errno` can now be
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avoided. For example, the following code written for Python 3.2::
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from errno import ENOENT, EACCES, EPERM
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try:
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with open("document.txt") as f:
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content = f.read()
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except IOError as err:
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if err.errno == ENOENT:
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print("document.txt file is missing")
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elif err.errno in (EACCES, EPERM):
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print("You are not allowed to read document.txt")
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else:
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raise
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can now be written without the :mod:`errno` import and without manual
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inspection of exception attributes::
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try:
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with open("document.txt") as f:
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content = f.read()
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except FileNotFoundError:
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print("document.txt file is missing")
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except PermissionError:
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print("You are not allowed to read document.txt")
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.. seealso::
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:pep:`3151` - Reworking the OS and IO Exception Hierarchy
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PEP written and implemented by Antoine Pitrou
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.. index::
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single: yield; yield from (in What's New)
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.. _pep-380:
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PEP 380: Syntax for Delegating to a Subgenerator
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================================================
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PEP 380 adds the ``yield from`` expression, allowing a :term:`generator` to
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delegate
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part of its operations to another generator. This allows a section of code
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containing :keyword:`yield` to be factored out and placed in another generator.
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Additionally, the subgenerator is allowed to return with a value, and the
|
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value is made available to the delegating generator.
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While designed primarily for use in delegating to a subgenerator, the ``yield
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from`` expression actually allows delegation to arbitrary subiterators.
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For simple iterators, ``yield from iterable`` is essentially just a shortened
|
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form of ``for item in iterable: yield item``::
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>>> def g(x):
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... yield from range(x, 0, -1)
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... yield from range(x)
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...
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>>> list(g(5))
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[5, 4, 3, 2, 1, 0, 1, 2, 3, 4]
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However, unlike an ordinary loop, ``yield from`` allows subgenerators to
|
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receive sent and thrown values directly from the calling scope, and
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return a final value to the outer generator::
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>>> def accumulate():
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... tally = 0
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... while 1:
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... next = yield
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... if next is None:
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... return tally
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... tally += next
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...
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>>> def gather_tallies(tallies):
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... while 1:
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... tally = yield from accumulate()
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... tallies.append(tally)
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...
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>>> tallies = []
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>>> acc = gather_tallies(tallies)
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>>> next(acc) # Ensure the accumulator is ready to accept values
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>>> for i in range(4):
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... acc.send(i)
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...
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>>> acc.send(None) # Finish the first tally
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>>> for i in range(5):
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... acc.send(i)
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...
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>>> acc.send(None) # Finish the second tally
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>>> tallies
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[6, 10]
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The main principle driving this change is to allow even generators that are
|
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designed to be used with the ``send`` and ``throw`` methods to be split into
|
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multiple subgenerators as easily as a single large function can be split into
|
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multiple subfunctions.
|
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|
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.. seealso::
|
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|
|
:pep:`380` - Syntax for Delegating to a Subgenerator
|
|
PEP written by Greg Ewing; implementation by Greg Ewing, integrated into
|
|
3.3 by Renaud Blanch, Ryan Kelly and Nick Coghlan; documentation by
|
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Zbigniew Jędrzejewski-Szmek and Nick Coghlan
|
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|
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PEP 409: Suppressing exception context
|
|
======================================
|
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|
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::
|
|
|
|
>>> class D:
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... def __init__(self, extra):
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|
... self._extra_attributes = extra
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|
... def __getattr__(self, attr):
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... try:
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... return self._extra_attributes[attr]
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|
... except KeyError:
|
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... raise AttributeError(attr) from None
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...
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>>> D({}).x
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Traceback (most recent call last):
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File "<stdin>", line 1, in <module>
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File "<stdin>", line 8, in __getattr__
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AttributeError: x
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Without the ``from None`` suffix to suppress the cause, the original
|
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exception would be displayed by default::
|
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|
|
>>> class C:
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... def __init__(self, extra):
|
|
... self._extra_attributes = extra
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|
... def __getattr__(self, attr):
|
|
... try:
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... return self._extra_attributes[attr]
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... except KeyError:
|
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... raise AttributeError(attr)
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...
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>>> C({}).x
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Traceback (most recent call last):
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|
File "<stdin>", line 6, in __getattr__
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KeyError: 'x'
|
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|
|
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__
|
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AttributeError: x
|
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|
|
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
|
|
... except AttributeError as exc:
|
|
... print(repr(exc.__context__))
|
|
...
|
|
KeyError('x',)
|
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|
|
.. seealso::
|
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|
|
:pep:`409` - Suppressing exception context
|
|
PEP written by Ethan Furman; implemented by Ethan Furman and Nick
|
|
Coghlan.
|
|
|
|
|
|
PEP 414: Explicit Unicode literals
|
|
======================================
|
|
|
|
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).
|
|
|
|
.. seealso::
|
|
|
|
:pep:`414` - Explicit Unicode literals
|
|
PEP written by Armin Ronacher.
|
|
|
|
|
|
PEP 3155: Qualified name for classes and functions
|
|
==================================================
|
|
|
|
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::
|
|
|
|
>>> class C:
|
|
... def meth(self):
|
|
... pass
|
|
>>> C.meth.__name__
|
|
'meth'
|
|
>>> C.meth.__qualname__
|
|
'C.meth'
|
|
|
|
Example with nested classes::
|
|
|
|
>>> class C:
|
|
... class D:
|
|
... def meth(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::
|
|
|
|
>>> def outer():
|
|
... def inner():
|
|
... pass
|
|
... return inner
|
|
...
|
|
>>> 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>'
|
|
|
|
.. seealso::
|
|
|
|
:pep:`3155` - Qualified name for classes and functions
|
|
PEP written and implemented by Antoine Pitrou.
|
|
|
|
|
|
.. _pep-412:
|
|
|
|
PEP 412: Key-Sharing Dictionary
|
|
===============================
|
|
|
|
Dictionaries used for the storage of objects' attributes are now able to
|
|
share part of their internal storage between each other (namely, the part
|
|
which stores the keys and their respective hashes). This reduces the memory
|
|
consumption of programs creating many instances of non-builtin types.
|
|
|
|
.. seealso::
|
|
|
|
:pep:`412` - Key-Sharing Dictionary
|
|
PEP written and implemented by Mark Shannon.
|
|
|
|
|
|
PEP 362: Function Signature Object
|
|
==================================
|
|
|
|
A new function :func:`inspect.signature` makes introspection of python
|
|
callables easy and straightforward. A broad range of callables is supported:
|
|
python functions, decorated or not, classes, and :func:`functools.partial`
|
|
objects. New classes :class:`inspect.Signature`, :class:`inspect.Parameter`
|
|
and :class:`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.
|
|
|
|
.. seealso::
|
|
|
|
:pep:`362`: - Function Signature Object
|
|
PEP written by Brett Cannon, Yury Selivanov, Larry Hastings, Jiwon Seo;
|
|
implemented by Yury Selivanov.
|
|
|
|
|
|
PEP 421: Adding sys.implementation
|
|
==================================
|
|
|
|
A new attribute on the :mod:`sys` module exposes details specific to the
|
|
implementation of the currently running interpreter. The initial set of
|
|
attributes on :attr:`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 :mod:`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: :class:`types.SimpleNamespace`. In contrast to a mapping-based
|
|
namespace, like :class:`dict`, ``SimpleNamespace`` is attribute-based, like
|
|
:class:`object`. However, unlike ``object``, ``SimpleNamespace`` instances
|
|
are writable. This means that you can add, remove, and modify the namespace
|
|
through normal attribute access.
|
|
|
|
.. seealso::
|
|
|
|
:pep:`421` - Adding sys.implementation
|
|
PEP written and implemented by Eric Snow.
|
|
|
|
|
|
.. _importlib:
|
|
|
|
Using importlib as the Implementation of Import
|
|
===============================================
|
|
:issue:`2377` - Replace __import__ w/ importlib.__import__
|
|
:issue:`13959` - Re-implement parts of :mod:`imp` in pure Python
|
|
:issue:`14605` - Make import machinery explicit
|
|
:issue:`14646` - Require loaders set __loader__ and __package__
|
|
|
|
The :func:`__import__` function is now powered by :func:`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 :mod:`importlib` package.
|
|
|
|
The abstract base classes defined in :mod:`importlib.abc` have been expanded
|
|
to properly delineate between :term:`meta path finders <meta path finder>`
|
|
and :term:`path entry finders <path entry finder>` by introducing
|
|
:class:`importlib.abc.MetaPathFinder` and
|
|
:class:`importlib.abc.PathEntryFinder`, respectively. The old ABC of
|
|
:class:`importlib.abc.Finder` is now only provided for backwards-compatibility
|
|
and does not enforce any method requirements.
|
|
|
|
In terms of finders, :class:`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 :attr:`sys.path_hooks`.
|
|
|
|
For loaders, the new abstract base class :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
|
|
(:class:`importlib.machinery.SourceFileLoader`), sourceless bytecode files
|
|
(:class:`importlib.machinery.SourcelessFileLoader`), and extension modules
|
|
(:class:`importlib.machinery.ExtensionFileLoader`) are now available for
|
|
direct use.
|
|
|
|
:exc:`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 :func:`importlib.invalidate_caches` function will now call the method with
|
|
the same name on all finders cached in :attr:`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 :mod:`importlib` now exposes, there are other
|
|
visible changes to import. The biggest is that :attr:`sys.meta_path` and
|
|
:attr:`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 :mod:`importlib` and import itself is setting the attribute post-load.
|
|
|
|
``None`` is now inserted into :attr:`sys.path_importer_cache` when no finder
|
|
can be found on :attr:`sys.path_hooks`. Since :class:`imp.NullImporter` is not
|
|
directly exposed on :attr:`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)
|
|
|
|
|
|
Other Language Changes
|
|
======================
|
|
|
|
Some smaller changes made to the core Python language are:
|
|
|
|
* Added support for Unicode name aliases and named sequences.
|
|
Both :func:`unicodedata.lookup()` and ``'\N{...}'`` now resolve name aliases,
|
|
and :func:`unicodedata.lookup()` resolves named sequences too.
|
|
|
|
(Contributed by Ezio Melotti in :issue:`12753`.)
|
|
|
|
* Unicode database updated to UCD version 6.1.0
|
|
|
|
* Equality comparisons on :func:`range` objects now return a result reflecting
|
|
the equality of the underlying sequences generated by those range objects.
|
|
(:issue:`13201`)
|
|
|
|
* The ``count()``, ``find()``, ``rfind()``, ``index()`` and ``rindex()``
|
|
methods of :class:`bytes` and :class:`bytearray` objects now accept an
|
|
integer between 0 and 255 as their first argument.
|
|
|
|
(Contributed by Petri Lehtinen in :issue:`12170`.)
|
|
|
|
* The ``rjust()``, ``ljust()``, and ``center()`` methods of :class:`bytes`
|
|
and :class:`bytearray` now accept a :class:`bytearray` for the ``fill``
|
|
argument. (Contributed by Petri Lehtinen in :issue:`12380`.)
|
|
|
|
* New methods have been added to :class:`list` and :class:`bytearray`:
|
|
``copy()`` and ``clear()`` (:issue:`10516`). Consequently,
|
|
:class:`~collections.abc.MutableSequence` now also defines a
|
|
:meth:`~collections.abc.MutableSequence.clear` method (:issue:`11388`).
|
|
|
|
* Raw bytes literals can now be written ``rb"..."`` as well as ``br"..."``.
|
|
|
|
(Contributed by Antoine Pitrou in :issue:`13748`.)
|
|
|
|
* :meth:`dict.setdefault` now does only one lookup for the given key, making
|
|
it atomic when used with built-in types.
|
|
|
|
(Contributed by Filip Gruszczyński in :issue:`13521`.)
|
|
|
|
* The error messages produced when a function call does not match the function
|
|
signature have been significantly improved.
|
|
|
|
(Contributed by Benjamin Peterson.)
|
|
|
|
|
|
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
|
|
:c:func:`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.
|
|
|
|
(Contributed by Antoine Pitrou in :issue:`9260`.)
|
|
|
|
|
|
Builtin functions and types
|
|
===========================
|
|
|
|
* :func:`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 :data:`os.O_CLOEXEC` for
|
|
example. The ``'x'`` mode was added: open for exclusive creation, failing if
|
|
the file already exists.
|
|
* :func:`print`: added the *flush* keyword argument. If the *flush* keyword
|
|
argument is true, the stream is forcibly flushed.
|
|
* :func:`hash`: hash randomization is enabled by default, see
|
|
:meth:`object.__hash__` and :envvar:`PYTHONHASHSEED`.
|
|
* The :class:`str` type gets a new :meth:`~str.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
|
|
(:issue:`4966`).
|
|
|
|
|
|
New Modules
|
|
===========
|
|
|
|
faulthandler
|
|
------------
|
|
|
|
This new debug module :mod:`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 :func:`faulthandler.enable` to install fault handlers for the
|
|
:const:`SIGSEGV`, :const:`SIGFPE`, :const:`SIGABRT`, :const:`SIGBUS`, and
|
|
:const:`SIGILL` signals. You can also enable them at startup by setting the
|
|
:envvar:`PYTHONFAULTHANDLER` environment variable or by using :option:`-X`
|
|
``faulthandler`` command line option.
|
|
|
|
Example of a segmentation fault on Linux:
|
|
|
|
.. code-block:: shell-session
|
|
|
|
$ 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 :mod:`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).
|
|
|
|
(Contributed by Google and Peter Moody in :pep:`3144`.)
|
|
|
|
lzma
|
|
----
|
|
|
|
The newly-added :mod:`lzma` module provides data compression and decompression
|
|
using the LZMA algorithm, including support for the ``.xz`` and ``.lzma``
|
|
file formats.
|
|
|
|
(Contributed by Nadeem Vawda and Per Øyvind Karlsen in :issue:`6715`.)
|
|
|
|
|
|
Improved Modules
|
|
================
|
|
|
|
abc
|
|
---
|
|
|
|
Improved support for abstract base classes containing descriptors composed with
|
|
abstract methods. The recommended approach to declaring abstract descriptors is
|
|
now to provide :attr:`__isabstractmethod__` as a dynamically updated
|
|
property. The built-in descriptors have been updated accordingly.
|
|
|
|
* :class:`abc.abstractproperty` has been deprecated, use :class:`property`
|
|
with :func:`abc.abstractmethod` instead.
|
|
* :class:`abc.abstractclassmethod` has been deprecated, use
|
|
:class:`classmethod` with :func:`abc.abstractmethod` instead.
|
|
* :class:`abc.abstractstaticmethod` has been deprecated, use
|
|
:class:`staticmethod` with :func:`abc.abstractmethod` instead.
|
|
|
|
(Contributed by Darren Dale in :issue:`11610`.)
|
|
|
|
:meth:`abc.ABCMeta.register` now returns the registered subclass, which means
|
|
it can now be used as a class decorator (:issue:`10868`).
|
|
|
|
|
|
array
|
|
-----
|
|
|
|
The :mod:`array` module supports the :c:type:`long long` type using ``q`` and
|
|
``Q`` type codes.
|
|
|
|
(Contributed by Oren Tirosh and Hirokazu Yamamoto in :issue:`1172711`.)
|
|
|
|
|
|
base64
|
|
------
|
|
|
|
ASCII-only Unicode strings are now accepted by the decoding functions of the
|
|
:mod:`base64` modern interface. For example, ``base64.b64decode('YWJj')``
|
|
returns ``b'abc'``. (Contributed by Catalin Iacob in :issue:`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 :issue:`13637`.)
|
|
|
|
|
|
bz2
|
|
---
|
|
|
|
The :mod:`bz2` module has been rewritten from scratch. In the process, several
|
|
new features have been added:
|
|
|
|
* New :func:`bz2.open` function: open a bzip2-compressed file in binary or
|
|
text mode.
|
|
|
|
* :class:`bz2.BZ2File` can now read from and write to arbitrary file-like
|
|
objects, by means of its constructor's *fileobj* argument.
|
|
|
|
(Contributed by Nadeem Vawda in :issue:`5863`.)
|
|
|
|
* :class:`bz2.BZ2File` and :func:`bz2.decompress` can now decompress
|
|
multi-stream inputs (such as those produced by the :program:`pbzip2` tool).
|
|
:class:`bz2.BZ2File` can now also be used to create this type of file, using
|
|
the ``'a'`` (append) mode.
|
|
|
|
(Contributed by Nir Aides in :issue:`1625`.)
|
|
|
|
* :class:`bz2.BZ2File` now implements all of the :class:`io.BufferedIOBase` API,
|
|
except for the :meth:`detach` and :meth:`truncate` methods.
|
|
|
|
|
|
codecs
|
|
------
|
|
|
|
The :mod:`~encodings.mbcs` codec has been rewritten to handle correctly
|
|
``replace`` and ``ignore`` error handlers on all Windows versions. The
|
|
:mod:`~encodings.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`` (:issue:`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
|
|
``chcp 65001`` 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.
|
|
|
|
(:issue:`12016`)
|
|
|
|
Incremental CJK codec encoders are no longer reset at each call to their
|
|
encode() methods. For example::
|
|
|
|
>>> import codecs
|
|
>>> encoder = codecs.getincrementalencoder('hz')('strict')
|
|
>>> b''.join(encoder.encode(x) for x in '\u52ff\u65bd\u65bc\u4eba\u3002 Bye.')
|
|
b'~{NpJ)l6HK!#~} Bye.'
|
|
|
|
This example gives ``b'~{Np~}~{J)~}~{l6~}~{HK~}~{!#~} Bye.'`` with older Python
|
|
versions.
|
|
|
|
(:issue:`12100`)
|
|
|
|
The ``unicode_internal`` codec has been deprecated.
|
|
|
|
|
|
collections
|
|
-----------
|
|
|
|
Addition of a new :class:`~collections.ChainMap` class to allow treating a
|
|
number of mappings as a single unit. (Written by Raymond Hettinger for
|
|
:issue:`11089`, made public in :issue:`11297`.)
|
|
|
|
The abstract base classes have been moved in a new :mod:`collections.abc`
|
|
module, to better differentiate between the abstract and the concrete
|
|
collections classes. Aliases for ABCs are still present in the
|
|
:mod:`collections` module to preserve existing imports. (:issue:`11085`)
|
|
|
|
.. XXX addition of __slots__ to ABCs not recorded here: internal detail
|
|
|
|
The :class:`~collections.Counter` class now supports the unary ``+`` and ``-``
|
|
operators, as well as the in-place operators ``+=``, ``-=``, ``|=``, and
|
|
``&=``. (Contributed by Raymond Hettinger in :issue:`13121`.)
|
|
|
|
|
|
contextlib
|
|
----------
|
|
|
|
:class:`~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
|
|
:mod:`threading` module).
|
|
|
|
(:issue:`13585`)
|
|
|
|
|
|
crypt
|
|
-----
|
|
|
|
Addition of salt and modular crypt format (hashing method) and the :func:`~crypt.mksalt`
|
|
function to the :mod:`crypt` module.
|
|
|
|
(:issue:`10924`)
|
|
|
|
curses
|
|
------
|
|
|
|
* If the :mod:`curses` module is linked to the ncursesw library, use Unicode
|
|
functions when Unicode strings or characters are passed (e.g.
|
|
:c:func:`waddwstr`), and bytes functions otherwise (e.g. :c:func:`waddstr`).
|
|
* Use the locale encoding instead of ``utf-8`` to encode Unicode strings.
|
|
* :class:`curses.window` has a new :attr:`curses.window.encoding` attribute.
|
|
* The :class:`curses.window` class has a new :meth:`~curses.window.get_wch`
|
|
method to get a wide character
|
|
* The :mod:`curses` module has a new :meth:`~curses.unget_wch` function to
|
|
push a wide character so the next :meth:`~curses.window.get_wch` will return
|
|
it
|
|
|
|
(Contributed by Iñigo Serna in :issue:`6755`.)
|
|
|
|
datetime
|
|
--------
|
|
|
|
* Equality comparisons between naive and aware :class:`~datetime.datetime`
|
|
instances now return :const:`False` instead of raising :exc:`TypeError`
|
|
(:issue:`15006`).
|
|
* New :meth:`datetime.datetime.timestamp` method: Return POSIX timestamp
|
|
corresponding to the :class:`~datetime.datetime` instance.
|
|
* The :meth:`datetime.datetime.strftime` method supports formatting years
|
|
older than 1000.
|
|
* The :meth:`datetime.datetime.astimezone` method can now be
|
|
called without arguments to convert datetime instance to the system
|
|
timezone.
|
|
|
|
|
|
.. _new-decimal:
|
|
|
|
decimal
|
|
-------
|
|
|
|
:issue:`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 | speedup |
|
|
+=========+=============+==============+=============+
|
|
| pi | 42.02s | 0.345s | 120x |
|
|
+---------+-------------+--------------+-------------+
|
|
| telco | 172.19s | 5.68s | 30x |
|
|
+---------+-------------+--------------+-------------+
|
|
| psycopg | 3.57s | 0.29s | 12x |
|
|
+---------+-------------+--------------+-------------+
|
|
|
|
Features
|
|
~~~~~~~~
|
|
|
|
* The :exc:`~decimal.FloatOperation` signal optionally enables stricter
|
|
semantics for mixing floats and Decimals.
|
|
|
|
* If Python is compiled without threads, the C version automatically
|
|
disables the expensive thread local context machinery. In this case,
|
|
the variable :data:`~decimal.HAVE_THREADS` is set to ``False``.
|
|
|
|
API changes
|
|
~~~~~~~~~~~
|
|
|
|
* The C module has the following context limits, depending on the machine
|
|
architecture:
|
|
|
|
+-------------------+---------------------+------------------------------+
|
|
| | 32-bit | 64-bit |
|
|
+===================+=====================+==============================+
|
|
| :const:`MAX_PREC` | :const:`425000000` | :const:`999999999999999999` |
|
|
+-------------------+---------------------+------------------------------+
|
|
| :const:`MAX_EMAX` | :const:`425000000` | :const:`999999999999999999` |
|
|
+-------------------+---------------------+------------------------------+
|
|
| :const:`MIN_EMIN` | :const:`-425000000` | :const:`-999999999999999999` |
|
|
+-------------------+---------------------+------------------------------+
|
|
|
|
* In the context templates (:class:`~decimal.DefaultContext`,
|
|
:class:`~decimal.BasicContext` and :class:`~decimal.ExtendedContext`)
|
|
the magnitude of :attr:`~decimal.Context.Emax` and
|
|
:attr:`~decimal.Context.Emin` has changed to :const:`999999`.
|
|
|
|
* The :class:`~decimal.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
|
|
:exc:`~decimal.InvalidOperation` is raised and the result is NaN. In the
|
|
latter case it is always possible to use :meth:`~decimal.Context.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
|
|
:meth:`~decimal.Decimal.exp` and :meth:`~decimal.Decimal.ln` functions,
|
|
but the final result is only "almost always correctly rounded".
|
|
|
|
|
|
* In the C version, the context dictionary containing the signals is a
|
|
:class:`~collections.abc.MutableMapping`. For speed reasons,
|
|
:attr:`~decimal.Context.flags` and :attr:`~decimal.Context.traps` always
|
|
refer to the same :class:`~collections.abc.MutableMapping` that the context
|
|
was initialized with. If a new signal dictionary is assigned,
|
|
:attr:`~decimal.Context.flags` and :attr:`~decimal.Context.traps`
|
|
are updated with the new values, but they do not reference the RHS
|
|
dictionary.
|
|
|
|
|
|
* Pickling a :class:`~decimal.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 :class:`~decimal.Context` constructor has been
|
|
changed to match the order displayed by :func:`repr`.
|
|
|
|
|
|
* The ``watchexp`` parameter in the :meth:`~decimal.Decimal.quantize` method
|
|
is deprecated.
|
|
|
|
|
|
.. _new-email:
|
|
|
|
email
|
|
-----
|
|
|
|
Policy Framework
|
|
~~~~~~~~~~~~~~~~
|
|
|
|
The email package now has a :mod:`~email.policy` framework. A
|
|
:class:`~email.policy.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 :class:`~email.policy.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 :mod:`~email.parser`, or when a
|
|
:class:`~email.message.Message` object is created, or when an email is
|
|
serialized using a :mod:`~email.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
|
|
:data:`~email.policy.compat32`.
|
|
|
|
The minimum set of controls implemented by all ``policy`` objects are:
|
|
|
|
.. tabularcolumns:: |l|L|
|
|
|
|
=============== =======================================================
|
|
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
|
|
``Bytes`` ``generator``, 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
|
|
:meth:`~email.policy.Policy.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 :term:`provisional policy
|
|
<provisional package>`. 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 :class:`~email.policy.EmailPolicy`,
|
|
and add the following additional controls:
|
|
|
|
.. tabularcolumns:: |l|L|
|
|
|
|
=============== =======================================================
|
|
refold_source Controls whether or not headers parsed by a
|
|
:mod:`~email.parser` are refolded by the
|
|
:mod:`~email.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 :mod:`email.header` :meth:`~email.header.decode_header` or
|
|
:meth:`~email.header.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 :class:`~email.parser.BytesHeaderParser`, added to the :mod:`~email.parser`
|
|
module to complement :class:`~email.parser.HeaderParser` and complete the Bytes
|
|
API.
|
|
|
|
New utility functions:
|
|
|
|
* :func:`~email.utils.format_datetime`: given a :class:`~datetime.datetime`,
|
|
produce a string formatted for use in an email header.
|
|
|
|
* :func:`~email.utils.parsedate_to_datetime`: given a date string from
|
|
an email header, convert it into an aware :class:`~datetime.datetime`,
|
|
or a naive :class:`~datetime.datetime` if the offset is ``-0000``.
|
|
|
|
* :func:`~email.utils.localtime`: With no argument, returns the
|
|
current local time as an aware :class:`~datetime.datetime` using the local
|
|
:class:`~datetime.timezone`. Given an aware :class:`~datetime.datetime`,
|
|
converts it into an aware :class:`~datetime.datetime` using the
|
|
local :class:`~datetime.timezone`.
|
|
|
|
|
|
ftplib
|
|
------
|
|
|
|
* :class:`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 :issue:`8594`.)
|
|
|
|
* The :class:`~ftplib.FTP_TLS` class now provides a new
|
|
:func:`~ftplib.FTP_TLS.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 :issue:`12139`.)
|
|
|
|
* Added :meth:`ftplib.FTP.mlsd` method which provides a parsable directory
|
|
listing format and deprecates :meth:`ftplib.FTP.nlst` and
|
|
:meth:`ftplib.FTP.dir`. (Contributed by Giampaolo Rodolà in :issue:`11072`.)
|
|
|
|
|
|
functools
|
|
---------
|
|
|
|
The :func:`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 :issue:`13227`.)
|
|
|
|
|
|
gc
|
|
--
|
|
|
|
It is now possible to register callbacks invoked by the garbage collector
|
|
before and after collection using the new :data:`~gc.callbacks` list.
|
|
|
|
|
|
hmac
|
|
----
|
|
|
|
A new :func:`~hmac.compare_digest` function has been added to prevent side
|
|
channel attacks on digests through timing analysis. (Contributed by Nick
|
|
Coghlan and Christian Heimes in :issue:`15061`.)
|
|
|
|
|
|
http
|
|
----
|
|
|
|
:class:`http.server.BaseHTTPRequestHandler` now buffers the headers and writes
|
|
them all at once when :meth:`~http.server.BaseHTTPRequestHandler.end_headers` is
|
|
called. A new method :meth:`~http.server.BaseHTTPRequestHandler.flush_headers`
|
|
can be used to directly manage when the accumulated headers are sent.
|
|
(Contributed by Andrew Schaaf in :issue:`3709`.)
|
|
|
|
:class:`http.server` now produces valid ``HTML 4.01 strict`` output.
|
|
(Contributed by Ezio Melotti in :issue:`13295`.)
|
|
|
|
:class:`http.client.HTTPResponse` now has a
|
|
:meth:`~http.client.HTTPResponse.readinto` method, which means it can be used
|
|
as an :class:`io.RawIOBase` class. (Contributed by John Kuhn in
|
|
:issue:`13464`.)
|
|
|
|
|
|
html
|
|
----
|
|
|
|
:class:`html.parser.HTMLParser` is now able to parse broken markup without
|
|
raising errors, therefore the *strict* argument of the constructor and the
|
|
:exc:`~html.parser.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 :issue:`15114`, and :issue:`14538`,
|
|
:issue:`13993`, :issue:`13960`, :issue:`13358`, :issue:`1745761`,
|
|
:issue:`755670`, :issue:`13357`, :issue:`12629`, :issue:`1200313`,
|
|
:issue:`670664`, :issue:`13273`, :issue:`12888`, :issue:`7311`.)
|
|
|
|
A new :data:`~html.entities.html5` dictionary that maps HTML5 named character
|
|
references to the equivalent Unicode character(s) (e.g. ``html5['gt;'] ==
|
|
'>'``) has been added to the :mod:`html.entities` module. The dictionary is
|
|
now also used by :class:`~html.parser.HTMLParser`. (Contributed by Ezio
|
|
Melotti in :issue:`11113` and :issue:`15156`.)
|
|
|
|
|
|
imaplib
|
|
-------
|
|
|
|
The :class:`~imaplib.IMAP4_SSL` constructor now accepts an SSLContext
|
|
parameter to control parameters of the secure channel.
|
|
|
|
(Contributed by Sijin Joseph in :issue:`8808`.)
|
|
|
|
|
|
inspect
|
|
-------
|
|
|
|
A new :func:`~inspect.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.
|
|
|
|
(Contributed by Meador Inge and Nick Coghlan in :issue:`13062`.)
|
|
|
|
A new :func:`~inspect.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.
|
|
|
|
(Contributed by Meador Inge in :issue:`15153`.)
|
|
|
|
io
|
|
--
|
|
|
|
The :func:`~io.open` function has a new ``'x'`` mode that can be used to
|
|
exclusively create a new file, and raise a :exc:`FileExistsError` if the file
|
|
already exists. It is based on the C11 'x' mode to fopen().
|
|
|
|
(Contributed by David Townshend in :issue:`12760`.)
|
|
|
|
The constructor of the :class:`~io.TextIOWrapper` class has a new
|
|
*write_through* optional argument. If *write_through* is ``True``, calls to
|
|
:meth:`~io.TextIOWrapper.write` are guaranteed not to be buffered: any data
|
|
written on the :class:`~io.TextIOWrapper` object is immediately handled to its
|
|
underlying binary buffer.
|
|
|
|
|
|
itertools
|
|
---------
|
|
|
|
:func:`~itertools.accumulate` now takes an optional ``func`` argument for
|
|
providing a user-supplied binary function.
|
|
|
|
|
|
logging
|
|
-------
|
|
|
|
The :func:`~logging.basicConfig` function now supports an optional ``handlers``
|
|
argument taking an iterable of handlers to be added to the root logger.
|
|
|
|
A class level attribute :attr:`~logging.handlers.SysLogHandler.append_nul` has
|
|
been added to :class:`~logging.handlers.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 :mod:`math` module has a new function, :func:`~math.log2`, which returns
|
|
the base-2 logarithm of *x*.
|
|
|
|
(Written by Mark Dickinson in :issue:`11888`.)
|
|
|
|
|
|
mmap
|
|
----
|
|
|
|
The :meth:`~mmap.mmap.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 :issue:`12021`.)
|
|
|
|
|
|
multiprocessing
|
|
---------------
|
|
|
|
The new :func:`multiprocessing.connection.wait` function allows polling
|
|
multiple objects (such as connections, sockets and pipes) with a timeout.
|
|
(Contributed by Richard Oudkerk in :issue:`12328`.)
|
|
|
|
:class:`multiprocessing.Connection` objects can now be transferred over
|
|
multiprocessing connections.
|
|
(Contributed by Richard Oudkerk in :issue:`4892`.)
|
|
|
|
:class:`multiprocessing.Process` now accepts a ``daemon`` keyword argument
|
|
to override the default behavior of inheriting the ``daemon`` flag from
|
|
the parent process (:issue:`6064`).
|
|
|
|
New attribute :data:`multiprocessing.Process.sentinel` allows a
|
|
program to wait on multiple :class:`~multiprocessing.Process` objects at one
|
|
time using the appropriate OS primitives (for example, :mod:`select` on
|
|
posix systems).
|
|
|
|
New methods :meth:`multiprocessing.pool.Pool.starmap` and
|
|
:meth:`~multiprocessing.pool.Pool.starmap_async` provide
|
|
:func:`itertools.starmap` equivalents to the existing
|
|
:meth:`multiprocessing.pool.Pool.map` and
|
|
:meth:`~multiprocessing.pool.Pool.map_async` functions. (Contributed by Hynek
|
|
Schlawack in :issue:`12708`.)
|
|
|
|
|
|
nntplib
|
|
-------
|
|
|
|
The :class:`nntplib.NNTP` class now supports the context management protocol to
|
|
unconditionally consume :exc:`socket.error` exceptions and to close the NNTP
|
|
connection when done::
|
|
|
|
>>> from nntplib import NNTP
|
|
>>> with NNTP('news.gmane.org') as n:
|
|
... n.group('gmane.comp.python.committers')
|
|
...
|
|
('211 1755 1 1755 gmane.comp.python.committers', 1755, 1, 1755, 'gmane.comp.python.committers')
|
|
>>>
|
|
|
|
(Contributed by Giampaolo Rodolà in :issue:`9795`.)
|
|
|
|
|
|
os
|
|
--
|
|
|
|
* The :mod:`os` module has a new :func:`~os.pipe2` function that makes it
|
|
possible to create a pipe with :data:`~os.O_CLOEXEC` or
|
|
:data:`~os.O_NONBLOCK` flags set atomically. This is especially useful to
|
|
avoid race conditions in multi-threaded programs.
|
|
|
|
* The :mod:`os` module has a new :func:`~os.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. :func:`~os.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 :issue:`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 (:issue:`4761`,
|
|
:issue:`10755` and :issue:`14626`).
|
|
|
|
- The :mod:`os` module has a new :func:`~os.fwalk` function similar to
|
|
:func:`~os.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* (:ref:`paths relative to
|
|
directory descriptors <dir_fd>`) and/or *follow_symlinks* (:ref:`not
|
|
following symlinks <follow_symlinks>`):
|
|
:func:`~os.access`, :func:`~os.chflags`, :func:`~os.chmod`, :func:`~os.chown`,
|
|
:func:`~os.link`, :func:`~os.lstat`, :func:`~os.mkdir`, :func:`~os.mkfifo`,
|
|
:func:`~os.mknod`, :func:`~os.open`, :func:`~os.readlink`, :func:`~os.remove`,
|
|
:func:`~os.rename`, :func:`~os.replace`, :func:`~os.rmdir`, :func:`~os.stat`,
|
|
:func:`~os.symlink`, :func:`~os.unlink`, :func:`~os.utime`. Platform
|
|
support for using these parameters can be checked via the sets
|
|
:data:`os.supports_dir_fd` and :data:`os.supports_follows_symlinks`.
|
|
|
|
- The following functions now support a file descriptor for their path argument:
|
|
:func:`~os.chdir`, :func:`~os.chmod`, :func:`~os.chown`,
|
|
:func:`~os.execve`, :func:`~os.listdir`, :func:`~os.pathconf`, :func:`~os.path.exists`,
|
|
:func:`~os.stat`, :func:`~os.statvfs`, :func:`~os.utime`. Platform support
|
|
for this can be checked via the :data:`os.supports_fd` set.
|
|
|
|
* :func:`~os.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
|
|
:data:`~os.supports_effective_ids` set.
|
|
|
|
* The :mod:`os` module has two new functions: :func:`~os.getpriority` and
|
|
:func:`~os.setpriority`. They can be used to get or set process
|
|
niceness/priority in a fashion similar to :func:`os.nice` but extended to all
|
|
processes instead of just the current one.
|
|
|
|
(Patch submitted by Giampaolo Rodolà in :issue:`10784`.)
|
|
|
|
* The new :func:`os.replace` function allows cross-platform renaming of a
|
|
file with overwriting the destination. With :func:`os.rename`, an existing
|
|
destination file is overwritten under POSIX, but raises an error under
|
|
Windows.
|
|
(Contributed by Antoine Pitrou in :issue:`8828`.)
|
|
|
|
* The stat family of functions (:func:`~os.stat`, :func:`~os.fstat`,
|
|
and :func:`~os.lstat`) now support reading a file's timestamps
|
|
with nanosecond precision. Symmetrically, :func:`~os.utime`
|
|
can now write file timestamps with nanosecond precision. (Contributed by
|
|
Larry Hastings in :issue:`14127`.)
|
|
|
|
* The new :func:`os.get_terminal_size` function queries the size of the
|
|
terminal attached to a file descriptor. See also
|
|
:func:`shutil.get_terminal_size`.
|
|
(Contributed by Zbigniew Jędrzejewski-Szmek in :issue:`13609`.)
|
|
|
|
.. XXX sort out this mess after beta1
|
|
|
|
* New functions to support Linux extended attributes (:issue:`12720`):
|
|
:func:`~os.getxattr`, :func:`~os.listxattr`, :func:`~os.removexattr`,
|
|
:func:`~os.setxattr`.
|
|
|
|
* New interface to the scheduler. These functions
|
|
control how a process is allocated CPU time by the operating system. New
|
|
functions:
|
|
:func:`~os.sched_get_priority_max`, :func:`~os.sched_get_priority_min`,
|
|
:func:`~os.sched_getaffinity`, :func:`~os.sched_getparam`,
|
|
:func:`~os.sched_getscheduler`, :func:`~os.sched_rr_get_interval`,
|
|
:func:`~os.sched_setaffinity`, :func:`~os.sched_setparam`,
|
|
:func:`~os.sched_setscheduler`, :func:`~os.sched_yield`,
|
|
|
|
* New functions to control the file system:
|
|
|
|
* :func:`~os.posix_fadvise`: Announces an intention to access data in a
|
|
specific pattern thus allowing the kernel to make optimizations.
|
|
* :func:`~os.posix_fallocate`: Ensures that enough disk space is allocated
|
|
for a file.
|
|
* :func:`~os.sync`: Force write of everything to disk.
|
|
|
|
* Additional new posix functions:
|
|
|
|
* :func:`~os.lockf`: Apply, test or remove a POSIX lock on an open file descriptor.
|
|
* :func:`~os.pread`: Read from a file descriptor at an offset, the file
|
|
offset remains unchanged.
|
|
* :func:`~os.pwrite`: Write to a file descriptor from an offset, leaving
|
|
the file offset unchanged.
|
|
* :func:`~os.readv`: Read from a file descriptor into a number of writable buffers.
|
|
* :func:`~os.truncate`: Truncate the file corresponding to *path*, so that
|
|
it is at most *length* bytes in size.
|
|
* :func:`~os.waitid`: Wait for the completion of one or more child processes.
|
|
* :func:`~os.writev`: Write the contents of *buffers* to a file descriptor,
|
|
where *buffers* is an arbitrary sequence of buffers.
|
|
* :func:`~os.getgrouplist` (:issue:`9344`): Return list of group ids that
|
|
specified user belongs to.
|
|
|
|
* :func:`~os.times` and :func:`~os.uname`: Return type changed from a tuple to
|
|
a tuple-like object with named attributes.
|
|
|
|
* Some platforms now support additional constants for the :func:`~os.lseek`
|
|
function, such as ``os.SEEK_HOLE`` and ``os.SEEK_DATA``.
|
|
|
|
* New constants :data:`~os.RTLD_LAZY`, :data:`~os.RTLD_NOW`,
|
|
:data:`~os.RTLD_GLOBAL`, :data:`~os.RTLD_LOCAL`, :data:`~os.RTLD_NODELETE`,
|
|
:data:`~os.RTLD_NOLOAD`, and :data:`~os.RTLD_DEEPBIND` are available on
|
|
platforms that support them. These are for use with the
|
|
:func:`sys.setdlopenflags` function, and supersede the similar constants
|
|
defined in :mod:`ctypes` and :mod:`DLFCN`. (Contributed by Victor Stinner
|
|
in :issue:`13226`.)
|
|
|
|
* :func:`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.
|
|
|
|
(Contributed by Georg Brandl in :issue:`14210`)
|
|
|
|
|
|
pickle
|
|
------
|
|
|
|
:class:`pickle.Pickler` objects now have an optional
|
|
:attr:`~pickle.Pickler.dispatch_table` attribute allowing per-pickler
|
|
reduction functions to be set.
|
|
|
|
(Contributed by Richard Oudkerk in :issue:`14166`.)
|
|
|
|
|
|
pydoc
|
|
-----
|
|
|
|
The Tk GUI and the :func:`~pydoc.serve` function have been removed from the
|
|
:mod:`pydoc` module: ``pydoc -g`` and :func:`~pydoc.serve` have been deprecated
|
|
in Python 3.2.
|
|
|
|
|
|
re
|
|
--
|
|
|
|
:class:`str` regular expressions now support ``\u`` and ``\U`` escapes.
|
|
|
|
(Contributed by Serhiy Storchaka in :issue:`3665`.)
|
|
|
|
|
|
sched
|
|
-----
|
|
|
|
* :meth:`~sched.scheduler.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 :class:`~sched.scheduler` in
|
|
non-blocking applications. (Contributed by Giampaolo Rodolà in :issue:`13449`.)
|
|
|
|
* :class:`~sched.scheduler` class can now be safely used in multi-threaded
|
|
environments. (Contributed by Josiah Carlson and Giampaolo Rodolà in
|
|
:issue:`8684`.)
|
|
|
|
* *timefunc* and *delayfunct* parameters of :class:`~sched.scheduler` class
|
|
constructor are now optional and defaults to :func:`time.time` and
|
|
:func:`time.sleep` respectively. (Contributed by Chris Clark in
|
|
:issue:`13245`.)
|
|
|
|
* :meth:`~sched.scheduler.enter` and :meth:`~sched.scheduler.enterabs`
|
|
*argument* parameter is now optional. (Contributed by Chris Clark in
|
|
:issue:`13245`.)
|
|
|
|
* :meth:`~sched.scheduler.enter` and :meth:`~sched.scheduler.enterabs`
|
|
now accept a *kwargs* parameter. (Contributed by Chris Clark in
|
|
:issue:`13245`.)
|
|
|
|
|
|
select
|
|
------
|
|
|
|
Solaris and derivative platforms have a new class :class:`select.devpoll`
|
|
for high performance asynchronous sockets via :file:`/dev/poll`.
|
|
(Contributed by Jesús Cea Avión in :issue:`6397`.)
|
|
|
|
|
|
shlex
|
|
-----
|
|
|
|
The previously undocumented helper function ``quote`` from the
|
|
:mod:`pipes` modules has been moved to the :mod:`shlex` module and
|
|
documented. :func:`~shlex.quote` properly escapes all characters in a string
|
|
that might be otherwise given special meaning by the shell.
|
|
|
|
|
|
shutil
|
|
------
|
|
|
|
* New functions:
|
|
|
|
* :func:`~shutil.disk_usage`: provides total, used and free disk space
|
|
statistics. (Contributed by Giampaolo Rodolà in :issue:`12442`.)
|
|
* :func:`~shutil.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 :issue:`12191`.)
|
|
* :func:`shutil.get_terminal_size`: returns the size of the terminal window
|
|
to which the interpreter is attached. (Contributed by Zbigniew
|
|
Jędrzejewski-Szmek in :issue:`13609`.)
|
|
|
|
* :func:`~shutil.copy2` and :func:`~shutil.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 :issue:`14127` and :issue:`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 :issue:`12715`.)
|
|
|
|
* When copying files to a different file system, :func:`~shutil.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 :issue:`9993`.) :func:`~shutil.move` now also returns
|
|
the ``dst`` argument as its result.
|
|
|
|
* :func:`~shutil.rmtree` is now resistant to symlink attacks on platforms
|
|
which support the new ``dir_fd`` parameter in :func:`os.open` and
|
|
:func:`os.unlink`. (Contributed by Martin von Löwis and Hynek Schlawack
|
|
in :issue:`4489`.)
|
|
|
|
|
|
signal
|
|
------
|
|
|
|
* The :mod:`signal` module has new functions:
|
|
|
|
* :func:`~signal.pthread_sigmask`: fetch and/or change the signal mask of the
|
|
calling thread (Contributed by Jean-Paul Calderone in :issue:`8407`);
|
|
* :func:`~signal.pthread_kill`: send a signal to a thread;
|
|
* :func:`~signal.sigpending`: examine pending functions;
|
|
* :func:`~signal.sigwait`: wait a signal;
|
|
* :func:`~signal.sigwaitinfo`: wait for a signal, returning detailed
|
|
information about it;
|
|
* :func:`~signal.sigtimedwait`: like :func:`~signal.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.
|
|
|
|
* :func:`signal.signal` and :func:`signal.siginterrupt` raise an OSError,
|
|
instead of a RuntimeError: OSError has an errno attribute.
|
|
|
|
|
|
smtpd
|
|
-----
|
|
|
|
The :mod:`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. :issue:`8739`)
|
|
|
|
|
|
smtplib
|
|
-------
|
|
|
|
The :class:`~smtplib.SMTP`, :class:`~smtplib.SMTP_SSL`, and
|
|
:class:`~smtplib.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
|
|
:issue:`11281`.)
|
|
|
|
:class:`~smtplib.SMTP` now supports the context management protocol, allowing an
|
|
``SMTP`` instance to be used in a ``with`` statement. (Contributed
|
|
by Giampaolo Rodolà in :issue:`11289`.)
|
|
|
|
The :class:`~smtplib.SMTP_SSL` constructor and the :meth:`~smtplib.SMTP.starttls`
|
|
method now accept an SSLContext parameter to control parameters of the secure
|
|
channel. (Contributed by Kasun Herath in :issue:`8809`.)
|
|
|
|
|
|
socket
|
|
------
|
|
|
|
* The :class:`~socket.socket` class now exposes additional methods to process
|
|
ancillary data when supported by the underlying platform:
|
|
|
|
* :func:`~socket.socket.sendmsg`
|
|
* :func:`~socket.socket.recvmsg`
|
|
* :func:`~socket.socket.recvmsg_into`
|
|
|
|
(Contributed by David Watson in :issue:`6560`, based on an earlier patch by
|
|
Heiko Wundram)
|
|
|
|
* The :class:`~socket.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 :issue:`10141`.)
|
|
|
|
* The :class:`~socket.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 :class:`~socket.socket` class now supports the ``PF_SYSTEM`` protocol
|
|
family on OS X. (Contributed by Michael Goderbauer in :issue:`13777`.)
|
|
|
|
* New function :func:`~socket.sethostname` allows the hostname to be set
|
|
on unix systems if the calling process has sufficient privileges.
|
|
(Contributed by Ross Lagerwall in :issue:`10866`.)
|
|
|
|
|
|
socketserver
|
|
------------
|
|
|
|
:class:`~socketserver.BaseServer` now has an overridable method
|
|
:meth:`~socketserver.BaseServer.service_actions` that is called by the
|
|
:meth:`~socketserver.BaseServer.serve_forever` method in the service loop.
|
|
:class:`~socketserver.ForkingMixIn` now uses this to clean up zombie
|
|
child processes. (Contributed by Justin Warkentin in :issue:`11109`.)
|
|
|
|
|
|
sqlite3
|
|
-------
|
|
|
|
New :class:`sqlite3.Connection` method
|
|
:meth:`~sqlite3.Connection.set_trace_callback` can be used to capture a trace of
|
|
all sql commands processed by sqlite. (Contributed by Torsten Landschoff
|
|
in :issue:`11688`.)
|
|
|
|
|
|
ssl
|
|
---
|
|
|
|
* The :mod:`ssl` module has two new random generation functions:
|
|
|
|
* :func:`~ssl.RAND_bytes`: generate cryptographically strong
|
|
pseudo-random bytes.
|
|
* :func:`~ssl.RAND_pseudo_bytes`: generate pseudo-random bytes.
|
|
|
|
(Contributed by Victor Stinner in :issue:`12049`.)
|
|
|
|
* The :mod:`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 :issue:`11183`.)
|
|
|
|
* :meth:`~ssl.SSLContext.load_cert_chain` now accepts a *password* argument
|
|
to be used if the private key is encrypted.
|
|
(Contributed by Adam Simpkins in :issue:`12803`.)
|
|
|
|
* Diffie-Hellman key exchange, both regular and Elliptic Curve-based, is
|
|
now supported through the :meth:`~ssl.SSLContext.load_dh_params` and
|
|
:meth:`~ssl.SSLContext.set_ecdh_curve` methods.
|
|
(Contributed by Antoine Pitrou in :issue:`13626` and :issue:`13627`.)
|
|
|
|
* SSL sockets have a new :meth:`~ssl.SSLSocket.get_channel_binding` method
|
|
allowing the implementation of certain authentication mechanisms such as
|
|
SCRAM-SHA-1-PLUS. (Contributed by Jacek Konieczny in :issue:`12551`.)
|
|
|
|
* You can query the SSL compression algorithm used by an SSL socket, thanks
|
|
to its new :meth:`~ssl.SSLSocket.compression` method. The new attribute
|
|
:attr:`~ssl.OP_NO_COMPRESSION` can be used to disable compression.
|
|
(Contributed by Antoine Pitrou in :issue:`13634`.)
|
|
|
|
* Support has been added for the Next Protocol Negotiation extension using
|
|
the :meth:`ssl.SSLContext.set_npn_protocols` method.
|
|
(Contributed by Colin Marc in :issue:`14204`.)
|
|
|
|
* SSL errors can now be introspected more easily thanks to
|
|
:attr:`~ssl.SSLError.library` and :attr:`~ssl.SSLError.reason` attributes.
|
|
(Contributed by Antoine Pitrou in :issue:`14837`.)
|
|
|
|
* The :func:`~ssl.get_server_certificate` function now supports IPv6.
|
|
(Contributed by Charles-François Natali in :issue:`11811`.)
|
|
|
|
* New attribute :attr:`~ssl.OP_CIPHER_SERVER_PREFERENCE` allows setting
|
|
SSLv3 server sockets to use the server's cipher ordering preference rather
|
|
than the client's (:issue:`13635`).
|
|
|
|
|
|
stat
|
|
----
|
|
|
|
The undocumented tarfile.filemode function has been moved to
|
|
:func:`stat.filemode`. It can be used to convert a file's mode to a string of
|
|
the form '-rwxrwxrwx'.
|
|
|
|
(Contributed by Giampaolo Rodolà in :issue:`14807`.)
|
|
|
|
|
|
struct
|
|
------
|
|
|
|
The :mod:`struct` module now supports ``ssize_t`` and ``size_t`` via the
|
|
new codes ``n`` and ``N``, respectively. (Contributed by Antoine Pitrou
|
|
in :issue:`3163`.)
|
|
|
|
|
|
subprocess
|
|
----------
|
|
|
|
Command strings can now be bytes objects on posix platforms. (Contributed by
|
|
Victor Stinner in :issue:`8513`.)
|
|
|
|
A new constant :data:`~subprocess.DEVNULL` allows suppressing output in a
|
|
platform-independent fashion. (Contributed by Ross Lagerwall in
|
|
:issue:`5870`.)
|
|
|
|
|
|
sys
|
|
---
|
|
|
|
The :mod:`sys` module has a new :data:`~sys.thread_info` :term:`named
|
|
tuple` holding information about the thread implementation
|
|
(:issue:`11223`).
|
|
|
|
|
|
tarfile
|
|
-------
|
|
|
|
:mod:`tarfile` now supports ``lzma`` encoding via the :mod:`lzma` module.
|
|
(Contributed by Lars Gustäbel in :issue:`5689`.)
|
|
|
|
|
|
tempfile
|
|
--------
|
|
|
|
:class:`tempfile.SpooledTemporaryFile`\'s
|
|
:meth:`~tempfile.SpooledTemporaryFile.truncate` method now accepts
|
|
a ``size`` parameter. (Contributed by Ryan Kelly in :issue:`9957`.)
|
|
|
|
|
|
textwrap
|
|
--------
|
|
|
|
The :mod:`textwrap` module has a new :func:`~textwrap.indent` that makes
|
|
it straightforward to add a common prefix to selected lines in a block
|
|
of text (:issue:`13857`).
|
|
|
|
|
|
threading
|
|
---------
|
|
|
|
:class:`threading.Condition`, :class:`threading.Semaphore`,
|
|
:class:`threading.BoundedSemaphore`, :class:`threading.Event`, and
|
|
:class:`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 :issue:`10968`.)
|
|
|
|
The :class:`threading.Thread` constructor now accepts a ``daemon`` keyword
|
|
argument to override the default behavior of inheriting the ``daemon`` flag
|
|
value from the parent thread (:issue:`6064`).
|
|
|
|
The formerly private function ``_thread.get_ident`` is now available as the
|
|
public function :func:`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 :mod:`time` module:
|
|
|
|
* :func:`~time.get_clock_info`: Get information on a clock.
|
|
* :func:`~time.monotonic`: Monotonic clock (cannot go backward), not affected
|
|
by system clock updates.
|
|
* :func:`~time.perf_counter`: Performance counter with the highest available
|
|
resolution to measure a short duration.
|
|
* :func:`~time.process_time`: Sum of the system and user CPU time of the
|
|
current process.
|
|
|
|
Other new functions:
|
|
|
|
* :func:`~time.clock_getres`, :func:`~time.clock_gettime` and
|
|
:func:`~time.clock_settime` functions with ``CLOCK_xxx`` constants.
|
|
(Contributed by Victor Stinner in :issue:`10278`.)
|
|
|
|
To improve cross platform consistency, :func:`~time.sleep` now raises a
|
|
:exc:`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 :class:`types.MappingProxyType` class: Read-only proxy of a mapping.
|
|
(:issue:`14386`)
|
|
|
|
|
|
The new functions :func:`types.new_class` and :func:`types.prepare_class` provide support
|
|
for :pep:`3115` compliant dynamic type creation. (:issue:`14588`)
|
|
|
|
|
|
unittest
|
|
--------
|
|
|
|
:meth:`.assertRaises`, :meth:`.assertRaisesRegex`, :meth:`.assertWarns`, and
|
|
:meth:`.assertWarnsRegex` now accept a keyword argument *msg* when used as
|
|
context managers. (Contributed by Ezio Melotti and Winston Ewert in
|
|
:issue:`10775`.)
|
|
|
|
:meth:`unittest.TestCase.run` now returns the :class:`~unittest.TestResult`
|
|
object.
|
|
|
|
|
|
urllib
|
|
------
|
|
|
|
The :class:`~urllib.request.Request` class, now accepts a *method* argument
|
|
used by :meth:`~urllib.request.Request.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'))
|
|
|
|
(:issue:`1673007`)
|
|
|
|
|
|
webbrowser
|
|
----------
|
|
|
|
The :mod:`webbrowser` module supports more "browsers": Google Chrome (named
|
|
:program:`chrome`, :program:`chromium`, :program:`chrome-browser` or
|
|
:program:`chromium-browser` depending on the version and operating system),
|
|
and the generic launchers :program:`xdg-open`, from the FreeDesktop.org
|
|
project, and :program:`gvfs-open`, which is the default URI handler for GNOME
|
|
3. (The former contributed by Arnaud Calmettes in :issue:`13620`, the latter
|
|
by Matthias Klose in :issue:`14493`.)
|
|
|
|
|
|
xml.etree.ElementTree
|
|
---------------------
|
|
|
|
The :mod:`xml.etree.ElementTree` module now imports its C accelerator by
|
|
default; there is no longer a need to explicitly import
|
|
:mod:`xml.etree.cElementTree` (this module stays for backwards compatibility,
|
|
but is now deprecated). In addition, the ``iter`` family of methods of
|
|
:class:`~xml.etree.ElementTree.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 :attr:`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 :issue:`12646`.)
|
|
|
|
New attribute :attr:`zlib.ZLIB_RUNTIME_VERSION` reports the version string of
|
|
the underlying ``zlib`` library that is loaded at runtime. (Contributed by
|
|
Torsten Landschoff in :issue:`12306`.)
|
|
|
|
|
|
Optimizations
|
|
=============
|
|
|
|
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, :issue:`14624`, :issue:`14738` and
|
|
:issue:`15026`.)
|
|
|
|
|
|
Build and C API Changes
|
|
=======================
|
|
|
|
Changes to Python's build process and to the C API include:
|
|
|
|
* New :pep:`3118` related function:
|
|
|
|
* :c:func:`PyMemoryView_FromMemory`
|
|
|
|
* :pep:`393` added new Unicode types, macros and functions:
|
|
|
|
* High-level API:
|
|
|
|
* :c:func:`PyUnicode_CopyCharacters`
|
|
* :c:func:`PyUnicode_FindChar`
|
|
* :c:func:`PyUnicode_GetLength`, :c:macro:`PyUnicode_GET_LENGTH`
|
|
* :c:func:`PyUnicode_New`
|
|
* :c:func:`PyUnicode_Substring`
|
|
* :c:func:`PyUnicode_ReadChar`, :c:func:`PyUnicode_WriteChar`
|
|
|
|
* Low-level API:
|
|
|
|
* :c:type:`Py_UCS1`, :c:type:`Py_UCS2`, :c:type:`Py_UCS4` types
|
|
* :c:type:`PyASCIIObject` and :c:type:`PyCompactUnicodeObject` structures
|
|
* :c:macro:`PyUnicode_READY`
|
|
* :c:func:`PyUnicode_FromKindAndData`
|
|
* :c:func:`PyUnicode_AsUCS4`, :c:func:`PyUnicode_AsUCS4Copy`
|
|
* :c:macro:`PyUnicode_DATA`, :c:macro:`PyUnicode_1BYTE_DATA`,
|
|
:c:macro:`PyUnicode_2BYTE_DATA`, :c:macro:`PyUnicode_4BYTE_DATA`
|
|
* :c:macro:`PyUnicode_KIND` with :c:type:`PyUnicode_Kind` enum:
|
|
:c:data:`PyUnicode_WCHAR_KIND`, :c:data:`PyUnicode_1BYTE_KIND`,
|
|
:c:data:`PyUnicode_2BYTE_KIND`, :c:data:`PyUnicode_4BYTE_KIND`
|
|
* :c:macro:`PyUnicode_READ`, :c:macro:`PyUnicode_READ_CHAR`, :c:macro:`PyUnicode_WRITE`
|
|
* :c:macro:`PyUnicode_MAX_CHAR_VALUE`
|
|
|
|
* :c:macro:`PyArg_ParseTuple` now accepts a :class:`bytearray` for the ``c``
|
|
format (:issue:`12380`).
|
|
|
|
|
|
|
|
Deprecated
|
|
==========
|
|
|
|
Unsupported Operating Systems
|
|
-----------------------------
|
|
|
|
OS/2 and VMS are no longer supported due to the lack of a maintainer.
|
|
|
|
Windows 2000 and Windows platforms which set ``COMSPEC`` to ``command.com``
|
|
are no longer supported due to maintenance burden.
|
|
|
|
OSF support, which was deprecated in 3.2, has been completely removed.
|
|
|
|
|
|
Deprecated Python modules, functions and methods
|
|
------------------------------------------------
|
|
|
|
* Passing a non-empty string to ``object.__format__()`` is deprecated, and
|
|
will produce a :exc:`TypeError` in Python 3.4 (:issue:`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``)
|
|
* :meth:`ftplib.FTP.nlst` and :meth:`ftplib.FTP.dir`: use
|
|
:meth:`ftplib.FTP.mlsd`
|
|
* :func:`platform.popen`: use the :mod:`subprocess` module. Check especially
|
|
the :ref:`subprocess-replacements` section (:issue:`11377`).
|
|
* :issue:`13374`: The Windows bytes API has been deprecated in the :mod:`os`
|
|
module. Use Unicode filenames, instead of bytes filenames, to not depend on
|
|
the ANSI code page anymore and to support any filename.
|
|
* :issue:`13988`: The :mod:`xml.etree.cElementTree` module is deprecated. The
|
|
accelerator is used automatically whenever available.
|
|
* The behaviour of :func:`time.clock` depends on the platform: use the new
|
|
:func:`time.perf_counter` or :func:`time.process_time` function instead,
|
|
depending on your requirements, to have a well defined behaviour.
|
|
* The :func:`os.stat_float_times` function is deprecated.
|
|
* :mod:`abc` module:
|
|
|
|
* :class:`abc.abstractproperty` has been deprecated, use :class:`property`
|
|
with :func:`abc.abstractmethod` instead.
|
|
* :class:`abc.abstractclassmethod` has been deprecated, use
|
|
:class:`classmethod` with :func:`abc.abstractmethod` instead.
|
|
* :class:`abc.abstractstaticmethod` has been deprecated, use
|
|
:class:`staticmethod` with :func:`abc.abstractmethod` instead.
|
|
|
|
* :mod:`importlib` package:
|
|
|
|
* :meth:`importlib.abc.SourceLoader.path_mtime` is now deprecated in favour of
|
|
:meth:`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.
|
|
|
|
|
|
|
|
|
|
|
|
Deprecated functions and types of the C API
|
|
-------------------------------------------
|
|
|
|
The :c:type:`Py_UNICODE` has been deprecated by :pep:`393` and will be
|
|
removed in Python 4. All functions using this type are deprecated:
|
|
|
|
Unicode functions and methods using :c:type:`Py_UNICODE` and
|
|
:c:type:`Py_UNICODE*` types:
|
|
|
|
* :c:macro:`PyUnicode_FromUnicode`: use :c:func:`PyUnicode_FromWideChar` or
|
|
:c:func:`PyUnicode_FromKindAndData`
|
|
* :c:macro:`PyUnicode_AS_UNICODE`, :c:func:`PyUnicode_AsUnicode`,
|
|
:c:func:`PyUnicode_AsUnicodeAndSize`: use :c:func:`PyUnicode_AsWideCharString`
|
|
* :c:macro:`PyUnicode_AS_DATA`: use :c:macro:`PyUnicode_DATA` with
|
|
:c:macro:`PyUnicode_READ` and :c:macro:`PyUnicode_WRITE`
|
|
* :c:macro:`PyUnicode_GET_SIZE`, :c:func:`PyUnicode_GetSize`: use
|
|
:c:macro:`PyUnicode_GET_LENGTH` or :c:func:`PyUnicode_GetLength`
|
|
* :c:macro:`PyUnicode_GET_DATA_SIZE`: use
|
|
``PyUnicode_GET_LENGTH(str) * PyUnicode_KIND(str)`` (only work on ready
|
|
strings)
|
|
* :c:func:`PyUnicode_AsUnicodeCopy`: use :c:func:`PyUnicode_AsUCS4Copy` or
|
|
:c:func:`PyUnicode_AsWideCharString`
|
|
* :c:func:`PyUnicode_GetMax`
|
|
|
|
|
|
Functions and macros manipulating Py_UNICODE* strings:
|
|
|
|
* :c:macro:`Py_UNICODE_strlen`: use :c:func:`PyUnicode_GetLength` or
|
|
:c:macro:`PyUnicode_GET_LENGTH`
|
|
* :c:macro:`Py_UNICODE_strcat`: use :c:func:`PyUnicode_CopyCharacters` or
|
|
:c:func:`PyUnicode_FromFormat`
|
|
* :c:macro:`Py_UNICODE_strcpy`, :c:macro:`Py_UNICODE_strncpy`,
|
|
:c:macro:`Py_UNICODE_COPY`: use :c:func:`PyUnicode_CopyCharacters` or
|
|
:c:func:`PyUnicode_Substring`
|
|
* :c:macro:`Py_UNICODE_strcmp`: use :c:func:`PyUnicode_Compare`
|
|
* :c:macro:`Py_UNICODE_strncmp`: use :c:func:`PyUnicode_Tailmatch`
|
|
* :c:macro:`Py_UNICODE_strchr`, :c:macro:`Py_UNICODE_strrchr`: use
|
|
:c:func:`PyUnicode_FindChar`
|
|
* :c:macro:`Py_UNICODE_FILL`: use :c:func:`PyUnicode_Fill`
|
|
* :c:macro:`Py_UNICODE_MATCH`
|
|
|
|
Encoders:
|
|
|
|
* :c:func:`PyUnicode_Encode`: use :c:func:`PyUnicode_AsEncodedObject`
|
|
* :c:func:`PyUnicode_EncodeUTF7`
|
|
* :c:func:`PyUnicode_EncodeUTF8`: use :c:func:`PyUnicode_AsUTF8` or
|
|
:c:func:`PyUnicode_AsUTF8String`
|
|
* :c:func:`PyUnicode_EncodeUTF32`
|
|
* :c:func:`PyUnicode_EncodeUTF16`
|
|
* :c:func:`PyUnicode_EncodeUnicodeEscape` use
|
|
:c:func:`PyUnicode_AsUnicodeEscapeString`
|
|
* :c:func:`PyUnicode_EncodeRawUnicodeEscape` use
|
|
:c:func:`PyUnicode_AsRawUnicodeEscapeString`
|
|
* :c:func:`PyUnicode_EncodeLatin1`: use :c:func:`PyUnicode_AsLatin1String`
|
|
* :c:func:`PyUnicode_EncodeASCII`: use :c:func:`PyUnicode_AsASCIIString`
|
|
* :c:func:`PyUnicode_EncodeCharmap`
|
|
* :c:func:`PyUnicode_TranslateCharmap`
|
|
* :c:func:`PyUnicode_EncodeMBCS`: use :c:func:`PyUnicode_AsMBCSString` or
|
|
:c:func:`PyUnicode_EncodeCodePage` (with ``CP_ACP`` code_page)
|
|
* :c:func:`PyUnicode_EncodeDecimal`,
|
|
:c:func:`PyUnicode_TransformDecimalToASCII`
|
|
|
|
|
|
Deprecated features
|
|
-------------------
|
|
|
|
The :mod:`array` module's ``'u'`` format code is now deprecated and will be
|
|
removed in Python 4 together with the rest of the (:c:type:`Py_UNICODE`) API.
|
|
|
|
|
|
Porting to Python 3.3
|
|
=====================
|
|
|
|
This section lists previously described changes and other bugfixes
|
|
that may require changes to your code.
|
|
|
|
.. _portingpythoncode:
|
|
|
|
Porting Python code
|
|
-------------------
|
|
|
|
* Hash randomization is enabled by default. Set the :envvar:`PYTHONHASHSEED`
|
|
environment variable to ``0`` to disable hash randomization. See also the
|
|
:meth:`object.__hash__` method.
|
|
|
|
* :issue:`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.
|
|
|
|
* :issue:`13847`, :issue:`14180`: :mod:`time` and :mod:`datetime`:
|
|
:exc:`OverflowError` is now raised instead of :exc:`ValueError` if a
|
|
timestamp is out of range. :exc:`OSError` is now raised if C functions
|
|
:c:func:`gmtime` or :c:func:`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 :func:`importlib.invalidate_caches` to clear
|
|
out the cache for the finders to notice the new file.
|
|
|
|
* :exc:`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 :func:`__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
|
|
:func:`importlib.import_module` rather than call :func:`__import__` directly.
|
|
|
|
* :func:`__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 :attr:`sys.meta_path` and :attr:`sys.path_hooks` now have finders on
|
|
them by default, you will most likely want to use :meth:`list.insert` instead
|
|
of :meth:`list.append` to add to those lists.
|
|
|
|
* Because ``None`` is now inserted into :attr:`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**
|
|
:class:`imp.NullImporter` to be backwards-compatible. This will lead to extra
|
|
overhead on older versions of Python that re-insert ``None`` into
|
|
:attr:`sys.path_importer_cache` where it represents the use of implicit
|
|
finders, but semantically it should not change anything.
|
|
|
|
* :class:`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 :term:`path entry finders <path entry finder>`.
|
|
|
|
* :mod:`pkgutil` has been converted to use :mod:`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
|
|
:func:`pkgutil.iter_importers` and :func:`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 (:issue:`1079`) in the parsing done by
|
|
:func:`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.
|
|
|
|
* :func:`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 (:issue:`1690608`).
|
|
|
|
* :meth:`poplib.POP3.quit` may now raise protocol errors like all other
|
|
``poplib`` methods. Code that assumes ``quit`` does not raise
|
|
:exc:`poplib.error_proto` errors may need to be changed if errors on ``quit``
|
|
are encountered by a particular application (:issue:`11291`).
|
|
|
|
* The ``strict`` argument to :class:`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
|
|
:mod:`decimal` module. It was previously replaced by the public attribute
|
|
:attr:`~decimal.Context.clamp`. (See :issue:`8540`.)
|
|
|
|
* The undocumented internal helper class ``SSLFakeFile`` has been removed
|
|
from :mod:`smtplib`, since its functionality has long been provided directly
|
|
by :meth:`socket.socket.makefile`.
|
|
|
|
* Passing a negative value to :func:`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 :attr:`sys.version_info`
|
|
to make the decision.
|
|
|
|
* Code that used to work around the fact that the :mod:`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 (:issue:`13550`).
|
|
|
|
|
|
Porting C code
|
|
--------------
|
|
|
|
* In the course of changes to the buffer API the undocumented
|
|
:c:member:`~Py_buffer.smalltable` member of the
|
|
:c:type:`Py_buffer` structure has been removed and the
|
|
layout of the :c:type:`PyMemoryViewObject` has changed.
|
|
|
|
All extensions relying on the relevant parts in ``memoryobject.h``
|
|
or ``object.h`` must be rebuilt.
|
|
|
|
* Due to :ref:`PEP 393 <pep-393>`, the :c:type:`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 :doc:`Unicode API <../c-api/unicode>`.
|
|
|
|
However, if you only have been using high-level functions such as
|
|
:c:func:`PyUnicode_Concat()`, :c:func:`PyUnicode_Join` or
|
|
:c:func:`PyUnicode_FromFormat()`, your code will automatically take
|
|
advantage of the new unicode representations.
|
|
|
|
* :c:func:`PyImport_GetMagicNumber` now returns ``-1`` upon failure.
|
|
|
|
* As a negative value for the *level* argument to :func:`__import__` is no
|
|
longer valid, the same now holds for :c:func:`PyImport_ImportModuleLevel`.
|
|
This also means that the value of *level* used by
|
|
:c:func:`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 :issue:`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.
|
|
|
|
(:issue:`10998`, contributed by Éric Araujo.)
|
|
|
|
* When :program:`python` is started with :option:`-S`, ``import site``
|
|
will no longer add site-specific paths to the module search paths. In
|
|
previous versions, it did.
|
|
|
|
(:issue:`11591`, contributed by Carl Meyer with editions by Éric Araujo.)
|