Mailman 3 June 2016 - Python-Dev

Compact dict implementations (was: PEP 468
by INADA Naoki June 19, 2016

June 19, 2016

Hi, developers. I'm trying to implement compact dict. https://github.com/methane/cpython/pull/1 Current status is passing most of tests. Some tests are failing because of I haven't updated `sizeof` until layout fix. And I haven't dropped OrderedDict has linked list. Before finishing implementation, I want to see comments and tests from core developers. Please come to core-mentorship ML or pull request and try it if you interested in. Regards, -- INADA Naoki <songofacandy(a)gmail.com>

3 6

JUMP_ABSOLUTE in nested if statements
by Obiesie ike-nwosu June 19, 2016

June 19, 2016

Hi, Could some one give a hand with explaining to me why we have a JUMP_ABSOLUTE followed by a JUMP_FORWARD op code when this function is disassembled. >>> def f1(): ... a, b = 10, 11 ... if a >= 10: ... if b >= 11: ... print("hello world") … The disassembled function is shown below. >>> dis(f1) 2 0 LOAD_CONST 4 ((10, 11)) 3 UNPACK_SEQUENCE 2 6 STORE_FAST 0 (a) 9 STORE_FAST 1 (b) 3 12 LOAD_FAST 0 (a) 15 LOAD_CONST 1 (10) 18 COMPARE_OP 5 (>=) 21 POP_JUMP_IF_FALSE 47 4 24 LOAD_FAST 1 (b) 27 LOAD_CONST 2 (11) 30 COMPARE_OP 5 (>=) 33 POP_JUMP_IF_FALSE 47 5 36 LOAD_CONST 3 ('hello world') 39 PRINT_ITEM 40 PRINT_NEWLINE 41 JUMP_ABSOLUTE 47 44 JUMP_FORWARD 0 (to 47) >> 47 LOAD_CONST 0 (None) 50 RETURN_VALUE From my understanding, once JUMP_ABSOLUTE is executed, then JUMP_FORWARD is never gotten to so must be dead code so why is it being generated? Furthermore why is JUMP_ABSOLUTE rather than JUMP_FORWARD used in this particular case of nested if statements? I have tried other types of nested if statements and it has always been JUMP_FORWARD that is generated.

4 4

Summary of Python tracker Issues
by Python tracker June 17, 2016

June 17, 2016

ACTIVITY SUMMARY (2016-06-10 - 2016-06-17) 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 5544 ( -9) closed 33557 (+66) total 39101 (+57) Open issues with patches: 2417 Issues opened (41) ================== #10839: email module should not allow some header field repetitions http://bugs.python.org/issue10839 reopened by rhettinger #26171: heap overflow in zipimporter module http://bugs.python.org/issue26171 reopened by ned.deily #27288: secrets should use getrandom() on Linux http://bugs.python.org/issue27288 opened by dstufft #27292: Warn users that os.urandom() can return insecure values http://bugs.python.org/issue27292 opened by christian.heimes #27293: Summarize issues related to urandom, getrandom etc in secrets http://bugs.python.org/issue27293 opened by steven.daprano #27294: Better repr for Tkinter event objects http://bugs.python.org/issue27294 opened by serhiy.storchaka #27297: Add support for /dev/random to "secrets" http://bugs.python.org/issue27297 opened by larry #27298: redundant iteration over digits in _PyLong_AsUnsignedLongMask http://bugs.python.org/issue27298 opened by Oren Milman #27299: urllib does not splitport while putrequest realhost to HTTP he http://bugs.python.org/issue27299 opened by gr zhang #27300: tempfile.TemporaryFile(): missing errors=... argument http://bugs.python.org/issue27300 opened by mmarkk #27302: csv.Sniffer guesses wrong when unquoted fields contain quotes http://bugs.python.org/issue27302 opened by Redoute #27303: [argparse] Unify options in help output http://bugs.python.org/issue27303 opened by memeplex #27304: Create "Source Code" links in module sections, where relevant http://bugs.python.org/issue27304 opened by Yoni Lavi #27305: Crash with "pip list --outdated" on Windows 10 with Python 2.7 http://bugs.python.org/issue27305 opened by James.Paget #27307: string.Formatter does not support key/attribute access on unnu http://bugs.python.org/issue27307 opened by tbeadle #27309: Visual Styles support http://bugs.python.org/issue27309 opened by [HYBRID BEING] #27312: test_setupapp (idlelib.idle_test.test_macosx.SetupTest) fails http://bugs.python.org/issue27312 opened by ned.deily #27313: test case failures in test_widgets.ComboboxTest.of test_ttk_gu http://bugs.python.org/issue27313 opened by ned.deily #27314: Cannot install 3.5.2 with 3.6.0a1 installed http://bugs.python.org/issue27314 opened by steve.dower #27315: pydoc: prefer the pager command in favor of the specifc less c http://bugs.python.org/issue27315 opened by doko #27317: Handling data_files: too much is removed in uninstall http://bugs.python.org/issue27317 opened by sylvain.corlay #27318: Add support for symlinks to zipfile http://bugs.python.org/issue27318 opened by ldoktor #27319: Multiple item arguments for selection operations http://bugs.python.org/issue27319 opened by serhiy.storchaka #27320: ./setup.py --help-commands should sort extra commands http://bugs.python.org/issue27320 opened by Antony.Lee #27321: Email parser creates a message object that can't be flattened http://bugs.python.org/issue27321 opened by msapiro #27322: test_compile_path fails when python has been installed http://bugs.python.org/issue27322 opened by xdegaye #27323: ncurses putwin() fails in test_module_funcs http://bugs.python.org/issue27323 opened by xdegaye #27326: SIGSEV in test_window_funcs of test_curses http://bugs.python.org/issue27326 opened by xdegaye #27328: Documentation corrections for email defects http://bugs.python.org/issue27328 opened by martin.panter #27329: Document behavior when CDLL is called with None as an argumen http://bugs.python.org/issue27329 opened by Jeffrey Esquivel Sibaja #27331: Add a policy argument to email.mime.MIMEBase http://bugs.python.org/issue27331 opened by berker.peksag #27332: Clinic: first parameter for module-level functions should be P http://bugs.python.org/issue27332 opened by encukou #27333: validate_step in rangeobject.c, incorrect code logic but right http://bugs.python.org/issue27333 opened by xiang.zhang #27334: pysqlite3 context manager not performing rollback when a datab http://bugs.python.org/issue27334 opened by lciti #27335: Clarify that writing to locals() inside a class body is suppor http://bugs.python.org/issue27335 opened by steven.daprano #27337: 3.6.0a2 tarball has weird paths http://bugs.python.org/issue27337 opened by petere #27340: bytes-like objects with socket.sendall(), SSL, and http.client http://bugs.python.org/issue27340 opened by martin.panter #27341: mock.patch decorator fails silently on generators http://bugs.python.org/issue27341 opened by shoshber #27342: Clean up some Py_XDECREFs in rangeobject.c and bltinmodule.c http://bugs.python.org/issue27342 opened by xiang.zhang #27343: Incorrect error message for conflicting initializers of ctypes http://bugs.python.org/issue27343 opened by serhiy.storchaka #27344: zipfile *does* support utf-8 filenames http://bugs.python.org/issue27344 opened by dholth Most recent 15 issues with no replies (15) ========================================== #27344: zipfile *does* support utf-8 filenames http://bugs.python.org/issue27344 #27343: Incorrect error message for conflicting initializers of ctypes http://bugs.python.org/issue27343 #27341: mock.patch decorator fails silently on generators http://bugs.python.org/issue27341 #27340: bytes-like objects with socket.sendall(), SSL, and http.client http://bugs.python.org/issue27340 #27332: Clinic: first parameter for module-level functions should be P http://bugs.python.org/issue27332 #27331: Add a policy argument to email.mime.MIMEBase http://bugs.python.org/issue27331 #27329: Document behavior when CDLL is called with None as an argumen http://bugs.python.org/issue27329 #27328: Documentation corrections for email defects http://bugs.python.org/issue27328 #27326: SIGSEV in test_window_funcs of test_curses http://bugs.python.org/issue27326 #27323: ncurses putwin() fails in test_module_funcs http://bugs.python.org/issue27323 #27322: test_compile_path fails when python has been installed http://bugs.python.org/issue27322 #27317: Handling data_files: too much is removed in uninstall http://bugs.python.org/issue27317 #27309: Visual Styles support http://bugs.python.org/issue27309 #27307: string.Formatter does not support key/attribute access on unnu http://bugs.python.org/issue27307 #27304: Create "Source Code" links in module sections, where relevant http://bugs.python.org/issue27304 Most recent 15 issues waiting for review (15) ============================================= #27343: Incorrect error message for conflicting initializers of ctypes http://bugs.python.org/issue27343 #27342: Clean up some Py_XDECREFs in rangeobject.c and bltinmodule.c http://bugs.python.org/issue27342 #27334: pysqlite3 context manager not performing rollback when a datab http://bugs.python.org/issue27334 #27333: validate_step in rangeobject.c, incorrect code logic but right http://bugs.python.org/issue27333 #27332: Clinic: first parameter for module-level functions should be P http://bugs.python.org/issue27332 #27331: Add a policy argument to email.mime.MIMEBase http://bugs.python.org/issue27331 #27328: Documentation corrections for email defects http://bugs.python.org/issue27328 #27321: Email parser creates a message object that can't be flattened http://bugs.python.org/issue27321 #27320: ./setup.py --help-commands should sort extra commands http://bugs.python.org/issue27320 #27319: Multiple item arguments for selection operations http://bugs.python.org/issue27319 #27318: Add support for symlinks to zipfile http://bugs.python.org/issue27318 #27315: pydoc: prefer the pager command in favor of the specifc less c http://bugs.python.org/issue27315 #27307: string.Formatter does not support key/attribute access on unnu http://bugs.python.org/issue27307 #27304: Create "Source Code" links in module sections, where relevant http://bugs.python.org/issue27304 #27298: redundant iteration over digits in _PyLong_AsUnsignedLongMask http://bugs.python.org/issue27298 Top 10 most discussed issues (10) ================================= #27305: Crash with "pip list --outdated" on Windows 10 with Python 2.7 http://bugs.python.org/issue27305 18 msgs #27294: Better repr for Tkinter event objects http://bugs.python.org/issue27294 13 msgs #10839: email module should not allow some header field repetitions http://bugs.python.org/issue10839 12 msgs #25782: CPython hangs on error __context__ set to the error itself http://bugs.python.org/issue25782 12 msgs #27186: add os.fspath() http://bugs.python.org/issue27186 11 msgs #27292: Warn users that os.urandom() can return insecure values http://bugs.python.org/issue27292 11 msgs #27263: Tkinter sets the HOME environment variable, breaking scripts http://bugs.python.org/issue27263 9 msgs #25455: Some repr implementations don't check for self-referential str http://bugs.python.org/issue25455 8 msgs #27025: More human readable generated widget names http://bugs.python.org/issue27025 8 msgs #27288: secrets should use getrandom() on Linux http://bugs.python.org/issue27288 8 msgs Issues closed (62) ================== #5124: IDLE - pasting text doesn't delete selection http://bugs.python.org/issue5124 closed by terry.reedy #8637: Add MANPAGER envvar to specify pager for pydoc http://bugs.python.org/issue8637 closed by doko #14209: pkgutil.iter_zipimport_modules ignores the prefix parameter fo http://bugs.python.org/issue14209 closed by lukasz.langa #15468: Edit docs to hide hashlib.md5() http://bugs.python.org/issue15468 closed by gregory.p.smith #16182: readline: Wrong tab completion scope indices in Unicode termin http://bugs.python.org/issue16182 closed by martin.panter #16234: Implement correct block_size and tests for HMAC-SHA3 http://bugs.python.org/issue16234 closed by christian.heimes #16864: sqlite3.Cursor.lastrowid isn't populated when executing a SQL http://bugs.python.org/issue16864 closed by berker.peksag #17500: move PC/icons/source.xar to http://www.python.org/community/lo http://bugs.python.org/issue17500 closed by doko #19328: Improve PBKDF2 documentation http://bugs.python.org/issue19328 closed by christian.heimes #20508: IndexError from ipaddress._BaseNetwork.__getitem__ has no mess http://bugs.python.org/issue20508 closed by berker.peksag #20699: Document that binary IO classes work with bytes-likes objects http://bugs.python.org/issue20699 closed by martin.panter #20900: distutils register command should print text, not bytes repr http://bugs.python.org/issue20900 closed by berker.peksag #21386: ipaddress.IPv4Address.is_global not implemented http://bugs.python.org/issue21386 closed by berker.peksag #22558: Missing doc links to source code for Python-coded modules. http://bugs.python.org/issue22558 closed by terry.reedy #22970: asyncio: Cancelling wait() after notification leaves Condition http://bugs.python.org/issue22970 closed by yselivanov #24086: Configparser interpolation is unexpected http://bugs.python.org/issue24086 closed by lukasz.langa #24136: document PEP 448: unpacking generalization http://bugs.python.org/issue24136 closed by martin.panter #24750: IDLE: Cosmetic improvements for main window http://bugs.python.org/issue24750 closed by terry.reedy #24887: Sqlite3 has no option to provide open flags http://bugs.python.org/issue24887 closed by berker.peksag #25529: Provide access to the validated certificate chain in ssl modul http://bugs.python.org/issue25529 closed by berker.peksag #25724: SSLv3 test failure on Ubuntu 16.04 LTS http://bugs.python.org/issue25724 closed by martin.panter #26282: Add support for partial keyword arguments in extension functio http://bugs.python.org/issue26282 closed by serhiy.storchaka #26386: tkinter - Treeview - .selection_add and selection_toggle http://bugs.python.org/issue26386 closed by serhiy.storchaka #26556: Update expat to 2.2.1 http://bugs.python.org/issue26556 closed by python-dev #26862: android: SYS_getdents64 does not need to be defined on android http://bugs.python.org/issue26862 closed by xdegaye #27029: Remove support of deprecated mode 'U' in zipfile http://bugs.python.org/issue27029 closed by serhiy.storchaka #27030: Remove deprecated re features http://bugs.python.org/issue27030 closed by serhiy.storchaka #27095: Simplify MAKE_FUNCTION http://bugs.python.org/issue27095 closed by serhiy.storchaka #27122: Hang with contextlib.ExitStack and subprocess.Popen (regressio http://bugs.python.org/issue27122 closed by gregory.p.smith #27140: Opcode for creating dict with constant keys http://bugs.python.org/issue27140 closed by serhiy.storchaka #27188: sqlite3 execute* methods return value not documented http://bugs.python.org/issue27188 closed by berker.peksag #27190: Check sqlite3_version before allowing check_same_thread = Fals http://bugs.python.org/issue27190 closed by berker.peksag #27194: Tarfile superfluous truncate calls slows extraction. http://bugs.python.org/issue27194 closed by lukasz.langa #27221: multiprocessing documentation is outdated regarding method pic http://bugs.python.org/issue27221 closed by berker.peksag #27223: _read_ready and _write_ready should respect _conn_lost http://bugs.python.org/issue27223 closed by yselivanov #27227: argparse fails to parse [] when using choices and nargs='*' http://bugs.python.org/issue27227 closed by berker.peksag #27233: Missing documentation for PyOS_FSPath http://bugs.python.org/issue27233 closed by Jelle Zijlstra #27238: Bare except: usages in turtle.py http://bugs.python.org/issue27238 closed by serhiy.storchaka #27245: IDLE: Fix deletion of custom themes and key bindings http://bugs.python.org/issue27245 closed by terry.reedy #27262: IDLE: move Aqua context menu code to maxosx http://bugs.python.org/issue27262 closed by terry.reedy #27270: 'parentheses-equality' warnings when building with clang and c http://bugs.python.org/issue27270 closed by xdegaye #27272: random.Random should not read 2500 bytes from urandom http://bugs.python.org/issue27272 closed by rhettinger #27278: py_getrandom() uses an int for syscall() result http://bugs.python.org/issue27278 closed by haypo #27286: str object got multiple values for keyword argument http://bugs.python.org/issue27286 closed by serhiy.storchaka #27289: test_ftp_timeout fails with EOFError http://bugs.python.org/issue27289 closed by berker.peksag #27290: Turn heaps library into a more OOP data structure? http://bugs.python.org/issue27290 closed by rhettinger #27291: two heap corruption issues when running modified pyc code. http://bugs.python.org/issue27291 closed by gregory.p.smith #27295: heaps library does not have support for max heap http://bugs.python.org/issue27295 closed by rhettinger #27296: Urllib/Urlopen IncompleteRead with HTTP header with new line c http://bugs.python.org/issue27296 closed by martin.panter #27301: Incorrect return codes in compile.c http://bugs.python.org/issue27301 closed by serhiy.storchaka #27306: Grammatical Error in Documentation - Tarfile page http://bugs.python.org/issue27306 closed by berker.peksag #27308: Inconsistency in cgi.FieldStorage() causes unicode/byte TypeEr http://bugs.python.org/issue27308 closed by berker.peksag #27310: 3.6.0a2 IDLE.app on OS X fails to launch, use command line idl http://bugs.python.org/issue27310 closed by ned.deily #27311: Incorrect documentation for zipfile.writestr() http://bugs.python.org/issue27311 closed by martin.panter #27316: [PDB] NameError in list comprehension in PDB http://bugs.python.org/issue27316 closed by SilentGhost #27324: Error when building Python extension http://bugs.python.org/issue27324 closed by zach.ware #27325: random failure of test_builtin http://bugs.python.org/issue27325 closed by berker.peksag #27327: re documentation: typo "escapes consist of" http://bugs.python.org/issue27327 closed by ned.deily #27330: Possible leaks in ctypes http://bugs.python.org/issue27330 closed by serhiy.storchaka #27336: --without-threads build fails due to undeclared _PyGILState_ch http://bugs.python.org/issue27336 closed by berker.peksag #27338: python 2.7 platform.system reports wrong on Mac OS X El Capita http://bugs.python.org/issue27338 closed by Audric D'Hoest (Dr. Pariolo) #27339: Security Issue: Typosquatting http://bugs.python.org/issue27339 closed by haypo

1 0

Re: [Python-Dev] PEP 520: Ordered Class Definition Namespace
by Nikita Nemkin June 16, 2016

June 16, 2016

I'll reformulate my argument: Ordered class namespaces are a minority use case that's already covered by existing language features (custom metaclasses) and doesn't warrant the extension of the language (i.e. making OrderedDict a builtin type). This is about Python-the-Language, not CPython-the-runtime. If you disagree with this premise, there's no point arguing about the alternatives. That being said, below are the answers to your objections to specific alternatives. On Thu, Jun 16, 2016 at 1:30 AM, Nick Coghlan <ncoghlan(a)gmail.com> wrote: > On 14 June 2016 at 02:41, Nikita Nemkin <nikita(a)nemkin.ru> wrote: > > Adding metaclasses to an existing class can break compatibility with > third party subclasses, so making it possible for people to avoid that > while still gaining the ability to implicitly expose attribute > ordering to class decorators and other potentially interested parties > is a recurring theme behind this PEP and also PEPs 422 and 487. The simple answer is "don't do that", i.e. don't pile an ordered metaclass on top of another metaclass. Such use case is hypothetical anyway. Also, namespace argument to the default metaclass doesn't cause conflicts. >> 3. Making compiler fill in __definition_order__ for every class >> (just like __qualname__) without touching the runtime. >> ? > > Class scopes support conditionals and loops, so we can't necessarily > be sure what names will be assigned without running the code. It's > also possible to make attribute assignments via locals() that are > entirely opaque to the compiler, but visible to the interpreter at > runtime. All explicit assignments in the class body can be detected statically. Implicit assignments via locals(), sys._frame() etc. can't be detected, BUT they are unlikely to have a meaningful order! It's reasonable to exclude them from __definition_order__. This also applies to documentation tools. If there really was a need, they could have easily extracted static order, solving 99.9999% of the problem. > The rationale for "Why not make this configurable, rather than > switching it unilaterally?" is that it's actually *simpler* overall to > just make it the default - we can then change the documentation to say > "class bodies are evaluated in a collections.OrderedDict instance by > default" and record the consequences of that, rather than having to > document yet another class customisation mechanism. It would have been a "simpler" default if it was the core dict that became ordered. Instead, it brings in a 3rd party (OrderedDict). Documenting an extra metaclass or an extra type kward would hardly take more space. And it's NOT yet another mechanism. It's the good old metaclass mechanism. > It also eliminates boilerplate from class decorator usage > instructions, where people have to write "to use this class decorator, > you must also specify 'namespace=collections.OrderedDict' in your > class header" Statically inferred __definition_order__ would work here. Order-dependent decorators don't seem to be important enough to worry about their usability.

2 1

Why does base64 return bytes?
by Steven D'Aprano June 16, 2016

June 16, 2016

Normally I'd take a question like this to Python-List, but this question has turned out to be quite diversive, with people having strong opinions but no definitive answer. So I thought I'd ask here and hope that some of the core devs would have an idea. Why does base64 encoding in Python return bytes? base64.b64encode take bytes as input and returns bytes. Some people are arguing that this is wrong behaviour, as RFC 3548 specifies that Base64 should transform bytes to characters: https://tools.ietf.org/html/rfc3548.html albeit US-ASCII characters. E.g.: The encoding process represents 24-bit groups of input bits as output strings of 4 encoded characters. [...] Each 6-bit group is used as an index into an array of 64 printable characters. The character referenced by the index is placed in the output string. Are they misinterpreting the standard? Has Python got it wrong? Is there a good reason for returning bytes? I see that other languages choose different strategies. Microsoft's languages C#, F# and VB (plus their C++ compiler) take an array of bytes as input, and outputs a UTF-16 string: https://msdn.microsoft.com/en-us/library/dhx0d524%28v=vs.110%29.aspx Java's base64 encoder takes and returns bytes: https://docs.oracle.com/javase/8/docs/api/java/util/Base64.Encoder.html and Javascript's Base64 encoder takes input as UTF-16 encoded text and returns the same: https://developer.mozilla.org/en-US/docs/Web/API/WindowBase64/Base64_encodi… I'm not necessarily arguing that Python's strategy is the wrong one, but I am interested in what (if any) reasons are behind it. Thanks in advance, Steve

15 30

Smoothing the transition from Python 2 to 3
by Neil Schemenauer June 16, 2016

June 16, 2016

[I've posted something about this on python-ideas but since I now have some basic working code, I think it is more than an idea.] I think the uptake of Python 3 is starting to accelerate. That's good. However, there are still millions or maybe billions of lines of Python code that still needs to be ported. It is beneficial to the Python ecosystem if this code can get ported. My idea is to make a stepping stone version of Python, between 2.7.x and 3.x that eases the porting job. The high level goals are: - code coming out of 2to3 runs correctly on this modified Python - code that runs without warnings on this modified Python will run correctly on Python 3.x. Achieving these goals is not technically possible. Still, I want to reduce as much as possible the manual work involved in porting. Incrementally fixing code that generates warnings is a lot easier than trying to fix an entire application or library at once. I have a very early version on github: https://github.com/nascheme/ppython I'm hoping if people find it useful then they would contribute backwards compatibility fixes that help their applications or librarys run. I am currently running a newly 2to3 ported application on it. At this time there is no warning generated but I would rather get a warning then have one of my customers run into a porting bug. To be clear, I'm not proposing that these backwards compatiblity features go into Python 3.x or that this modified Python becomes the standard version. It is purely an intermediate step in getting code ported to Python 3. I've temporarily named it "Pragmatic Python". I'd like a better name if someone can suggest one. Maybe something like Perverted, Debauched or Impure Python. Regards, Neil

15 27

Re: [Python-Dev] BDFL ruling request: should we block forever waiting for high-quality random bits?
by Robert Collins June 16, 2016

June 16, 2016

On 16 Jun 2016 6:55 PM, "Larry Hastings" <larry(a)hastings.org> wrote: > > > Why do you call it only "semi-fixed"? As far as I understand it, the semantics of os.urandom() in 3.5.2rc1 are indistinguishable from reading from /dev/urandom directly, except it may not need to use a file handle. Which is a contract change. Someone testing in E.g. a chroot could have a different device on /dev/urandom, and now they will need to intercept syscalls for the same effect. Personally I think this is fine, but assuming i see Barry's point correctly, it is indeed but the same as it was. -rob

2 1

Re: [Python-Dev] Why does base64 return bytes?
by Steven D'Aprano June 16, 2016

June 16, 2016

On Tue, Jun 14, 2016 at 09:40:51PM -0700, Guido van Rossum wrote: > I'm officially on vacation, but I was surprised that people now assume > RFCs, which specify internet protocols, would have a bearing on programming > languages. (With perhaps an exception for RFCs that specifically specify > how programming languages or their libraries should treat certain specific > issues -- but I found no evidence that this RFC is doing that.) Sorry to disturb your vacation! I hoped that there might have been a nice simple answer, like "the main use-case for Base64 is the email module, which needs bytes, and thus it was decided". Or even "because backwards compatibility". Thanks to everyone for their constructive comments, and expecially Mark for digging up the original discussion on the Python-3000 list. I'm satisfied that the choice made by Python is the right choice, and that it meets the spirit (if, arguably, not the letter) of the RFC. -- Steve

5 5

Final round of the Python Language Summit coverage at LWN
by Jake Edge June 15, 2016

June 15, 2016

Hola python-dev, The final batch of articles from the Python Language Summit is now ready. The starting point is here: https://lwn.net/Articles/688969/ I have added the final six sessions (with SubscriberLinks for those without a subscription): Python 3 in Fedora: https://lwn.net/Articles/690676/ https://lwn.net/SubscriberLink/690676/cdf118081ac0ffd5/ The Python JITs are coming: https://lwn.net/Articles/691070/ https://lwn.net/SubscriberLink/691070/2714fd6a4934f016/ Pyjion: https://lwn.net/Articles/691152/ https://lwn.net/SubscriberLink/691152/6334fd8d5a9992c0/ Why is Python slow?: https://lwn.net/Articles/691243/ https://lwn.net/SubscriberLink/691243/669cb2bf2fe220c4/ Automated testing of CPython patches: https://lwn.net/Articles/691307/ https://lwn.net/SubscriberLink/691307/89feefecfe425f58/ The Python security response team: https://lwn.net/Articles/691308/ https://lwn.net/SubscriberLink/691308/432ff50e0f9b794f/ The articles will be freely available (without using the SubscriberLink) to the world at large in a week ... until then, feel free to share the SubscriberLinks. Hopefully I have captured things reasonably well. If there are corrections or clarifications needed, though, I recommend posting them as comments on the article. With luck, I will be able to sit in on the summit again next year ... enjoy! jake -- Jake Edge - LWN - jake(a)lwn.net - http://lwn.net

1 0

proposed os.fspath() change
by Ethan Furman June 15, 2016

June 15, 2016

I would like to make a change to os.fspath(). Specifically, os.fspath() currently raises an exception if something besides str, bytes, or os.PathLike is passed in, but makes no checks if an os.PathLike object returns something besides a str or bytes. I would like to change that to the opposite: if a non-os.PathLike is passed in, return it unchanged (so no change for str and bytes); if an os.PathLike object returns something that is not a str nor bytes, raise. An example of the difference in the lzma file: Current code (has not been upgraded to use os.fspath() yet) ----------------------------------------------------------- if isinstance(filename, (str, bytes)): if "b" not in mode: mode += "b" self._fp = builtins.open(filename, mode) self._closefp = True self._mode = mode_code elif hasattr(filename, "read") or hasattr(filename, "write"): self._fp = filename self._mode = mode_code else: raise TypeError( "filename must be a str or bytes object, or a file" ) Code change if using upgraded os.fspath() (placed before above stanza): filename = os.fspath(filename) Code change with current os.fspath() (ditto): if isinstance(filename, os.PathLike): filename = os.fspath(filename) My intention with the os.fspath() function was to minimize boiler-plate code and make PathLike objects easy and painless to support; having to discover if any given parameter is PathLike before calling os.fspath() on it is, IMHO, just the opposite. There is also precedent for having a __dunder__ check the return type: --> class Huh: ... def __int__(self): ... return 'string' ... def __index__(self): ... return b'bytestring' ... def __bool__(self): ... return 'true-ish' ... --> h = Huh() --> int(h) Traceback (most recent call last): File "<stdin>", line 1, in <module> TypeError: __int__ returned non-int (type str) --> ''[h] Traceback (most recent call last): File "<stdin>", line 1, in <module> TypeError: __index__ returned non-int (type bytes) --> bool(h) Traceback (most recent call last): File "<stdin>", line 1, in <module> TypeError: __bool__ should return bool, returned str Arguments in favor or against? -- ~Ethan~

5 16