python-docs-fr/howto/pyporting.po

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#: ../Doc/howto/pyporting.rst:5
msgid "Porting Python 2 Code to Python 3"
msgstr ""

#: ../Doc/howto/pyporting.rst:0
msgid "author"
msgstr "auteur"

#: ../Doc/howto/pyporting.rst:7
msgid "Brett Cannon"
msgstr ""

#: ../Doc/howto/pyporting.rst:None
msgid "Abstract"
msgstr "Résumé"

#: ../Doc/howto/pyporting.rst:11
msgid ""
"With Python 3 being the future of Python while Python 2 is still in active "
"use, it is good to have your project available for both major releases of "
"Python. This guide is meant to help you figure out how best to support both "
"Python 2 & 3 simultaneously."
msgstr ""

#: ../Doc/howto/pyporting.rst:16
msgid ""
"If you are looking to port an extension module instead of pure Python code, "
"please see :ref:`cporting-howto`."
msgstr ""

#: ../Doc/howto/pyporting.rst:19
msgid ""
"If you would like to read one core Python developer's take on why Python 3 "
"came into existence, you can read Nick Coghlan's `Python 3 Q & A`_ or Brett "
"Cannon's `Why Python 3 exists`_."
msgstr ""

#: ../Doc/howto/pyporting.rst:23
msgid ""
"For help with porting, you can email the python-porting_ mailing list with "
"questions."
msgstr ""

#: ../Doc/howto/pyporting.rst:27
msgid "The Short Explanation"
msgstr ""

#: ../Doc/howto/pyporting.rst:29
msgid ""
"To make your project be single-source Python 2/3 compatible, the basic steps "
"are:"
msgstr ""

#: ../Doc/howto/pyporting.rst:32
msgid "Only worry about supporting Python 2.7"
msgstr ""

#: ../Doc/howto/pyporting.rst:33
msgid ""
"Make sure you have good test coverage (coverage.py_ can help; ``pip install "
"coverage``)"
msgstr ""

#: ../Doc/howto/pyporting.rst:35 ../Doc/howto/pyporting.rst:116
msgid "Learn the differences between Python 2 & 3"
msgstr ""

#: ../Doc/howto/pyporting.rst:36
msgid ""
"Use Futurize_ (or Modernize_) to update your code (e.g. ``pip install "
"future``)"
msgstr ""

#: ../Doc/howto/pyporting.rst:37
msgid ""
"Use Pylint_ to help make sure you don't regress on your Python 3 support "
"(``pip install pylint``)"
msgstr ""

#: ../Doc/howto/pyporting.rst:39
msgid ""
"Use caniusepython3_ to find out which of your dependencies are blocking your "
"use of Python 3 (``pip install caniusepython3``)"
msgstr ""

#: ../Doc/howto/pyporting.rst:41
msgid ""
"Once your dependencies are no longer blocking you, use continuous "
"integration to make sure you stay compatible with Python 2 & 3 (tox_ can "
"help test against multiple versions of Python; ``pip install tox``)"
msgstr ""

#: ../Doc/howto/pyporting.rst:44
msgid ""
"Consider using optional static type checking to make sure your type usage "
"works in both Python 2 & 3 (e.g. use mypy_ to check your typing under both "
"Python 2 & Python 3)."
msgstr ""

#: ../Doc/howto/pyporting.rst:50
msgid "Details"
msgstr "Détails"

#: ../Doc/howto/pyporting.rst:52
msgid ""
"A key point about supporting Python 2 & 3 simultaneously is that you can "
"start **today**! Even if your dependencies are not supporting Python 3 yet "
"that does not mean you can't modernize your code **now** to support Python "
"3. Most changes required to support Python 3 lead to cleaner code using "
"newer practices even in Python 2 code."
msgstr ""

#: ../Doc/howto/pyporting.rst:58
msgid ""
"Another key point is that modernizing your Python 2 code to also support "
"Python 3 is largely automated for you. While you might have to make some API "
"decisions thanks to Python 3 clarifying text data versus binary data, the "
"lower-level work is now mostly done for you and thus can at least benefit "
"from the automated changes immediately."
msgstr ""

#: ../Doc/howto/pyporting.rst:64
msgid ""
"Keep those key points in mind while you read on about the details of porting "
"your code to support Python 2 & 3 simultaneously."
msgstr ""

#: ../Doc/howto/pyporting.rst:69
msgid "Drop support for Python 2.6 and older"
msgstr ""

#: ../Doc/howto/pyporting.rst:71
msgid ""
"While you can make Python 2.5 work with Python 3, it is **much** easier if "
"you only have to work with Python 2.7. If dropping Python 2.5 is not an "
"option then the six_ project can help you support Python 2.5 & 3 "
"simultaneously (``pip install six``). Do realize, though, that nearly all "
"the projects listed in this HOWTO will not be available to you."
msgstr ""

#: ../Doc/howto/pyporting.rst:77
msgid ""
"If you are able to skip Python 2.5 and older, then the required changes to "
"your code should continue to look and feel like idiomatic Python code. At "
"worst you will have to use a function instead of a method in some instances "
"or have to import a function instead of using a built-in one, but otherwise "
"the overall transformation should not feel foreign to you."
msgstr ""

#: ../Doc/howto/pyporting.rst:83
msgid ""
"But you should aim for only supporting Python 2.7. Python 2.6 is no longer "
"freely supported and thus is not receiving bugfixes. This means **you** will "
"have to work around any issues you come across with Python 2.6. There are "
"also some tools mentioned in this HOWTO which do not support Python 2.6 (e."
"g., Pylint_), and this will become more commonplace as time goes on. It will "
"simply be easier for you if you only support the versions of Python that you "
"have to support."
msgstr ""

#: ../Doc/howto/pyporting.rst:92
msgid ""
"Make sure you specify the proper version support in your ``setup.py`` file"
msgstr ""

#: ../Doc/howto/pyporting.rst:94
msgid ""
"In your ``setup.py`` file you should have the proper `trove classifier`_ "
"specifying what versions of Python you support. As your project does not "
"support Python 3 yet you should at least have ``Programming Language :: "
"Python :: 2 :: Only`` specified. Ideally you should also specify each major/"
"minor version of Python that you do support, e.g. ``Programming Language :: "
"Python :: 2.7``."
msgstr ""

#: ../Doc/howto/pyporting.rst:103
msgid "Have good test coverage"
msgstr ""

#: ../Doc/howto/pyporting.rst:105
msgid ""
"Once you have your code supporting the oldest version of Python 2 you want "
"it to, you will want to make sure your test suite has good coverage. A good "
"rule of thumb is that if you want to be confident enough in your test suite "
"that any failures that appear after having tools rewrite your code are "
"actual bugs in the tools and not in your code. If you want a number to aim "
"for, try to get over 80% coverage (and don't feel bad if you find it hard to "
"get better than 90% coverage). If you don't already have a tool to measure "
"test coverage then coverage.py_ is recommended."
msgstr ""

#: ../Doc/howto/pyporting.rst:118
msgid ""
"Once you have your code well-tested you are ready to begin porting your code "
"to Python 3! But to fully understand how your code is going to change and "
"what you want to look out for while you code, you will want to learn what "
"changes Python 3 makes in terms of Python 2. Typically the two best ways of "
"doing that is reading the `\"What's New\"`_ doc for each release of Python 3 "
"and the `Porting to Python 3`_ book (which is free online). There is also a "
"handy `cheat sheet`_ from the Python-Future project."
msgstr ""

#: ../Doc/howto/pyporting.rst:128
msgid "Update your code"
msgstr ""

#: ../Doc/howto/pyporting.rst:130
msgid ""
"Once you feel like you know what is different in Python 3 compared to Python "
"2, it's time to update your code! You have a choice between two tools in "
"porting your code automatically: Futurize_ and Modernize_. Which tool you "
"choose will depend on how much like Python 3 you want your code to be. "
"Futurize_ does its best to make Python 3 idioms and practices exist in "
"Python 2, e.g. backporting the ``bytes`` type from Python 3 so that you have "
"semantic parity between the major versions of Python. Modernize_, on the "
"other hand, is more conservative and targets a Python 2/3 subset of Python, "
"directly relying on six_ to help provide compatibility. As Python 3 is the "
"future, it might be best to consider Futurize to begin adjusting to any new "
"practices that Python 3 introduces which you are not accustomed to yet."
msgstr ""

#: ../Doc/howto/pyporting.rst:142
msgid ""
"Regardless of which tool you choose, they will update your code to run under "
"Python 3 while staying compatible with the version of Python 2 you started "
"with. Depending on how conservative you want to be, you may want to run the "
"tool over your test suite first and visually inspect the diff to make sure "
"the transformation is accurate. After you have transformed your test suite "
"and verified that all the tests still pass as expected, then you can "
"transform your application code knowing that any tests which fail is a "
"translation failure."
msgstr ""

#: ../Doc/howto/pyporting.rst:150
msgid ""
"Unfortunately the tools can't automate everything to make your code work "
"under Python 3 and so there are a handful of things you will need to update "
"manually to get full Python 3 support (which of these steps are necessary "
"vary between the tools). Read the documentation for the tool you choose to "
"use to see what it fixes by default and what it can do optionally to know "
"what will (not) be fixed for you and what you may have to fix on your own (e."
"g. using ``io.open()`` over the built-in ``open()`` function is off by "
"default in Modernize). Luckily, though, there are only a couple of things to "
"watch out for which can be considered large issues that may be hard to debug "
"if not watched for."
msgstr ""

#: ../Doc/howto/pyporting.rst:162
msgid "Division"
msgstr "Division"

#: ../Doc/howto/pyporting.rst:164
msgid ""
"In Python 3, ``5 / 2 == 2.5`` and not ``2``; all division between ``int`` "
"values result in a ``float``. This change has actually been planned since "
"Python 2.2 which was released in 2002. Since then users have been encouraged "
"to add ``from __future__ import division`` to any and all files which use "
"the ``/`` and ``//`` operators or to be running the interpreter with the ``-"
"Q`` flag. If you have not been doing this then you will need to go through "
"your code and do two things:"
msgstr ""

#: ../Doc/howto/pyporting.rst:172
msgid "Add ``from __future__ import division`` to your files"
msgstr ""

#: ../Doc/howto/pyporting.rst:173
msgid ""
"Update any division operator as necessary to either use ``//`` to use floor "
"division or continue using ``/`` and expect a float"
msgstr ""

#: ../Doc/howto/pyporting.rst:176
msgid ""
"The reason that ``/`` isn't simply translated to ``//`` automatically is "
"that if an object defines a ``__truediv__`` method but not ``__floordiv__`` "
"then your code would begin to fail (e.g. a user-defined class that uses ``/"
"`` to signify some operation but not ``//`` for the same thing or at all)."
msgstr ""

#: ../Doc/howto/pyporting.rst:183
msgid "Text versus binary data"
msgstr ""

#: ../Doc/howto/pyporting.rst:185
msgid ""
"In Python 2 you could use the ``str`` type for both text and binary data. "
"Unfortunately this confluence of two different concepts could lead to "
"brittle code which sometimes worked for either kind of data, sometimes not. "
"It also could lead to confusing APIs if people didn't explicitly state that "
"something that accepted ``str`` accepted either text or binary data instead "
"of one specific type. This complicated the situation especially for anyone "
"supporting multiple languages as APIs wouldn't bother explicitly supporting "
"``unicode`` when they claimed text data support."
msgstr ""

#: ../Doc/howto/pyporting.rst:194
msgid ""
"To make the distinction between text and binary data clearer and more "
"pronounced, Python 3 did what most languages created in the age of the "
"internet have done and made text and binary data distinct types that cannot "
"blindly be mixed together (Python predates widespread access to the "
"internet). For any code that deals only with text or only binary data, this "
"separation doesn't pose an issue. But for code that has to deal with both, "
"it does mean you might have to now care about when you are using text "
"compared to binary data, which is why this cannot be entirely automated."
msgstr ""

#: ../Doc/howto/pyporting.rst:203
msgid ""
"To start, you will need to decide which APIs take text and which take binary "
"(it is **highly** recommended you don't design APIs that can take both due "
"to the difficulty of keeping the code working; as stated earlier it is "
"difficult to do well). In Python 2 this means making sure the APIs that take "
"text can work with ``unicode`` and those that work with binary data work "
"with the ``bytes`` type from Python 3 (which is a subset of ``str`` in "
"Python 2 and acts as an alias for ``bytes`` type in Python 2). Usually the "
"biggest issue is realizing which methods exist on which types in Python 2 & "
"3 simultaneously (for text that's ``unicode`` in Python 2 and ``str`` in "
"Python 3, for binary that's ``str``/``bytes`` in Python 2 and ``bytes`` in "
"Python 3). The following table lists the **unique** methods of each data "
"type across Python 2 & 3 (e.g., the ``decode()`` method is usable on the "
"equivalent binary data type in either Python 2 or 3, but it can't be used by "
"the textual data type consistently between Python 2 and 3 because ``str`` in "
"Python 3 doesn't have the method). Do note that as of Python 3.5 the "
"``__mod__`` method was added to the bytes type."
msgstr ""

#: ../Doc/howto/pyporting.rst:220
msgid "**Text data**"
msgstr ""

#: ../Doc/howto/pyporting.rst:220
msgid "**Binary data**"
msgstr ""

#: ../Doc/howto/pyporting.rst:222
msgid "\\"
msgstr ""

#: ../Doc/howto/pyporting.rst:222
msgid "decode"
msgstr ""

#: ../Doc/howto/pyporting.rst:224
msgid "encode"
msgstr ""

#: ../Doc/howto/pyporting.rst:226
msgid "format"
msgstr ""

#: ../Doc/howto/pyporting.rst:228
msgid "isdecimal"
msgstr ""

#: ../Doc/howto/pyporting.rst:230
msgid "isnumeric"
msgstr ""

#: ../Doc/howto/pyporting.rst:233
msgid ""
"Making the distinction easier to handle can be accomplished by encoding and "
"decoding between binary data and text at the edge of your code. This means "
"that when you receive text in binary data, you should immediately decode it. "
"And if your code needs to send text as binary data then encode it as late as "
"possible. This allows your code to work with only text internally and thus "
"eliminates having to keep track of what type of data you are working with."
msgstr ""

#: ../Doc/howto/pyporting.rst:240
msgid ""
"The next issue is making sure you know whether the string literals in your "
"code represent text or binary data. You should add a ``b`` prefix to any "
"literal that presents binary data. For text you should add a ``u`` prefix to "
"the text literal. (there is a :mod:`__future__` import to force all "
"unspecified literals to be Unicode, but usage has shown it isn't as "
"effective as adding a ``b`` or ``u`` prefix to all literals explicitly)"
msgstr ""

#: ../Doc/howto/pyporting.rst:247
msgid ""
"As part of this dichotomy you also need to be careful about opening files. "
"Unless you have been working on Windows, there is a chance you have not "
"always bothered to add the ``b`` mode when opening a binary file (e.g., "
"``rb`` for binary reading).  Under Python 3, binary files and text files are "
"clearly distinct and mutually incompatible; see the :mod:`io` module for "
"details. Therefore, you **must** make a decision of whether a file will be "
"used for binary access (allowing binary data to be read and/or written) or "
"textual access (allowing text data to be read and/or written). You should "
"also use :func:`io.open` for opening files instead of the built-in :func:"
"`open` function as the :mod:`io` module is consistent from Python 2 to 3 "
"while the built-in :func:`open` function is not (in Python 3 it's actually :"
"func:`io.open`). Do not bother with the outdated practice of using :func:"
"`codecs.open` as that's only necessary for keeping compatibility with Python "
"2.5."
msgstr ""

#: ../Doc/howto/pyporting.rst:261
msgid ""
"The constructors of both ``str`` and ``bytes`` have different semantics for "
"the same arguments between Python 2 & 3. Passing an integer to ``bytes`` in "
"Python 2 will give you the string representation of the integer: ``bytes(3) "
"== '3'``. But in Python 3, an integer argument to ``bytes`` will give you a "
"bytes object as long as the integer specified, filled with null bytes: "
"``bytes(3) == b'\\x00\\x00\\x00'``. A similar worry is necessary when "
"passing a bytes object to ``str``. In Python 2 you just get the bytes object "
"back: ``str(b'3') == b'3'``. But in Python 3 you get the string "
"representation of the bytes object: ``str(b'3') == \"b'3'\"``."
msgstr ""

#: ../Doc/howto/pyporting.rst:271
msgid ""
"Finally, the indexing of binary data requires careful handling (slicing does "
"**not** require any special handling). In Python 2, ``b'123'[1] == b'2'`` "
"while in Python 3 ``b'123'[1] == 50``. Because binary data is simply a "
"collection of binary numbers, Python 3 returns the integer value for the "
"byte you index on. But in Python 2 because ``bytes == str``, indexing "
"returns a one-item slice of bytes. The six_ project has a function named "
"``six.indexbytes()`` which will return an integer like in Python 3: ``six."
"indexbytes(b'123', 1)``."
msgstr ""

#: ../Doc/howto/pyporting.rst:280
msgid "To summarize:"
msgstr ""

#: ../Doc/howto/pyporting.rst:282
msgid "Decide which of your APIs take text and which take binary data"
msgstr ""

#: ../Doc/howto/pyporting.rst:283
msgid ""
"Make sure that your code that works with text also works with ``unicode`` "
"and code for binary data works with ``bytes`` in Python 2 (see the table "
"above for what methods you cannot use for each type)"
msgstr ""

#: ../Doc/howto/pyporting.rst:286
msgid ""
"Mark all binary literals with a ``b`` prefix, textual literals with a ``u`` "
"prefix"
msgstr ""

#: ../Doc/howto/pyporting.rst:288
msgid ""
"Decode binary data to text as soon as possible, encode text as binary data "
"as late as possible"
msgstr ""

#: ../Doc/howto/pyporting.rst:290
msgid ""
"Open files using :func:`io.open` and make sure to specify the ``b`` mode "
"when appropriate"
msgstr ""

#: ../Doc/howto/pyporting.rst:292
msgid "Be careful when indexing into binary data"
msgstr ""

#: ../Doc/howto/pyporting.rst:296
msgid "Use feature detection instead of version detection"
msgstr ""

#: ../Doc/howto/pyporting.rst:298
msgid ""
"Inevitably you will have code that has to choose what to do based on what "
"version of Python is running. The best way to do this is with feature "
"detection of whether the version of Python you're running under supports "
"what you need. If for some reason that doesn't work then you should make the "
"version check be against Python 2 and not Python 3. To help explain this, "
"let's look at an example."
msgstr ""

#: ../Doc/howto/pyporting.rst:305
msgid ""
"Let's pretend that you need access to a feature of importlib_ that is "
"available in Python's standard library since Python 3.3 and available for "
"Python 2 through importlib2_ on PyPI. You might be tempted to write code to "
"access e.g. the ``importlib.abc`` module by doing the following::"
msgstr ""

#: ../Doc/howto/pyporting.rst:317
msgid ""
"The problem with this code is what happens when Python 4 comes out? It would "
"be better to treat Python 2 as the exceptional case instead of Python 3 and "
"assume that future Python versions will be more compatible with Python 3 "
"than Python 2::"
msgstr ""

#: ../Doc/howto/pyporting.rst:329
msgid ""
"The best solution, though, is to do no version detection at all and instead "
"rely on feature detection. That avoids any potential issues of getting the "
"version detection wrong and helps keep you future-compatible::"
msgstr ""

#: ../Doc/howto/pyporting.rst:340
msgid "Prevent compatibility regressions"
msgstr ""

#: ../Doc/howto/pyporting.rst:342
msgid ""
"Once you have fully translated your code to be compatible with Python 3, you "
"will want to make sure your code doesn't regress and stop working under "
"Python 3. This is especially true if you have a dependency which is blocking "
"you from actually running under Python 3 at the moment."
msgstr ""

#: ../Doc/howto/pyporting.rst:347
msgid ""
"To help with staying compatible, any new modules you create should have at "
"least the following block of code at the top of it::"
msgstr ""

#: ../Doc/howto/pyporting.rst:354
msgid ""
"You can also run Python 2 with the ``-3`` flag to be warned about various "
"compatibility issues your code triggers during execution. If you turn "
"warnings into errors with ``-Werror`` then you can make sure that you don't "
"accidentally miss a warning."
msgstr ""

#: ../Doc/howto/pyporting.rst:359
msgid ""
"You can also use the Pylint_ project and its ``--py3k`` flag to lint your "
"code to receive warnings when your code begins to deviate from Python 3 "
"compatibility. This also prevents you from having to run Modernize_ or "
"Futurize_ over your code regularly to catch compatibility regressions. This "
"does require you only support Python 2.7 and Python 3.4 or newer as that is "
"Pylint's minimum Python version support."
msgstr ""

#: ../Doc/howto/pyporting.rst:368
msgid "Check which dependencies block your transition"
msgstr ""

#: ../Doc/howto/pyporting.rst:370
msgid ""
"**After** you have made your code compatible with Python 3 you should begin "
"to care about whether your dependencies have also been ported. The "
"caniusepython3_ project was created to help you determine which projects -- "
"directly or indirectly -- are blocking you from supporting Python 3. There "
"is both a command-line tool as well as a web interface at https://"
"caniusepython3.com."
msgstr ""

#: ../Doc/howto/pyporting.rst:377
msgid ""
"The project also provides code which you can integrate into your test suite "
"so that you will have a failing test when you no longer have dependencies "
"blocking you from using Python 3. This allows you to avoid having to "
"manually check your dependencies and to be notified quickly when you can "
"start running on Python 3."
msgstr ""

#: ../Doc/howto/pyporting.rst:384
msgid "Update your ``setup.py`` file to denote Python 3 compatibility"
msgstr ""

#: ../Doc/howto/pyporting.rst:386
msgid ""
"Once your code works under Python 3, you should update the classifiers in "
"your ``setup.py`` to contain ``Programming Language :: Python :: 3`` and to "
"not specify sole Python 2 support. This will tell anyone using your code "
"that you support Python 2 **and** 3. Ideally you will also want to add "
"classifiers for each major/minor version of Python you now support."
msgstr ""

#: ../Doc/howto/pyporting.rst:394
msgid "Use continuous integration to stay compatible"
msgstr ""

#: ../Doc/howto/pyporting.rst:396
msgid ""
"Once you are able to fully run under Python 3 you will want to make sure "
"your code always works under both Python 2 & 3. Probably the best tool for "
"running your tests under multiple Python interpreters is tox_. You can then "
"integrate tox with your continuous integration system so that you never "
"accidentally break Python 2 or 3 support."
msgstr ""

#: ../Doc/howto/pyporting.rst:402
msgid ""
"You may also want to use the ``-bb`` flag with the Python 3 interpreter to "
"trigger an exception when you are comparing bytes to strings or bytes to an "
"int (the latter is available starting in Python 3.5). By default type-"
"differing comparisons simply return ``False``, but if you made a mistake in "
"your separation of text/binary data handling or indexing on bytes you "
"wouldn't easily find the mistake. This flag will raise an exception when "
"these kinds of comparisons occur, making the mistake much easier to track "
"down."
msgstr ""

#: ../Doc/howto/pyporting.rst:410
msgid ""
"And that's mostly it! At this point your code base is compatible with both "
"Python 2 and 3 simultaneously. Your testing will also be set up so that you "
"don't accidentally break Python 2 or 3 compatibility regardless of which "
"version you typically run your tests under while developing."
msgstr ""

#: ../Doc/howto/pyporting.rst:417
msgid "Consider using optional static type checking"
msgstr ""

#: ../Doc/howto/pyporting.rst:419
msgid ""
"Another way to help port your code is to use a static type checker like "
"mypy_ or pytype_ on your code. These tools can be used to analyze your code "
"as if it's being run under Python 2, then you can run the tool a second time "
"as if your code is running under Python 3. By running a static type checker "
"twice like this you can discover if you're e.g. misusing binary data type in "
"one version of Python compared to another. If you add optional type hints to "
"your code you can also explicitly state whether your APIs use textual or "
"binary data, helping to make sure everything functions as expected in both "
"versions of Python."
msgstr ""