Python-Dev July 2016

python-dev@python.org

57 participants
40 discussions

PEP 467: Minor API improvements to bytes, bytearray, and memoryview

by Ethan Furman

Minor changes: updated version numbers, add punctuation. The current text seems to take into account Guido's last comments. Thoughts before asking for acceptance? PEP: 467 Title: Minor API improvements for binary sequences Version: $Revision$ Last-Modified: $Date$ Author: Nick Coghlan <ncoghlan(a)gmail.com> Status: Draft Type: Standards Track Content-Type: text/x-rst Created: 2014-03-30 Python-Version: 3.5 Post-History: 2014-03-30 2014-08-15 2014-08-16 Abstract ======== During the initial development of the Python 3 language specification, the core ``bytes`` type for arbitrary binary data started as the mutable type that is now referred to as ``bytearray``. Other aspects of operating in the binary domain in Python have also evolved over the course of the Python 3 series. This PEP proposes four small adjustments to the APIs of the ``bytes``, ``bytearray`` and ``memoryview`` types to make it easier to operate entirely in the binary domain: * Deprecate passing single integer values to ``bytes`` and ``bytearray`` * Add ``bytes.zeros`` and ``bytearray.zeros`` alternative constructors * Add ``bytes.byte`` and ``bytearray.byte`` alternative constructors * Add ``bytes.iterbytes``, ``bytearray.iterbytes`` and ``memoryview.iterbytes`` alternative iterators Proposals ========= Deprecation of current "zero-initialised sequence" behaviour ------------------------------------------------------------ Currently, the ``bytes`` and ``bytearray`` constructors accept an integer argument and interpret it as meaning to create a zero-initialised sequence of the given size:: >>> bytes(3) b'\x00\x00\x00' >>> bytearray(3) bytearray(b'\x00\x00\x00') This PEP proposes to deprecate that behaviour in Python 3.6, and remove it entirely in Python 3.7. No other changes are proposed to the existing constructors. Addition of explicit "zero-initialised sequence" constructors ------------------------------------------------------------- To replace the deprecated behaviour, this PEP proposes the addition of an explicit ``zeros`` alternative constructor as a class method on both ``bytes`` and ``bytearray``:: >>> bytes.zeros(3) b'\x00\x00\x00' >>> bytearray.zeros(3) bytearray(b'\x00\x00\x00') It will behave just as the current constructors behave when passed a single integer. The specific choice of ``zeros`` as the alternative constructor name is taken from the corresponding initialisation function in NumPy (although, as these are 1-dimensional sequence types rather than N-dimensional matrices, the constructors take a length as input rather than a shape tuple). Addition of explicit "single byte" constructors ----------------------------------------------- As binary counterparts to the text ``chr`` function, this PEP proposes the addition of an explicit ``byte`` alternative constructor as a class method on both ``bytes`` and ``bytearray``:: >>> bytes.byte(3) b'\x03' >>> bytearray.byte(3) bytearray(b'\x03') These methods will only accept integers in the range 0 to 255 (inclusive):: >>> bytes.byte(512) Traceback (most recent call last): File "<stdin>", line 1, in <module> ValueError: bytes must be in range(0, 256) >>> bytes.byte(1.0) Traceback (most recent call last): File "<stdin>", line 1, in <module> TypeError: 'float' object cannot be interpreted as an integer The documentation of the ``ord`` builtin will be updated to explicitly note that ``bytes.byte`` is the inverse operation for binary data, while ``chr`` is the inverse operation for text data. Behaviourally, ``bytes.byte(x)`` will be equivalent to the current ``bytes([x])`` (and similarly for ``bytearray``). The new spelling is expected to be easier to discover and easier to read (especially when used in conjunction with indexing operations on binary sequence types). As a separate method, the new spelling will also work better with higher order functions like ``map``. Addition of optimised iterator methods that produce ``bytes`` objects --------------------------------------------------------------------- This PEP proposes that ``bytes``, ``bytearray`` and ``memoryview`` gain an optimised ``iterbytes`` method that produces length 1 ``bytes`` objects rather than integers:: for x in data.iterbytes(): # x is a length 1 ``bytes`` object, rather than an integer The method can be used with arbitrary buffer exporting objects by wrapping them in a ``memoryview`` instance first:: for x in memoryview(data).iterbytes(): # x is a length 1 ``bytes`` object, rather than an integer For ``memoryview``, the semantics of ``iterbytes()`` are defined such that:: memview.tobytes() == b''.join(memview.iterbytes()) This allows the raw bytes of the memory view to be iterated over without needing to make a copy, regardless of the defined shape and format. The main advantage this method offers over the ``map(bytes.byte, data)`` approach is that it is guaranteed *not* to fail midstream with a ``ValueError`` or ``TypeError``. By contrast, when using the ``map`` based approach, the type and value of the individual items in the iterable are only checked as they are retrieved and passed through the ``bytes.byte`` constructor. Design discussion ================= Why not rely on sequence repetition to create zero-initialised sequences? ------------------------------------------------------------------------- Zero-initialised sequences can be created via sequence repetition:: >>> b'\x00' * 3 b'\x00\x00\x00' >>> bytearray(b'\x00') * 3 bytearray(b'\x00\x00\x00') However, this was also the case when the ``bytearray`` type was originally designed, and the decision was made to add explicit support for it in the type constructor. The immutable ``bytes`` type then inherited that feature when it was introduced in PEP 3137. This PEP isn't revisiting that original design decision, just changing the spelling as users sometimes find the current behaviour of the binary sequence constructors surprising. In particular, there's a reasonable case to be made that ``bytes(x)`` (where ``x`` is an integer) should behave like the ``bytes.byte(x)`` proposal in this PEP. Providing both behaviours as separate class methods avoids that ambiguity. References ========== .. [1] Initial March 2014 discussion thread on python-ideas (https://mail.python.org/pipermail/python-ideas/2014-March/027295.html) .. [2] Guido's initial feedback in that thread (https://mail.python.org/pipermail/python-ideas/2014-March/027376.html) .. [3] Issue proposing moving zero-initialised sequences to a dedicated API (http://bugs.python.org/issue20895) .. [4] Issue proposing to use calloc() for zero-initialised binary sequences (http://bugs.python.org/issue21644) .. [5] August 2014 discussion thread on python-dev (https://mail.python.org/pipermail/python-ideas/2014-March/027295.html) Copyright ========= This document has been placed in the public domain.

4 years, 6 months

__qualname__ exposed as a local variable: standard?

by Carlos Pita

Hi all, I noticed __qualname__ is exposed by locals() while defining a class. This is handy but I'm not sure about its status: is it standard or just an artifact of the current implementation? (btw, the pycodestyle linter -former pep8- rejects its usage). I was unable to find any reference to this behavior in PEP 3155 nor in the language reference. Thank you in advance -- Carlos

4 years, 6 months

Status of Python 3.6 PEPs?

by Victor Stinner

Hi, I see many PEPs accepted for Python 3.6, or stil in draft status, but only a few final PEPs. What is happening? Reminder: the deadline for new features in Python 3.6 is 2016-09-12, only in 2 months and these 2 months are summer in the northern hemisphere which means holiday for many of them... Python 3.6 schedule and What's New in Python 3.6 list some PEPs: https://www.python.org/dev/peps/pep-0494/ https://docs.python.org/dev/whatsnew/3.6.html "PEP 499 -- python -m foo should bind sys.modules['foo'] in addition to sys.modules['__main__']" https://www.python.org/dev/peps/pep-0499/ => draft "PEP 498 -- Literal String Interpolation" https://www.python.org/dev/peps/pep-0498/ => accepted -- it's merged in Python 3.6, the status should be updated to Final no? "PEP 495 -- Local Time Disambiguation" https://www.python.org/dev/peps/pep-0495/ => accepted Alexander Belopolsky asked for a review of the implementation: https://mail.python.org/pipermail/python-dev/2016-June/145450.html "PEP 447 -- Add __getdescriptor__ method to metaclass" https://www.python.org/dev/peps/pep-0447/ => draft "PEP 487 -- Simpler customisation of class creation" https://www.python.org/dev/peps/pep-0487/ => draft "PEP 520 -- Preserving Class Attribute Definition Order" https://www.python.org/dev/peps/pep-0520/ => accepted -- what is the status of its implementation? "PEP 519 -- Adding a file system path protocol" https://www.python.org/dev/peps/pep-0519/ => accepted "PEP 467 -- Minor API improvements for binary sequences" https://www.python.org/dev/peps/pep-0467 => draft -- I saw recently some discussions around this PEP (on python-ideas?) It looks like os.fspath() exists, so the PEP is implemented. Its status should be Final, but the PEP should also be mentioned in What's New in Python 3.6 please. I also see some discussions for even more compact dict implementation. I wrote 3 PEPs, but I didn't have time recently to work of them (to make progress on the implementation of FAT Python): "PEP 509 -- Add a private version to dict" https://www.python.org/dev/peps/pep-0509/ => draft Pyjion, Cython, and Yury Selivanov are interested to use this feature, but last time I asked Guido, he didn't seem convinced by the advantages of the PEP. "PEP 510 -- Specialize functions with guards" https://www.python.org/dev/peps/pep-0510/ "PEP 511 -- API for code transformers" https://www.python.org/dev/peps/pep-0511/ These two PEPs are directly related to my FAT Python work. I was asked to prove that FAT Python makes CPython faster. Sadly, I failed to prove that. Moreover, it took me almost 2 months (and I'm not done yet!) to get stable benchmarks results on Python. I want to make sure that my changes don't make Python slower (don't introduce Python regressions), but the CPython benchmark is unstable, some benchmarks are very unstable. To get more information, follow the speed(a)python.org mailing list ;-) I probably forgot some PEPs, there are so many PEPs in the draft state :-( Victor

4 years, 6 months

Summary of Python tracker Issues

by Python tracker

ACTIVITY SUMMARY (2016-07-08 - 2016-07-15) Python tracker at http://bugs.python.org/ To view or respond to any of the issues listed below, click on the issue. Do NOT respond to this message. Issues counts and deltas: open 5562 (+12) closed 33715 (+39) total 39277 (+51) Open issues with patches: 2429 Issues opened (33) ================== #27469: Unicode filename gets crippled on Windows when drag and drop http://bugs.python.org/issue27469 reopened by eryksun #27470: -3 commandline option documented differently via man http://bugs.python.org/issue27470 opened by mgilson #27471: sre_constants.error: bad escape \d http://bugs.python.org/issue27471 opened by Noah Petherbridge #27472: add the 'unix_shell' attribute to test.support http://bugs.python.org/issue27472 opened by xdegaye #27477: IDLE: Switch dialogs to ttk widgets. http://bugs.python.org/issue27477 opened by terry.reedy #27482: heap-buffer-overflow on address 0x6250000078ff http://bugs.python.org/issue27482 opened by mtowalski #27483: Expose HEAD_LOCK/HEAD_UNLOCK in pystate.c http://bugs.python.org/issue27483 opened by fijall #27485: urllib.splitport -- is it official or not? http://bugs.python.org/issue27485 opened by gvanrossum #27486: FTPlib hangs on some pasv responses http://bugs.python.org/issue27486 opened by Byoungwoo Song #27487: -m switch regression in Python 3.5.2 (under rare circumstances http://bugs.python.org/issue27487 opened by wolma #27490: ARM cross-compile: pgen built without $(CFLAGS) as $(LIBRARY) http://bugs.python.org/issue27490 opened by Thomas Perl #27491: Errors when building with UNICODE character set http://bugs.python.org/issue27491 opened by Minmin.Gong #27492: Enhance bytearray_repr with bytes_repr's logic http://bugs.python.org/issue27492 opened by xiang.zhang #27493: logging module fails with unclear error when supplied a (Posix http://bugs.python.org/issue27493 opened by rhendrikse #27494: 2to3 parser failure caused by a comma after a generator expres http://bugs.python.org/issue27494 opened by jstasiak #27495: Pretty printing sorting for set and frozenset instances http://bugs.python.org/issue27495 opened by danilo.bellini #27496: unicodedata.name() doesn't have names for control characters http://bugs.python.org/issue27496 opened by zwol #27497: csv module: Add return value to DictWriter.writeheader http://bugs.python.org/issue27497 opened by lsowen #27499: PY_SSIZE_T_CLEAN conflicts with Py_LIMITED_API http://bugs.python.org/issue27499 opened by dholth #27500: ProactorEventLoop cannot open connection to ::1 http://bugs.python.org/issue27500 opened by sebastien.bourdeauducq #27501: Add typing.py class describing a PEP 3118 buffer object http://bugs.python.org/issue27501 opened by Daniel Moisset #27502: Python -m Module Vulnerable to Buffer Over Flow. http://bugs.python.org/issue27502 opened by DhirajMishra #27505: Missing documentation for setting module __class__ attribute http://bugs.python.org/issue27505 opened by ncoghlan #27506: make bytes/bytearray delete a keyword argument http://bugs.python.org/issue27506 opened by xiang.zhang #27507: bytearray.extend lacks overflow check when increasing buffer http://bugs.python.org/issue27507 opened by xiang.zhang #27509: Some tests breaks PGO build on Windows http://bugs.python.org/issue27509 opened by Charles G. #27511: Add PathLike objects support to BZ2File http://bugs.python.org/issue27511 opened by xiang.zhang #27512: os.fspath is certain to crash when exception raised in __fspat http://bugs.python.org/issue27512 opened by xiang.zhang #27513: email.utils.getaddresses does not handle Header objects http://bugs.python.org/issue27513 opened by frispete #27515: Dotted name re-import does not rebind after deletion http://bugs.python.org/issue27515 opened by terry.reedy #27516: Wrong initialization of python path with embeddable distributi http://bugs.python.org/issue27516 opened by palm.kevin #27517: LZMACompressor and LZMADecompressor raise exceptions if given http://bugs.python.org/issue27517 opened by benfogle #27520: Issue when building PGO http://bugs.python.org/issue27520 opened by Decorater Most recent 15 issues with no replies (15) ========================================== #27520: Issue when building PGO http://bugs.python.org/issue27520 #27511: Add PathLike objects support to BZ2File http://bugs.python.org/issue27511 #27505: Missing documentation for setting module __class__ attribute http://bugs.python.org/issue27505 #27494: 2to3 parser failure caused by a comma after a generator expres http://bugs.python.org/issue27494 #27491: Errors when building with UNICODE character set http://bugs.python.org/issue27491 #27486: FTPlib hangs on some pasv responses http://bugs.python.org/issue27486 #27482: heap-buffer-overflow on address 0x6250000078ff http://bugs.python.org/issue27482 #27470: -3 commandline option documented differently via man http://bugs.python.org/issue27470 #27451: gzip.py: Please save more of the gzip header for later examina http://bugs.python.org/issue27451 #27446: struct: allow per-item byte order http://bugs.python.org/issue27446 #27445: Charset instance not passed to set_payload() http://bugs.python.org/issue27445 #27435: ctypes and AIX - also for 2.7.X (and later) http://bugs.python.org/issue27435 #27428: Document WindowsRegistryFinder inherits from MetaPathFinder http://bugs.python.org/issue27428 #27426: Encoding mismatch causes some tests to fail on Windows http://bugs.python.org/issue27426 #27420: Docs for os.link - say what happens if link already exists http://bugs.python.org/issue27420 Most recent 15 issues waiting for review (15) ============================================= #27517: LZMACompressor and LZMADecompressor raise exceptions if given http://bugs.python.org/issue27517 #27512: os.fspath is certain to crash when exception raised in __fspat http://bugs.python.org/issue27512 #27511: Add PathLike objects support to BZ2File http://bugs.python.org/issue27511 #27507: bytearray.extend lacks overflow check when increasing buffer http://bugs.python.org/issue27507 #27506: make bytes/bytearray delete a keyword argument http://bugs.python.org/issue27506 #27501: Add typing.py class describing a PEP 3118 buffer object http://bugs.python.org/issue27501 #27495: Pretty printing sorting for set and frozenset instances http://bugs.python.org/issue27495 #27492: Enhance bytearray_repr with bytes_repr's logic http://bugs.python.org/issue27492 #27491: Errors when building with UNICODE character set http://bugs.python.org/issue27491 #27477: IDLE: Switch dialogs to ttk widgets. http://bugs.python.org/issue27477 #27472: add the 'unix_shell' attribute to test.support http://bugs.python.org/issue27472 #27461: Optimize PNGs http://bugs.python.org/issue27461 #27454: PyUnicode_InternInPlace can use PyDict_SetDefault http://bugs.python.org/issue27454 #27453: $CPP invocation in configure must use $CPPFLAGS http://bugs.python.org/issue27453 #27452: IDLE: Cleanup config code http://bugs.python.org/issue27452 Top 10 most discussed issues (10) ================================= #26988: Add AutoNumberedEnum to stdlib http://bugs.python.org/issue26988 19 msgs #27078: Make f'' strings faster than .format: BUILD_STRING opcode? http://bugs.python.org/issue27078 15 msgs #27487: -m switch regression in Python 3.5.2 (under rare circumstances http://bugs.python.org/issue27487 15 msgs #27512: os.fspath is certain to crash when exception raised in __fspat http://bugs.python.org/issue27512 14 msgs #14977: mailcap does not respect precedence in the presence of wildcar http://bugs.python.org/issue14977 13 msgs #18966: Threads within multiprocessing Process terminate early http://bugs.python.org/issue18966 13 msgs #27392: Add a server_side keyword parameter to create_connection http://bugs.python.org/issue27392 12 msgs #27515: Dotted name re-import does not rebind after deletion http://bugs.python.org/issue27515 12 msgs #27469: Unicode filename gets crippled on Windows when drag and drop http://bugs.python.org/issue27469 11 msgs #27497: csv module: Add return value to DictWriter.writeheader http://bugs.python.org/issue27497 10 msgs Issues closed (37) ================== #8538: Add FlagAction to argparse http://bugs.python.org/issue8538 closed by haypo #10697: host and port attributes not documented well in function urlli http://bugs.python.org/issue10697 closed by martin.panter #20674: Update comments in dictobject.c http://bugs.python.org/issue20674 closed by r.david.murray #22125: Cure signedness warnings introduced by #22003 http://bugs.python.org/issue22125 closed by berker.peksag #25548: Show the address in the repr for class objects http://bugs.python.org/issue25548 closed by python-dev #25572: _ssl doesn't build on OSX 10.11 http://bugs.python.org/issue25572 closed by matrixise #26176: EmailMessage example doesn't work http://bugs.python.org/issue26176 closed by r.david.murray #26446: Mention in the devguide that core dev stuff falls under the PS http://bugs.python.org/issue26446 closed by berker.peksag #26896: mix-up with the terms 'importer', 'finder', 'loader' in the im http://bugs.python.org/issue26896 closed by brett.cannon #26972: mistakes in docstrings in the import machinery http://bugs.python.org/issue26972 closed by brett.cannon #27027: add the 'is_android' attribute to test.support http://bugs.python.org/issue27027 closed by xdegaye #27180: Doc/pathlib: Please describe the behaviour of Path().rename() http://bugs.python.org/issue27180 closed by berker.peksag #27285: Document the deprecation of pyvenv in favor of `python3 -m ven http://bugs.python.org/issue27285 closed by brett.cannon #27369: Tests break with --with-system-expat and Expat 2.2.0 http://bugs.python.org/issue27369 closed by benjamin.peterson #27442: expose the Android API level in sysconfig.get_config_vars() http://bugs.python.org/issue27442 closed by xdegaye #27455: Fix tkinter examples to be PEP8 compliant http://bugs.python.org/issue27455 closed by berker.peksag #27466: [Copy from github user macartur] time2netscape missing comma http://bugs.python.org/issue27466 closed by orsenthil #27468: Erroneous memory behaviour for objects created in another thre http://bugs.python.org/issue27468 closed by Adria Garriga #27473: bytes_concat seems to check overflow using undefined behaviour http://bugs.python.org/issue27473 closed by serhiy.storchaka #27474: Unify exception in _Py_bytes_contains for integers http://bugs.python.org/issue27474 closed by serhiy.storchaka #27475: define_macros uses incorrect parameter for msvc compilers http://bugs.python.org/issue27475 closed by eryksun #27476: Introduce a .github folder with PULL_REQUEST_TEMPLATE http://bugs.python.org/issue27476 closed by berker.peksag #27478: Python Can't run http://bugs.python.org/issue27478 closed by orsenthil #27479: Slicing strings out of bounds does not raise IndexError http://bugs.python.org/issue27479 closed by eryksun #27480: Cannot link _crypt and _nis modules on a host with glibc-2.12 http://bugs.python.org/issue27480 closed by r.david.murray #27481: Replace TypeError with ValueError in doc regarding "embedded N http://bugs.python.org/issue27481 closed by serhiy.storchaka #27484: Some Examples in Format String Syntax are incorrect or poorly http://bugs.python.org/issue27484 closed by r.david.murray #27488: Underscore not showing Mac El Capitan http://bugs.python.org/issue27488 closed by zach.ware #27489: Win 10, choco install python gets message: Access to the path http://bugs.python.org/issue27489 closed by eryksun #27498: Regression in repr() of class object http://bugs.python.org/issue27498 closed by python-dev #27503: support RUSAGE_THREAD as a constant in the resource module http://bugs.python.org/issue27503 closed by r.david.murray #27504: Missing assertion methods in unittest documentation http://bugs.python.org/issue27504 closed by berker.peksag #27508: process thread with implicit join is killed unexpectedly http://bugs.python.org/issue27508 closed by tim.peters #27510: Found some Solution build missconfigurations. http://bugs.python.org/issue27510 closed by steve.dower #27514: SystemError when compiling deeply nested for loops http://bugs.python.org/issue27514 closed by python-dev #27518: small typo error in Grammar/Grammar http://bugs.python.org/issue27518 closed by berker.peksag #27519: update the references to http://mercurial.selenic.com http://bugs.python.org/issue27519 closed by berker.peksag

4 years, 6 months

PyPI index deprecation

by Dmitry Trofimov

Hi, as you probably already know, today the PyPI index page ( https://pypi.python.org/pypi?%3Aaction=index) was deprecated and ceased to be. Among other things it affected PyCharm IDE that relied on that page to enable packaging related features from the IDE. As a result users of PyCharm can no longer install/update PyPI packages from PyCharm. Here is an issue about that in our tracker: https://youtrack.jetbrains.com/issue/PY-20081 Given that there are several hundred thouthands of PyCharm users in the world -- all 3 editions: Professional, Community, and Educational are affected -- this can lead to a storm of a negative feedback, when people will start to face the denial of the service. The deprecation of the index was totally unexpected for us and we weren't prepared for that. Maybe we missed some announcement. We will be very happy if the functionality of the index is restored at least for some short period of time: please, give as a couple of weeks. That will allow us to implement a workaround and provide the fix for the several latest major versions of PyChram. Does anybody know who is responsible for that decision and whom to connect about it? Please help. Best regards, Dmitry Trofimov PyCharm Team Lead JetBrainshttp://www.jetbrains.com The Drive To Develop

4 years, 6 months

Should PY_SSIZE_T_CLEAN break Py_LIMITED_API?

by Daniel Holth

I was using Py_LIMITED_API under 3.5 and PY_SSIZE_T_CLEAN was set, this causes some functions not in the limited api to be used and the resulting extension segfaults in Linux. Is that right? Thanks, Daniel

4 years, 6 months

Proposal: explicitly disallow function/class mismatches in accelerator modules

by Nick Coghlan

I'm in the process of trying to disentangle http://bugs.python.org/issue27137 which points out some of the behavioural differences that arise when falling back from the original C implementation of functools.partial to the pure Python emulation that uses a closure. That issue was opened due to a few things that work with the C implementation that fail with the Python implementation: - the C version can be pickled (and hence used with multiprocessing) - the C version can be subclassed - the C version can be used in "isinstance" checks - the C version behaves as a static method, the Python version as a normal instance method While I'm planning to accept the patch that converts the pure Python version to a full class that matches the semantics of the C version in these areas as well as in its core behaviour, that last case is one where the pure Python version merely exhibits different behaviour from the C version, rather than failing outright. Given that the issues that arose in this case weren't at all obvious up front, what do folks think of the idea of updating PEP 399 to explicitly prohibit class/function mismatches between accelerator modules and their pure Python counterparts? The rationale for making such a change is that when it comes to true drop-in API compatibility, we have reasonable evidence that "they're both callables" isn't sufficient once the complexities of real world applications enter the picture. Regards, Nick. -- Nick Coghlan | ncoghlan(a)gmail.com | Brisbane, Australia

4 years, 6 months

[RELEASE] Python 3.6.0a3 is now available

by Ned Deily

On behalf of the Python development community and the Python 3.6 release team, I'm happy to announce the availability of Python 3.6.0a3. 3.6.0a3 is the third of four planned alpha releases of Python 3.6, the next major release of Python. During the alpha phase, Python 3.6 remains under heavy development: additional features will be added and existing features may be modified or deleted. Please keep in mind that this is a preview release and its use is not recommended for production environments. You can find Python 3.6.0a3 here: https://www.python.org/downloads/release/python-360a3/ The next release of Python 3.6 will be 3.6.0a4, currently scheduled for 2016-08-15. --Ned -- Ned Deily nad(a)python.org -- []

4 years, 6 months

Re: [Python-Dev] [Python-checkins] devguide: Star self as idlelib expert. Mark other 2 as inactive.

by Martin Panter

On 12 July 2016 at 03:47, terry.reedy <python-checkins(a)python.org> wrote: > https://hg.python.org/devguide/rev/cc1c0dd798e7 Terry it looks like you accidentally added Christian back (undoing <https://hg.python.org/devguide/rev/cc1c0dd798e7>) > -xml.parsers.expat > -xml.sax > +xml.parsers.expat christian.heimes > +xml.sax christian.heimes > xml.sax.handler > xml.sax.saxutils > xml.sax.xmlreader > @@ -319,7 +319,7 @@ > bytecode benjamin.peterson, pitrou, georg.brandl, yselivanov > context managers ncoghlan > coverity scan christian.heimes, brett.cannon, twouters > -cryptography gregory.p.smith, dstufft > +cryptography christian.heimes, gregory.p.smith, dstufft > data formats mark.dickinson, georg.brandl > database lemburg > devguide ncoghlan, eric.araujo, ezio.melotti, willingc > @@ -341,7 +341,7 @@ > georg.brandl > str.format eric.smith > testing michael.foord, pitrou, ezio.melotti > -test coverage giampaolo.rodola > +test coverage giampaolo.rodola, christian.heimes > threads pitrou > time and dates lemburg, belopolsky > unicode lemburg, ezio.melotti, haypo, benjamin.peterson, pitrou

4 years, 6 months

Python CFG Basic blocks

by Obiesie ike-nwosu

Hi, I am looking into how the python compiler generates basic blocks during the CFG generation process and my expectations from CFG theory seems to be at odds with how the python compiler actually generates its CFG. Take the following code snippet for example: def median(pool): copy = sorted(pool) size = len(copy) if size % 2 == 1: return copy[(size - 1) / 2] else: return (copy[size/2 - 1] + copy[size/2]) / 2 From my understanding of basic blocks in compilers, the above code snippet should have at least 3 basic blocks as follows: 1. Block 1 - all instructions up to and including those for the if test. 2. Block 2 - all instructions for the if body i.e the first return statement. 3. Block 3 - instructions for the else block i.e. the second return statement. My understanding of the the section on Control flow Graphs in the “Design of the CPython Compiler” also alludes to this - >> As an example, consider an ‘if’ statement with an ‘else’ block. The guard on the ‘if’ is a basic block which is pointed to by the basic block containing the code leading to the ‘if’ statement. The ‘if’ statement block contains jumps (which are exit points) to the true body of the ‘if’ and the ‘else’ body (which may be NULL), each of which are their own basic blocks. Both of those blocks in turn point to the basic block representing the code following the entire ‘if’ statement. The CPython compiler however seems to generate 2 basic blocks for the above snippets - 1. Block 1 - all instructions up to and including the if statement and the body of the if statement (the first return statement in this case) 2. Block 2 - instructions for the else block (the second return statement) Is there any reason for this or have I somehow missed something in the CFG generation process? Regards, Obi

4 years, 6 months

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2001

2000

1999

Python-Dev July 2016