Mailman 3 May 2015 - Python-Dev

Re: [Python-Dev] cpython (merge 3.4 -> default): Added tests for more builtin types.
by Ned Deily 18 May '15

18 May '15

In article <20150516183940.21146.77232(a)psf.io>, serhiy.storchaka <python-checkins(a)python.org> wrote: > https://hg.python.org/cpython/rev/7b350f712c0e > changeset: 96099:7b350f712c0e > parent: 96096:f0c94892ac31 > parent: 96098:955dffec3d94 > user: Serhiy Storchaka <storchaka(a)gmail.com> > date: Sat May 16 21:35:56 2015 +0300 > summary: > Added tests for more builtin types. > Made test_pprint discoverable. > > files: > Lib/test/test_pprint.py | 17 ++++++++--------- > 1 files changed, 8 insertions(+), 9 deletions(-) ====================================================================== ERROR: test_coverage (test.test_trace.TestCoverage) ---------------------------------------------------------------------- Traceback (most recent call last): File "/py/dev/3x/root/uxd/lib/python3.5/test/test_trace.py", line 312, in test_coverage self._coverage(tracer) File "/py/dev/3x/root/uxd/lib/python3.5/test/test_trace.py", line 305, in _coverage tracer.run(cmd) File "/py/dev/3x/root/uxd/lib/python3.5/trace.py", line 500, in run self.runctx(cmd, dict, dict) File "/py/dev/3x/root/uxd/lib/python3.5/trace.py", line 508, in runctx exec(cmd, globals, locals) File "<string>", line 1, in <module> AttributeError: module 'test.test_pprint' has no attribute 'test_main' ====================================================================== ERROR: test_coverage_ignore (test.test_trace.TestCoverage) ---------------------------------------------------------------------- Traceback (most recent call last): File "/py/dev/3x/root/uxd/lib/python3.5/test/test_trace.py", line 327, in test_coverage_ignore self._coverage(tracer) File "/py/dev/3x/root/uxd/lib/python3.5/test/test_trace.py", line 305, in _coverage tracer.run(cmd) File "/py/dev/3x/root/uxd/lib/python3.5/trace.py", line 500, in run self.runctx(cmd, dict, dict) File "/py/dev/3x/root/uxd/lib/python3.5/trace.py", line 508, in runctx exec(cmd, globals, locals) File "<string>", line 1, in <module> AttributeError: module 'test.test_pprint' has no attribute 'test_main' Also breaks 3.4. -- Ned Deily, nad(a)acm.org

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Re: [Python-Dev] [Python-checkins] peps: Apply Chris's changes, including an acceptance mark
by Yury Selivanov 17 May '15

17 May '15

Chris, Could you please add a link to the email where the PEP was accepted? Thanks, Yury On 2015-05-16 10:12 PM, chris.angelico wrote: > https://hg.python.org/peps/rev/f876276ce076 > changeset: 5854:f876276ce076 > user: Chris Angelico <rosuav(a)gmail.com> > date: Sun May 17 12:12:19 2015 +1000 > summary: > Apply Chris's changes, including an acceptance mark > > files: > pep-0485.txt | 6 +++--- > 1 files changed, 3 insertions(+), 3 deletions(-) > > > diff --git a/pep-0485.txt b/pep-0485.txt > --- a/pep-0485.txt > +++ b/pep-0485.txt > @@ -3,7 +3,7 @@ > Version: $Revision$ > Last-Modified: $Date$ > Author: Christopher Barker <Chris.Barker(a)noaa.gov> > -Status: Draft > +Status: Accepted > Type: Standards Track > Content-Type: text/x-rst > Created: 20-Jan-2015 > @@ -391,9 +391,9 @@ > The most common use case is expected to be small tolerances -- on order of the > default 1e-9. However there may be use cases where a user wants to know if two > fairly disparate values are within a particular range of each other: "is a > -within 200% (rel_tol = 2.0) of b? In this case, the string test would never > +within 200% (rel_tol = 2.0) of b? In this case, the strong test would never > indicate that two values are within that range of each other if one of them is > -zero. The strong case, however would use the larger (non-zero) value for the > +zero. The weak case, however would use the larger (non-zero) value for the > test, and thus return true if one value is zero. For example: is 0 within 200% > of 10? 200% of ten is 20, so the range within 200% of ten is -10 to +30. Zero > falls within that range, so it will return True. > > > > _______________________________________________ > Python-checkins mailing list > Python-checkins(a)python.org > https://mail.python.org/mailman/listinfo/python-checkins

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No tags in semi-official github mirror of cpython repository.
by INADA Naoki 16 May '15

16 May '15

Hi. I foud "semi official github mirror" of cpython. https://github.com/python/cpython I want to use it as upstream of our project (Translating docs in Japanese). But it doesn't have tags. Is the repository stable enough for forking project like us? Or should we use mercurial? Could you mirror tags too? Thanks -- INADA Naoki <songofacandy(a)gmail.com>

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Scandir module's C code updated to Python 3.5 code
by Ben Hoyt 16 May '15

16 May '15

Hi folks, With os.scandir() now in the Python 3.5 stdlib, I just thought I'd let folks know that I've released the scandir module version 1.0. So this is now basically a copy-n-paste of the C code that went into CPython 3.5's posixmodule.c with the necessary changes to make it work or Python 2.x (2.6+). You can use the following import to pick os.scandir/os.walk if on Python 3.5+ or the scandir module version otherwise: try: from os import scandir, walk except ImportError: from scandir import scandir, walk I've tested it and it all looks good and performs well, but please let me know if you have any issues! * PyPI: https://pypi.python.org/pypi/scandir * Github project: https://github.com/benhoyt/scandir Would love to hear any success/speedup stories, too! -Ben

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Minimal async event loop and async utilities (Was: PEP 492: async/await in Python; version 4)
by Paul Moore 16 May '15

16 May '15

On 6 May 2015 at 07:46, Greg Ewing <greg.ewing(a)canterbury.ac.nz> wrote: > Another problem with the "core" idea is that > you can't start with an event loop that "just does > scheduling" and then add on other features such > as I/O *from the outside*. There has to be some > point at which everything comes together, which > means choosing something like select() or > poll() or I/O completion queues, and build that > into the heart of your event loop. At that point > it's no longer something with a simple core. Looking at asyncio.queues, the only features it needs are: 1. asyncio.events.get_event_loop() 2. asyncio.futures.Future - creating a standalone Future 3. asyncio.locks.Event 4. @coroutine locks.Event in turn only needs the other 3 items. And you can ignore get_event_loop() as it's only used to get the default loop, you can pass in your own. And asyncio.futures only uses get_event_loop (and _format_callback) from asyncio.events. Futures require the loop to support: 1. call_soon 2. call_exception_handler 3. get_debug So, to some extent (how far is something I'd need to code up a loop to confirm) you can build the Futures and synchronisation mechanisms with an event loop that supports only this "minimal interface". Essentially, that's my goal - to allow people who want to write (say) a Windows GUI event loop, or a Windows event loop based of WaitForXXXObject, or a Tkinter loop, or whatever, to *not* have to write their own implementation of synchronisation or future objects. That may mean lifting the asyncio code and putting it into a separate library, to make the separation between "asyncio-dependent" and "general async" clearer. Or if asyncio's provisional status doesn't last long enough to do that, we may end up with an asyncio implementation and a separate (possibly 3rd party) "general" implementation. Paul.

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Re: [Python-Dev] cpython: inspect: Add __slots__ to BoundArguments.
by Serhiy Storchaka 16 May '15

16 May '15

On 14.05.15 00:38, yury.selivanov wrote: > https://hg.python.org/cpython/rev/ee31277386cb > changeset: 96038:ee31277386cb > user: Yury Selivanov <yselivanov(a)sprymix.com> > date: Wed May 13 17:18:41 2015 -0400 > summary: > inspect: Add __slots__ to BoundArguments. Note that adding __slots__ breaks pickleability.

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Summary of Python tracker Issues
by Python tracker 16 May '15

16 May '15

ACTIVITY SUMMARY (2015-05-08 - 2015-05-15) 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 4840 ( +2) closed 31123 (+54) total 35963 (+56) Open issues with patches: 2237 Issues opened (39) ================== #21162: code in multiprocessing.pool freeze if inside some code from s http://bugs.python.org/issue21162 reopened by Ivan.K #21593: Clarify re.search documentation first match http://bugs.python.org/issue21593 reopened by Joshua.Landau #23757: tuple function gives wrong answer when called on list subclass http://bugs.python.org/issue23757 reopened by r.david.murray #24134: assertRaises can behave differently http://bugs.python.org/issue24134 reopened by serhiy.storchaka #24147: doublequote are not well recognized with Dialect class http://bugs.python.org/issue24147 opened by MiK #24148: 'cum' not a valid sort key for pstats.Stats.sort_stats http://bugs.python.org/issue24148 opened by ramiro #24151: test_pydoc fails http://bugs.python.org/issue24151 opened by hsiehr #24152: test_mailcap fails if a mailcap file contains a non-decodable http://bugs.python.org/issue24152 opened by petrosr2 #24153: threading/multiprocessing tests fail on chromebook under crout http://bugs.python.org/issue24153 opened by shiprex #24154: pathlib.Path.rename moves file to Path.cwd() when argument is http://bugs.python.org/issue24154 opened by yurit #24157: test_urandom_fd_reopened failure if OS X crash reporter defaul http://bugs.python.org/issue24157 opened by skip.montanaro #24159: Misleading TypeError when pickling bytes to a file opened as t http://bugs.python.org/issue24159 opened by jason.coombs #24160: Pdb sometimes crashes when trying to remove a breakpoint defin http://bugs.python.org/issue24160 opened by ppperry #24162: [2.7 regression] test_asynchat test failure on i586-linux-gnu http://bugs.python.org/issue24162 opened by doko #24163: shutil.copystat fails when attribute security.selinux is prese http://bugs.python.org/issue24163 opened by sstirlin #24164: Support pickling objects with __new__ with keyword arguments w http://bugs.python.org/issue24164 opened by serhiy.storchaka #24165: Free list for single-digits ints http://bugs.python.org/issue24165 opened by serhiy.storchaka #24166: ArgumentParser behavior does not match generated help http://bugs.python.org/issue24166 opened by tellendil #24168: Unittest discover fails with namespace package if the path con http://bugs.python.org/issue24168 opened by toshishige hagihara #24169: sockets convert out-of-range port numbers % 2**16 http://bugs.python.org/issue24169 opened by Kurt.Rose #24172: Errors in resource.getpagesize module documentation http://bugs.python.org/issue24172 opened by mahmoud #24173: curses HOWTO/implementation disagreement http://bugs.python.org/issue24173 opened by White_Rabbit #24174: Python crash on exit http://bugs.python.org/issue24174 opened by gnumdk #24175: Test failure in test_utime on FreeBSD http://bugs.python.org/issue24175 opened by koobs #24176: Incorrect parsing of unpacked expressions in call http://bugs.python.org/issue24176 opened by tcaswell #24177: Add https?_proxy support to http.client http://bugs.python.org/issue24177 opened by demian.brecht #24180: PEP 492: Documentation http://bugs.python.org/issue24180 opened by yselivanov #24181: test_fileio crash, 3.5, Win 7 http://bugs.python.org/issue24181 opened by terry.reedy #24182: test_tcl assertion failure, 2.7, Win 7 http://bugs.python.org/issue24182 opened by terry.reedy #24186: OpenSSL causes buffer overrun exception http://bugs.python.org/issue24186 opened by steve.dower #24190: BoundArguments facility to inject defaults http://bugs.python.org/issue24190 opened by pitrou #24192: unexpected system error with pep420 style namespace packages http://bugs.python.org/issue24192 opened by ronaldoussoren #24193: Make LOGGING_FORMAT of assertLogs configurable http://bugs.python.org/issue24193 opened by berker.peksag #24194: tokenize yield an ERRORTOKEN if an identifier uses Other_ID_St http://bugs.python.org/issue24194 opened by Joshua.Landau #24195: Add `Executor.filter` to concurrent.futures http://bugs.python.org/issue24195 opened by cool-RR #24198: please align the platform tag for windows http://bugs.python.org/issue24198 opened by doko #24199: Idle: remove idlelib.idlever.py and its use in About dialog http://bugs.python.org/issue24199 opened by terry.reedy #24200: Redundant id in informative reprs http://bugs.python.org/issue24200 opened by serhiy.storchaka #24201: _winreg PyHKEY Type Confusion http://bugs.python.org/issue24201 opened by JohnLeitch Most recent 15 issues with no replies (15) ========================================== #24200: Redundant id in informative reprs http://bugs.python.org/issue24200 #24194: tokenize yield an ERRORTOKEN if an identifier uses Other_ID_St http://bugs.python.org/issue24194 #24193: Make LOGGING_FORMAT of assertLogs configurable http://bugs.python.org/issue24193 #24180: PEP 492: Documentation http://bugs.python.org/issue24180 #24177: Add https?_proxy support to http.client http://bugs.python.org/issue24177 #24176: Incorrect parsing of unpacked expressions in call http://bugs.python.org/issue24176 #24174: Python crash on exit http://bugs.python.org/issue24174 #24173: curses HOWTO/implementation disagreement http://bugs.python.org/issue24173 #24164: Support pickling objects with __new__ with keyword arguments w http://bugs.python.org/issue24164 #24162: [2.7 regression] test_asynchat test failure on i586-linux-gnu http://bugs.python.org/issue24162 #24159: Misleading TypeError when pickling bytes to a file opened as t http://bugs.python.org/issue24159 #24154: pathlib.Path.rename moves file to Path.cwd() when argument is http://bugs.python.org/issue24154 #24148: 'cum' not a valid sort key for pstats.Stats.sort_stats http://bugs.python.org/issue24148 #24143: Makefile in tarball don't provide make uninstall target http://bugs.python.org/issue24143 #24137: Force not using _default_root in IDLE http://bugs.python.org/issue24137 Most recent 15 issues waiting for review (15) ============================================= #24198: please align the platform tag for windows http://bugs.python.org/issue24198 #24195: Add `Executor.filter` to concurrent.futures http://bugs.python.org/issue24195 #24190: BoundArguments facility to inject defaults http://bugs.python.org/issue24190 #24176: Incorrect parsing of unpacked expressions in call http://bugs.python.org/issue24176 #24165: Free list for single-digits ints http://bugs.python.org/issue24165 #24164: Support pickling objects with __new__ with keyword arguments w http://bugs.python.org/issue24164 #24145: Support |= for parameters in converters http://bugs.python.org/issue24145 #24142: ConfigParser._read doesn't join multi-line values collected wh http://bugs.python.org/issue24142 #24136: document PEP 448 http://bugs.python.org/issue24136 #24134: assertRaises can behave differently http://bugs.python.org/issue24134 #24130: Remove -fno-common compile option from OS X framework builds? http://bugs.python.org/issue24130 #24129: Incorrect (misleading) statement in the execution model docume http://bugs.python.org/issue24129 #24117: Wrong range checking in GB18030 decoder. http://bugs.python.org/issue24117 #24114: ctypes.utils uninitialized variable 'path' http://bugs.python.org/issue24114 #24109: Documentation for difflib uses optparse http://bugs.python.org/issue24109 Top 10 most discussed issues (10) ================================= #24181: test_fileio crash, 3.5, Win 7 http://bugs.python.org/issue24181 10 msgs #23699: Add a macro to ease writing rich comparisons http://bugs.python.org/issue23699 9 msgs #23970: Update distutils.msvccompiler for VC14 http://bugs.python.org/issue23970 9 msgs #24195: Add `Executor.filter` to concurrent.futures http://bugs.python.org/issue24195 8 msgs #23971: dict(list) and dict.fromkeys() doesn't account for 2/3 fill ra http://bugs.python.org/issue23971 7 msgs #24165: Free list for single-digits ints http://bugs.python.org/issue24165 7 msgs #24190: BoundArguments facility to inject defaults http://bugs.python.org/issue24190 7 msgs #23857: Make default HTTPS certificate verification setting configurab http://bugs.python.org/issue23857 6 msgs #24182: test_tcl assertion failure, 2.7, Win 7 http://bugs.python.org/issue24182 6 msgs #24198: please align the platform tag for windows http://bugs.python.org/issue24198 6 msgs Issues closed (52) ================== #1322: Deprecate platform.dist() and platform.linux_distribution() fu http://bugs.python.org/issue1322 closed by berker.peksag #9514: platform.linux_distribution() under Ubuntu returns ('debian', http://bugs.python.org/issue9514 closed by lemburg #12018: No tests for ntpath.samefile, ntpath.sameopenfile http://bugs.python.org/issue12018 closed by r.david.murray #17762: platform.linux_distribution() should honor /etc/os-release http://bugs.python.org/issue17762 closed by lemburg #19934: collections.Counter.most_common does not document `None` as ac http://bugs.python.org/issue19934 closed by rhettinger #20172: Derby #3: Convert 67 sites to Argument Clinic across 4 files ( http://bugs.python.org/issue20172 closed by zach.ware #21795: smtpd.SMTPServer should announce 8BITMIME when supported and a http://bugs.python.org/issue21795 closed by r.david.murray #22064: Misleading message from 2to3 when skipping optional fixers http://bugs.python.org/issue22064 closed by berker.peksag #22486: Add math.gcd() http://bugs.python.org/issue22486 closed by benjamin.peterson #22547: Implement an informative `BoundArguments.__repr__` http://bugs.python.org/issue22547 closed by yselivanov #22681: Add support of KOI8-T encoding http://bugs.python.org/issue22681 closed by serhiy.storchaka #22682: Add support of KZ1048 (RK1048) encoding http://bugs.python.org/issue22682 closed by serhiy.storchaka #22906: PEP 479: Change StopIteration handling inside generators http://bugs.python.org/issue22906 closed by yselivanov #23042: ctypes module doesn't build on FreeBSD, RHEL (x86) - Undefined http://bugs.python.org/issue23042 closed by benjamin.peterson #23088: Document that PyUnicode_AsUTF8() returns a null-terminated str http://bugs.python.org/issue23088 closed by r.david.murray #23201: Decimal(0)**0 is an error, 0**0 is 1, but Decimal(0) == 0 http://bugs.python.org/issue23201 closed by rhettinger #23227: Generator's finally block not run if close() called before fir http://bugs.python.org/issue23227 closed by vadmium #23290: Faster set copying http://bugs.python.org/issue23290 closed by rhettinger #23488: Random objects twice as big as necessary on 64-bit builds http://bugs.python.org/issue23488 closed by serhiy.storchaka #23695: idiom for clustering a data series into n-length groups http://bugs.python.org/issue23695 closed by rhettinger #23796: BufferedReader.peek() crashes if closed http://bugs.python.org/issue23796 closed by berker.peksag #23870: pprint collections classes http://bugs.python.org/issue23870 closed by serhiy.storchaka #23983: Update example in the pty documentation http://bugs.python.org/issue23983 closed by berker.peksag #23995: msvcrt could not be imported http://bugs.python.org/issue23995 closed by r.david.murray #24013: Improve os.scandir() and DirEntry documentation http://bugs.python.org/issue24013 closed by python-dev #24017: Implemenation of the PEP 492 - Coroutines with async and await http://bugs.python.org/issue24017 closed by yselivanov #24018: add a Generator ABC http://bugs.python.org/issue24018 closed by rhettinger #24032: urlparse.urljoin does not add query part http://bugs.python.org/issue24032 closed by r.david.murray #24042: Convert os._getfullpathname() and os._isdir() to Argument Clin http://bugs.python.org/issue24042 closed by serhiy.storchaka #24064: Make the property doctstring writeable http://bugs.python.org/issue24064 closed by rhettinger #24138: Speed up range() by caching and modifying long objects http://bugs.python.org/issue24138 closed by larry #24149: Issue with unit tests http://bugs.python.org/issue24149 closed by ned.deily #24150: text_contextlib fails on Mac OSX 10.10.3 http://bugs.python.org/issue24150 closed by ned.deily #24155: Optimize heapify for better cache utililzation http://bugs.python.org/issue24155 closed by rhettinger #24156: test.test_ssl.ThreadedTests unit test failed http://bugs.python.org/issue24156 closed by ned.deily #24158: Error of the hint of upgrading pip http://bugs.python.org/issue24158 closed by dstufft #24161: PyIter_Check returns false positive for objects of type instan http://bugs.python.org/issue24161 closed by rhettinger #24167: 2.4.X links on www.python.org/downloads/windows point to the w http://bugs.python.org/issue24167 closed by berker.peksag #24170: IDLE crashes when I press ^ key http://bugs.python.org/issue24170 closed by ned.deily #24171: httplib http://bugs.python.org/issue24171 closed by r.david.murray #24178: asyncio: support 'async with' for locks http://bugs.python.org/issue24178 closed by yselivanov #24179: asyncio: support 'async for' for StreamReader http://bugs.python.org/issue24179 closed by yselivanov #24183: ABCMeta classes do not support the **kwargs standard class int http://bugs.python.org/issue24183 closed by r.david.murray #24184: PEP 492: Add AsyncIterator and AsyncIterable to collections.ab http://bugs.python.org/issue24184 closed by yselivanov #24185: Add Function for Sending File to Trash (or Recycling Bin) http://bugs.python.org/issue24185 closed by r.david.murray #24187: del statement documentation doesn't mention name binding behav http://bugs.python.org/issue24187 closed by jc13 #24188: Signature objects not hashable http://bugs.python.org/issue24188 closed by pitrou #24189: Parameter doesn't expose its index http://bugs.python.org/issue24189 closed by yselivanov #24191: BoundArguments.signature not documented http://bugs.python.org/issue24191 closed by yselivanov #24196: Fail to create file if name starts with prn. http://bugs.python.org/issue24196 closed by pitrou #24197: minidom parses comments wrongly http://bugs.python.org/issue24197 closed by ned.deily #24202: Multiprocessing Pool not working for userdefined function http://bugs.python.org/issue24202 closed by paul.moore

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Re: [Python-Dev] cpython: inspect: Micro-optimize __eq__ for Signature, Parameter and BoundArguments
by Serhiy Storchaka 15 May '15

15 May '15

On 15.05.15 01:23, yury.selivanov wrote: > https://hg.python.org/cpython/rev/f0b10980b19e > changeset: 96056:f0b10980b19e > parent: 96054:15701e89d710 > user: Yury Selivanov <yselivanov(a)sprymix.com> > date: Thu May 14 18:20:01 2015 -0400 > summary: > inspect: Micro-optimize __eq__ for Signature, Parameter and BoundArguments > > Provide __ne__ method for consistency. > > files: > Lib/inspect.py | 32 ++++++++++++++++++++++---------- > 1 files changed, 22 insertions(+), 10 deletions(-) > > > diff --git a/Lib/inspect.py b/Lib/inspect.py > --- a/Lib/inspect.py > +++ b/Lib/inspect.py > @@ -2353,11 +2353,15 @@ > return hash((self.name, self.kind, self.annotation, self.default)) > > def __eq__(self, other): > - return (issubclass(other.__class__, Parameter) and > - self._name == other._name and > - self._kind == other._kind and > - self._default == other._default and > - self._annotation == other._annotation) > + return (self is other or > + (issubclass(other.__class__, Parameter) and > + self._name == other._name and > + self._kind == other._kind and > + self._default == other._default and > + self._annotation == other._annotation)) It would be better to return NotImplemented if other is not an instance of Parameter. if self is other: return True if not isinstance(other, Parameter): return NotImplemented return (self._name == other._name and self._kind == other._kind and self._default == other._default and self._annotation == other._annotation) And why you use issubclass() instead of isinstance()? > + def __ne__(self, other): > + return not self.__eq__(other) This is not need (and incorrect if __eq__ returns NotImplemented). The default __ne__ implementations calls __eq__ and correctly handles NotImplemented.

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PEP 455 -- TransformDict
by Raymond Hettinger 15 May '15

15 May '15

Before the Python 3.5 feature freeze, I should step-up and formally reject PEP 455 for "Adding a key-transforming dictionary to collections". I had completed an involved review effort a long time ago and I apologize for the delay in making the pronouncement. What made it a interesting choice from the outset is that the idea of a "transformation" is an enticing concept that seems full of possibility. I spent a good deal of time exploring what could be done with it but found that it mostly fell short of its promise. There were many issues. Here are some that were at the top: * Most use cases don't need or want the reverse lookup feature (what is wanted is a set of one-way canonicalization functions). Those that do would want to have a choice of what is saved (first stored, last stored, n most recent, a set of all inputs, a list of all inputs, nothing, etc). In database terms, it models a many-to-one table (the canonicalization or transformation function) with the one being a primary key into another possibly surjective table of two columns (the key/value store). A surjection into another surjection isn't inherently reversible in a useful way, nor does it seem to be a common way to model data. * People are creative at coming up with using cases for the TD but then find that the resulting code is less clear, slower, less intuitive, more memory intensive, and harder to debug than just using a plain dict with a function call before the lookup: d[func(key)]. It was challenging to find any existing code that would be made better by the availability of the TD. * The TD seems to be all about combining data scrubbing (case-folding, unicode canonicalization, type-folding, object identity, unit-conversion, or finding a canonical member of an equivalence class) with a mapping (looking-up a value for a given key). Those two operations are conceptually orthogonal. The former doesn't get easier when hidden behind a mapping API and the latter loses the flexibility of choosing your preferred mapping (an ordereddict, a persistentdict, a chainmap, etc) and the flexibility of establishing your own rules for whether and how to do a reverse lookup. Raymond Hettinger P.S. Besides the core conceptual issues listed above, there are a number of smaller issues with the TD that surfaced during design review sessions. In no particular order, here are a few of the observations: * It seems to require above average skill to figure-out what can be used as a transform function. It is more expert-friendly than beginner friendly. It takes a little while to get used to it. It wasn't self-evident that transformations happen both when a key is stored and again when it is looked-up (contrast this with key-functions for sorting which are called at most once per key). * The name, TransformDict, suggests that it might transform the value instead of the key or that it might transform the dictionary into something else. The name TransformDict is so general that it would be hard to discover when faced with a specific problem. The name also limits perception of what could be done with it (i.e. a function that logs accesses but doesn't actually change the key). * The tool doesn't self describe itself well. Looking at the help(), or the __repr__(), or the tooltips did not provide much insight or clarity. The dir() shows many of the _abc implementation details rather than the API itself. * The original key is stored and if you change it, the change isn't stored. The _original dict is private (perhaps to reduce the risk of putting the TD in an inconsistent state) but this limits access to the stored data. * The TD is unsuitable for bijections because the API is inherently biased with a rich group of operators and methods for forward lookup but has only one method for reverse lookup. * The reverse feature is hard to find (getitem vs __getitem__) and its output pair is surprising and a bit awkward to use. It provides only one accessor method rather that the full dict API that would be given by a second dictionary. The API hides the fact that there are two underlying dictionaries. * It was surprising that when d[k] failed, it failed with transformation exception rather than a KeyError, violating the expectations of the calling code (for example, if the transformation function is int(), the call d["12"] transforms to d[12] and either succeeds in returning a value or in raising a KeyError, but the call d["12.0"] fails with a TypeError). The latter issue limits its substitutability into existing code that expects real mappings and for exposing to end-users as if it were a normal dictionary. * There were other issues with dict invariants as well and these affected substitutability in a sometimes subtle way. For example, the TD does not work with __missing__(). Also, "k in td" does not imply that "k in list(td.keys())". * The API is at odds with wanting to access the transformations. You pay a transformation cost both when storing and when looking up, but you can't access the transformed value itself. For example, if the transformation is a function that scrubs hand entered mailing addresses and puts them into a standard format with standard abbreviations, you have no way of getting back to the cleaned-up address. * One design reviewer summarized her thoughts like this: "There is a learning curve to be climbed to figure out what it does, how to use it, and what the applications [are]. But, the [working out the same] examplea with plain dicts requires only basic knowledge." -- Patricia

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Mac popups running make test
by Skip Montanaro 14 May '15

14 May '15

I haven't run the test suite in awhile. I am in the midst of running it on my Mac running Yosemite 10.10.3. Twice now, I've gotten this popup: I assume this is testing some server listening on localhost. Is this a new thing, either with the Python test suite or with Mac OS X? (I'd normally be hidden behind a NAT firewall, but at the moment I am on a miserable public connection in a Peet's Coffee, so it takes on slightly more importance...) I've also seen the Crash Reporter pop up many times, but as far as I could tell, in all cases the test suite output told me it was expected. Perhaps tests which listen for network connections should also mention that, at least on Macs? Thx, Skip

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