Mailman 3 July 2015 - Python-Dev

PEP 448 review
by Guido van Rossum March 29, 2023

March 29, 2023

I'm back, I've re-read the PEP, and I've re-read the long thread with "(no subject)". I think Georg Brandl nailed it: """ *I like the "sequence and dict flattening" part of the PEP, mostly because itis consistent and should be easy to understand, but the comprehension syntaxenhancements seem to be bad for readability and "comprehending" what the codedoes.The call syntax part is a mixed bag on the one hand it is nice to be consistent with the extended possibilities in literals (flattening), but on the other hand there would be small but annoying inconsistencies anyways (e.g. the duplicate kwarg case above).* """ Greg Ewing followed up explaining that the inconsistency between dict flattening and call syntax is inherent in the pre-existing different rules for dicts vs. keyword args: {'a':1, 'a':2} results in {'a':2}, while f(a=1, a=2) is an error. (This form is a SyntaxError; the dynamic case f(a=1, **{'a': 1}) is a TypeError.) For me, allowing f(*a, *b) and f(**d, **e) and all the other combinations for function calls proposed by the PEP is an easy +1 -- it's a straightforward extension of the existing pattern, and anybody who knows what f(x, *a) does will understand f(x, *a, y, *b). Guessing what f(**d, **e) means shouldn't be hard either. Understanding the edge case for duplicate keys with f(**d, **e) is a little harder, but the error messages are pretty clear, and it is not a new edge case. The sequence and dict flattening syntax proposals are also clean and logical -- we already have *-unpacking on the receiving side, so allowing *x in tuple expressions reads pretty naturally (and the similarity with *a in argument lists certainly helps). From here, having [a, *x, b, *y] is also natural, and then the extension to other displays is natural: {a, *x, b, *y} and {a:1, **d, b:2, **e}. This, too, gets a +1 from me. So that leaves comprehensions. IIRC, during the development of the patch we realized that f(*x for x in xs) is sufficiently ambiguous that we decided to disallow it -- note that f(x for x in xs) is already somewhat of a special case because an argument can only be a "bare" generator expression if it is the only argument. The same reasoning doesn't apply (in that form) to list, set and dict comprehensions -- while f(x for x in xs) is identical in meaning to f((x for x in xs)), [x for x in xs] is NOT the same as [(x for x in xs)] (that's a list of one element, and the element is a generator expression). The basic premise of this part of the proposal is that if you have a few iterables, the new proposal (without comprehensions) lets you create a list or generator expression that iterates over all of them, essentially flattening them: >>> xs = [1, 2, 3] >>> ys = ['abc', 'def'] >>> zs = [99] >>> [*xs, *ys, *zs] [1, 2, 3, 'abc', 'def', 99] >>> But now suppose you have a list of iterables: >>> xss = [[1, 2, 3], ['abc', 'def'], [99]] >>> [*xss[0], *xss[1], *xss[2]] [1, 2, 3, 'abc', 'def', 99] >>> Wouldn't it be nice if you could write the latter using a comprehension? >>> xss = [[1, 2, 3], ['abc', 'def'], [99]] >>> [*xs for xs in xss] [1, 2, 3, 'abc', 'def', 99] >>> This is somewhat seductive, and the following is even nicer: the *xs position may be an expression, e.g.: >>> xss = [[1, 2, 3], ['abc', 'def'], [99]] >>> [*xs[:2] for xs in xss] [1, 2, 'abc', 'def', 99] >>> On the other hand, I had to explore the possibilities here by experimenting in the interpreter, and I discovered some odd edge cases (e.g. you can parenthesize the starred expression, but that seems a syntactic accident). All in all I am personally +0 on the comprehension part of the PEP, and I like that it provides a way to "flatten" a sequence of sequences, but I think very few people in the thread have supported this part. Therefore I would like to ask Neil to update the PEP and the patch to take out the comprehension part, so that the two "easy wins" can make it into Python 3.5 (basically, I am accepting two-thirds of the PEP :-). There is some time yet until alpha 2. I would also like code reviewers (Benjamin?) to start reviewing the patch <http://bugs.python.org/issue2292>, taking into account that the comprehension part needs to be removed. -- --Guido van Rossum (python.org/~guido)

7 17

PEP 1, PEP Purpose and Guidelines
by barry＠zope.com May 18, 2021

May 18, 2021

It has been a while since I posted a copy of PEP 1 to the mailing lists and newsgroups. I've recently done some updating of a few sections, so in the interest of gaining wider community participation in the Python development process, I'm posting the latest revision of PEP 1 here. A version of the PEP is always available on-line at http://www.python.org/peps/pep-0001.html Enjoy, -Barry -------------------- snip snip -------------------- PEP: 1 Title: PEP Purpose and Guidelines Version: $Revision: 1.36 $ Last-Modified: $Date: 2002/07/29 18:34:59 $ Author: Barry A. Warsaw, Jeremy Hylton Status: Active Type: Informational Created: 13-Jun-2000 Post-History: 21-Mar-2001, 29-Jul-2002 What is a PEP? PEP stands for Python Enhancement Proposal. A PEP is a design document providing information to the Python community, or describing a new feature for Python. The PEP should provide a concise technical specification of the feature and a rationale for the feature. We intend PEPs to be the primary mechanisms for proposing new features, for collecting community input on an issue, and for documenting the design decisions that have gone into Python. The PEP author is responsible for building consensus within the community and documenting dissenting opinions. Because the PEPs are maintained as plain text files under CVS control, their revision history is the historical record of the feature proposal[1]. Kinds of PEPs There are two kinds of PEPs. A standards track PEP describes a new feature or implementation for Python. An informational PEP describes a Python design issue, or provides general guidelines or information to the Python community, but does not propose a new feature. Informational PEPs do not necessarily represent a Python community consensus or recommendation, so users and implementors are free to ignore informational PEPs or follow their advice. PEP Work Flow The PEP editor, Barry Warsaw <peps(a)python.org>, assigns numbers for each PEP and changes its status. The PEP process begins with a new idea for Python. It is highly recommended that a single PEP contain a single key proposal or new idea. The more focussed the PEP, the more successfully it tends to be. The PEP editor reserves the right to reject PEP proposals if they appear too unfocussed or too broad. If in doubt, split your PEP into several well-focussed ones. Each PEP must have a champion -- someone who writes the PEP using the style and format described below, shepherds the discussions in the appropriate forums, and attempts to build community consensus around the idea. The PEP champion (a.k.a. Author) should first attempt to ascertain whether the idea is PEP-able. Small enhancements or patches often don't need a PEP and can be injected into the Python development work flow with a patch submission to the SourceForge patch manager[2] or feature request tracker[3]. The PEP champion then emails the PEP editor <peps(a)python.org> with a proposed title and a rough, but fleshed out, draft of the PEP. This draft must be written in PEP style as described below. If the PEP editor approves, he will assign the PEP a number, label it as standards track or informational, give it status 'draft', and create and check-in the initial draft of the PEP. The PEP editor will not unreasonably deny a PEP. Reasons for denying PEP status include duplication of effort, being technically unsound, not providing proper motivation or addressing backwards compatibility, or not in keeping with the Python philosophy. The BDFL (Benevolent Dictator for Life, Guido van Rossum) can be consulted during the approval phase, and is the final arbitrator of the draft's PEP-ability. If a pre-PEP is rejected, the author may elect to take the pre-PEP to the comp.lang.python newsgroup (a.k.a. python-list(a)python.org mailing list) to help flesh it out, gain feedback and consensus from the community at large, and improve the PEP for re-submission. The author of the PEP is then responsible for posting the PEP to the community forums, and marshaling community support for it. As updates are necessary, the PEP author can check in new versions if they have CVS commit permissions, or can email new PEP versions to the PEP editor for committing. Standards track PEPs consists of two parts, a design document and a reference implementation. The PEP should be reviewed and accepted before a reference implementation is begun, unless a reference implementation will aid people in studying the PEP. Standards Track PEPs must include an implementation - in the form of code, patch, or URL to same - before it can be considered Final. PEP authors are responsible for collecting community feedback on a PEP before submitting it for review. A PEP that has not been discussed on python-list(a)python.org and/or python-dev(a)python.org will not be accepted. However, wherever possible, long open-ended discussions on public mailing lists should be avoided. Strategies to keep the discussions efficient include, setting up a separate SIG mailing list for the topic, having the PEP author accept private comments in the early design phases, etc. PEP authors should use their discretion here. Once the authors have completed a PEP, they must inform the PEP editor that it is ready for review. PEPs are reviewed by the BDFL and his chosen consultants, who may accept or reject a PEP or send it back to the author(s) for revision. Once a PEP has been accepted, the reference implementation must be completed. When the reference implementation is complete and accepted by the BDFL, the status will be changed to `Final.' A PEP can also be assigned status `Deferred.' The PEP author or editor can assign the PEP this status when no progress is being made on the PEP. Once a PEP is deferred, the PEP editor can re-assign it to draft status. A PEP can also be `Rejected'. Perhaps after all is said and done it was not a good idea. It is still important to have a record of this fact. PEPs can also be replaced by a different PEP, rendering the original obsolete. This is intended for Informational PEPs, where version 2 of an API can replace version 1. PEP work flow is as follows: Draft -> Accepted -> Final -> Replaced ^ +----> Rejected v Deferred Some informational PEPs may also have a status of `Active' if they are never meant to be completed. E.g. PEP 1. What belongs in a successful PEP? Each PEP should have the following parts: 1. Preamble -- RFC822 style headers containing meta-data about the PEP, including the PEP number, a short descriptive title (limited to a maximum of 44 characters), the names, and optionally the contact info for each author, etc. 2. Abstract -- a short (~200 word) description of the technical issue being addressed. 3. Copyright/public domain -- Each PEP must either be explicitly labelled as placed in the public domain (see this PEP as an example) or licensed under the Open Publication License[4]. 4. Specification -- The technical specification should describe the syntax and semantics of any new language feature. The specification should be detailed enough to allow competing, interoperable implementations for any of the current Python platforms (CPython, JPython, Python .NET). 5. Motivation -- The motivation is critical for PEPs that want to change the Python language. It should clearly explain why the existing language specification is inadequate to address the problem that the PEP solves. PEP submissions without sufficient motivation may be rejected outright. 6. Rationale -- The rationale fleshes out the specification by describing what motivated the design and why particular design decisions were made. It should describe alternate designs that were considered and related work, e.g. how the feature is supported in other languages. The rationale should provide evidence of consensus within the community and discuss important objections or concerns raised during discussion. 7. Backwards Compatibility -- All PEPs that introduce backwards incompatibilities must include a section describing these incompatibilities and their severity. The PEP must explain how the author proposes to deal with these incompatibilities. PEP submissions without a sufficient backwards compatibility treatise may be rejected outright. 8. Reference Implementation -- The reference implementation must be completed before any PEP is given status 'Final,' but it need not be completed before the PEP is accepted. It is better to finish the specification and rationale first and reach consensus on it before writing code. The final implementation must include test code and documentation appropriate for either the Python language reference or the standard library reference. PEP Template PEPs are written in plain ASCII text, and should adhere to a rigid style. There is a Python script that parses this style and converts the plain text PEP to HTML for viewing on the web[5]. PEP 9 contains a boilerplate[7] template you can use to get started writing your PEP. Each PEP must begin with an RFC822 style header preamble. The headers must appear in the following order. Headers marked with `*' are optional and are described below. All other headers are required. PEP: <pep number> Title: <pep title> Version: <cvs version string> Last-Modified: <cvs date string> Author: <list of authors' real names and optionally, email addrs> * Discussions-To: <email address> Status: <Draft | Active | Accepted | Deferred | Final | Replaced> Type: <Informational | Standards Track> * Requires: <pep numbers> Created: <date created on, in dd-mmm-yyyy format> * Python-Version: <version number> Post-History: <dates of postings to python-list and python-dev> * Replaces: <pep number> * Replaced-By: <pep number> The Author: header lists the names and optionally, the email addresses of all the authors/owners of the PEP. The format of the author entry should be address(a)dom.ain (Random J. User) if the email address is included, and just Random J. User if the address is not given. If there are multiple authors, each should be on a separate line following RFC 822 continuation line conventions. Note that personal email addresses in PEPs will be obscured as a defense against spam harvesters. Standards track PEPs must have a Python-Version: header which indicates the version of Python that the feature will be released with. Informational PEPs do not need a Python-Version: header. While a PEP is in private discussions (usually during the initial Draft phase), a Discussions-To: header will indicate the mailing list or URL where the PEP is being discussed. No Discussions-To: header is necessary if the PEP is being discussed privately with the author, or on the python-list or python-dev email mailing lists. Note that email addresses in the Discussions-To: header will not be obscured. Created: records the date that the PEP was assigned a number, while Post-History: is used to record the dates of when new versions of the PEP are posted to python-list and/or python-dev. Both headers should be in dd-mmm-yyyy format, e.g. 14-Aug-2001. PEPs may have a Requires: header, indicating the PEP numbers that this PEP depends on. PEPs may also have a Replaced-By: header indicating that a PEP has been rendered obsolete by a later document; the value is the number of the PEP that replaces the current document. The newer PEP must have a Replaces: header containing the number of the PEP that it rendered obsolete. PEP Formatting Requirements PEP headings must begin in column zero and the initial letter of each word must be capitalized as in book titles. Acronyms should be in all capitals. The body of each section must be indented 4 spaces. Code samples inside body sections should be indented a further 4 spaces, and other indentation can be used as required to make the text readable. You must use two blank lines between the last line of a section's body and the next section heading. You must adhere to the Emacs convention of adding two spaces at the end of every sentence. You should fill your paragraphs to column 70, but under no circumstances should your lines extend past column 79. If your code samples spill over column 79, you should rewrite them. Tab characters must never appear in the document at all. A PEP should include the standard Emacs stanza included by example at the bottom of this PEP. A PEP must contain a Copyright section, and it is strongly recommended to put the PEP in the public domain. When referencing an external web page in the body of a PEP, you should include the title of the page in the text, with a footnote reference to the URL. Do not include the URL in the body text of the PEP. E.g. Refer to the Python Language web site [1] for more details. ... [1] http://www.python.org When referring to another PEP, include the PEP number in the body text, such as "PEP 1". The title may optionally appear. Add a footnote reference that includes the PEP's title and author. It may optionally include the explicit URL on a separate line, but only in the References section. Note that the pep2html.py script will calculate URLs automatically, e.g.: ... Refer to PEP 1 [7] for more information about PEP style ... References [7] PEP 1, PEP Purpose and Guidelines, Warsaw, Hylton http://www.python.org/peps/pep-0001.html If you decide to provide an explicit URL for a PEP, please use this as the URL template: http://www.python.org/peps/pep-xxxx.html PEP numbers in URLs must be padded with zeros from the left, so as to be exactly 4 characters wide, however PEP numbers in text are never padded. Reporting PEP Bugs, or Submitting PEP Updates How you report a bug, or submit a PEP update depends on several factors, such as the maturity of the PEP, the preferences of the PEP author, and the nature of your comments. For the early draft stages of the PEP, it's probably best to send your comments and changes directly to the PEP author. For more mature, or finished PEPs you may want to submit corrections to the SourceForge bug manager[6] or better yet, the SourceForge patch manager[2] so that your changes don't get lost. If the PEP author is a SF developer, assign the bug/patch to him, otherwise assign it to the PEP editor. When in doubt about where to send your changes, please check first with the PEP author and/or PEP editor. PEP authors who are also SF committers, can update the PEPs themselves by using "cvs commit" to commit their changes. Remember to also push the formatted PEP text out to the web by doing the following: % python pep2html.py -i NUM where NUM is the number of the PEP you want to push out. See % python pep2html.py --help for details. Transferring PEP Ownership It occasionally becomes necessary to transfer ownership of PEPs to a new champion. In general, we'd like to retain the original author as a co-author of the transferred PEP, but that's really up to the original author. A good reason to transfer ownership is because the original author no longer has the time or interest in updating it or following through with the PEP process, or has fallen off the face of the 'net (i.e. is unreachable or not responding to email). A bad reason to transfer ownership is because you don't agree with the direction of the PEP. We try to build consensus around a PEP, but if that's not possible, you can always submit a competing PEP. If you are interested assuming ownership of a PEP, send a message asking to take over, addressed to both the original author and the PEP editor <peps(a)python.org>. If the original author doesn't respond to email in a timely manner, the PEP editor will make a unilateral decision (it's not like such decisions can be reversed. :). References and Footnotes [1] This historical record is available by the normal CVS commands for retrieving older revisions. For those without direct access to the CVS tree, you can browse the current and past PEP revisions via the SourceForge web site at http://cvs.sourceforge.net/cgi-bin/cvsweb.cgi/python/nondist/peps/?cvsroot=… [2] http://sourceforge.net/tracker/?group_id=5470&atid=305470 [3] http://sourceforge.net/tracker/?atid=355470&group_id=5470&func=browse [4] http://www.opencontent.org/openpub/ [5] The script referred to here is pep2html.py, which lives in the same directory in the CVS tree as the PEPs themselves. Try "pep2html.py --help" for details. The URL for viewing PEPs on the web is http://www.python.org/peps/ [6] http://sourceforge.net/tracker/?group_id=5470&atid=305470 [7] PEP 9, Sample PEP Template http://www.python.org/peps/pep-0009.html Copyright This document has been placed in the public domain. Local Variables: mode: indented-text indent-tabs-mode: nil sentence-end-double-space: t fill-column: 70 End:

8 14

What's New editing
by R. David Murray Sept. 8, 2015

Sept. 8, 2015

Just so people aren't caught unawares, it is very unlikely that I will have time to be the final editor on "What's New for 3.5" they way I was for 3.3 and 3.4. I've tried to encourage people to keep What's New up to date, but *someone* should make a final editing pass. Ideally they'd do at least the research Serhiy did last year on checking that there's a mention for all of the versionadded and versionchanged 3.5's in the docs. Even better would be to review the NEWS and/or commit history...but *that* is a really big job these days.... --David

14 21

Burning down the backlog.
by Robert Collins Aug. 18, 2015

Aug. 18, 2015

On 21 July 2015 at 19:40, Nick Coghlan <ncoghlan(a)gmail.com> wrote: > All of this is why the chart that I believe should be worrying people > is the topmost one on this page: > http://bugs.python.org/issue?@template=stats > > Both the number of open issues and the number of open issues with > patches are steadily trending upwards. That means the bottleneck in > the current process *isn't* getting patches written in the first > place, it's getting them up to the appropriate standards and applied. > Yet the answer to the problem isn't a simple "recruit more core > developers", as the existing core developers are *also* the bottleneck > in the review and mentoring process for *new* core developers. Those charts doesn't show patches in 'commit-review' - http://bugs.python.org/issue?%40columns=title&%40columns=id&stage=5&%40colu… There are only 45 of those patches. AIUI - and I'm very new to core here - anyone in triagers can get patches up to commit-review status. I think we should set a goal to keep inventory low here - e.g. review and either bounce back to patch review, or commit, in less than a month. Now - a month isn't super low, but we have lots of stuff greater than a month. For my part, I'm going to pick up more or less one thing a day and review it, but I think it would be great if other committers were to also to do this: if we had 5 of us doing 1 a day, I think we'd burn down this 45 patch backlog rapidly without significant individual cost. At which point, we can fairly say to folk doing triage that we're ready for patches :) -Rob -- Robert Collins <rbtcollins(a)hp.com> Distinguished Technologist HP Converged Cloud

10 13

PEP 447 (type.__getdescriptor__)
by Ronald Oussoren Aug. 5, 2015

Aug. 5, 2015

Hi, Another summer with another EuroPython, which means its time again to try to revive PEP 447… I’ve just pushes a minor update to the PEP and would like to get some feedback on this, arguably fairly esoteric, PEP. The PEP proposes to to replace direct access to the class __dict__ in object.__getattribute__ and super.__getattribute__ by calls to a new special method to give the metaclass more control over attribute lookup, especially for access using a super() object. This is needed for classes that cannot store (all) descriptors in the class dict for some reason, see the PEP text for a real-world example of that. Regards, Ronald The PEP text (with an outdated section with benchmarks removed): PEP: 447 Title: Add __getdescriptor__ method to metaclass Version: $Revision$ Last-Modified: $Date$ Author: Ronald Oussoren <ronaldoussoren(a)mac.com> Status: Draft Type: Standards Track Content-Type: text/x-rst Created: 12-Jun-2013 Post-History: 2-Jul-2013, 15-Jul-2013, 29-Jul-2013, 22-Jul-2015 Abstract ======== Currently ``object.__getattribute__`` and ``super.__getattribute__`` peek in the ``__dict__`` of classes on the MRO for a class when looking for an attribute. This PEP adds an optional ``__getdescriptor__`` method to a metaclass that replaces this behavior and gives more control over attribute lookup, especially when using a `super`_ object. That is, the MRO walking loop in ``_PyType_Lookup`` and ``super.__getattribute__`` gets changed from:: def lookup(mro_list, name): for cls in mro_list: if name in cls.__dict__: return cls.__dict__ return NotFound to:: def lookup(mro_list, name): for cls in mro_list: try: return cls.__getdescriptor__(name) except AttributeError: pass return NotFound The default implemention of ``__getdescriptor__`` looks in the class dictionary:: class type: def __getdescriptor__(cls, name): try: return cls.__dict__[name] except KeyError: raise AttributeError(name) from None Rationale ========= It is currently not possible to influence how the `super class`_ looks up attributes (that is, ``super.__getattribute__`` unconditionally peeks in the class ``__dict__``), and that can be problematic for dynamic classes that can grow new methods on demand. The ``__getdescriptor__`` method makes it possible to dynamically add attributes even when looking them up using the `super class`_. The new method affects ``object.__getattribute__`` (and `PyObject_GenericGetAttr`_) as well for consistency and to have a single place to implement dynamic attribute resolution for classes. Background ---------- The current behavior of ``super.__getattribute__`` causes problems for classes that are dynamic proxies for other (non-Python) classes or types, an example of which is `PyObjC`_. PyObjC creates a Python class for every class in the Objective-C runtime, and looks up methods in the Objective-C runtime when they are used. This works fine for normal access, but doesn't work for access with `super`_ objects. Because of this PyObjC currently includes a custom `super`_ that must be used with its classes, as well as completely reimplementing `PyObject_GenericGetAttr`_ for normal attribute access. The API in this PEP makes it possible to remove the custom `super`_ and simplifies the implementation because the custom lookup behavior can be added in a central location. .. note:: `PyObjC`_ cannot precalculate the contents of the class ``__dict__`` because Objective-C classes can grow new methods at runtime. Furthermore Objective-C classes tend to contain a lot of methods while most Python code will only use a small subset of them, this makes precalculating unnecessarily expensive. The superclass attribute lookup hook ==================================== Both ``super.__getattribute__`` and ``object.__getattribute__`` (or `PyObject_GenericGetAttr`_ and in particular ``_PyType_Lookup`` in C code) walk an object's MRO and currently peek in the class' ``__dict__`` to look up attributes. With this proposal both lookup methods no longer peek in the class ``__dict__`` but call the special method ``__getdescriptor__``, which is a slot defined on the metaclass. The default implementation of that method looks up the name the class ``__dict__``, which means that attribute lookup is unchanged unless a metatype actually defines the new special method. Aside: Attribute resolution algorithm in Python ----------------------------------------------- The attribute resolution proces as implemented by ``object.__getattribute__`` (or PyObject_GenericGetAttr`` in CPython's implementation) is fairly straightforward, but not entirely so without reading C code. The current CPython implementation of object.__getattribute__ is basicly equivalent to the following (pseudo-) Python code (excluding some house keeping and speed tricks):: def _PyType_Lookup(tp, name): mro = tp.mro() assert isinstance(mro, tuple) for base in mro: assert isinstance(base, type) # PEP 447 will change these lines: try: return base.__dict__[name] except KeyError: pass return None class object: def __getattribute__(self, name): assert isinstance(name, str) tp = type(self) descr = _PyType_Lookup(tp, name) f = None if descr is not None: f = descr.__get__ if f is not None and descr.__set__ is not None: # Data descriptor return f(descr, self, type(self)) dict = self.__dict__ if dict is not None: try: return self.__dict__[name] except KeyError: pass if f is not None: # Non-data descriptor return f(descr, self, type(self)) if descr is not None: # Regular class attribute return descr raise AttributeError(name) class super: def __getattribute__(self, name): assert isinstance(name, unicode) if name != '__class__': starttype = self.__self_type__ mro = startype.mro() try: idx = mro.index(self.__thisclass__) except ValueError: pass else: for base in mro[idx+1:]: # PEP 447 will change these lines: try: descr = base.__dict__[name] except KeyError: continue f = descr.__get__ if f is not None: return f(descr, None if (self.__self__ is self.__self_type__) else self.__self__, starttype) else: return descr return object.__getattribute__(self, name) This PEP should change the dict lookup at the lines starting at "# PEP 447" with a method call to perform the actual lookup, making is possible to affect that lookup both for normal attribute access and access through the `super proxy`_. Note that specific classes can already completely override the default behaviour by implementing their own ``__getattribute__`` slot (with or without calling the super class implementation). In Python code -------------- A meta type can define a method ``__getdescriptor__`` that is called during attribute resolution by both ``super.__getattribute__`` and ``object.__getattribute``:: class MetaType(type): def __getdescriptor__(cls, name): try: return cls.__dict__[name] except KeyError: raise AttributeError(name) from None The ``__getdescriptor__`` method has as its arguments a class (which is an instance of the meta type) and the name of the attribute that is looked up. It should return the value of the attribute without invoking descriptors, and should raise `AttributeError`_ when the name cannot be found. The `type`_ class provides a default implementation for ``__getdescriptor__``, that looks up the name in the class dictionary. Example usage ............. The code below implements a silly metaclass that redirects attribute lookup to uppercase versions of names:: class UpperCaseAccess (type): def __getdescriptor__(cls, name): try: return cls.__dict__[name.upper()] except KeyError: raise AttributeError(name) from None class SillyObject (metaclass=UpperCaseAccess): def m(self): return 42 def M(self): return "fourtytwo" obj = SillyObject() assert obj.m() == "fortytwo" As mentioned earlier in this PEP a more realistic use case of this functionallity is a ``__getdescriptor__`` method that dynamicly populates the class ``__dict__`` based on attribute access, primarily when it is not possible to reliably keep the class dict in sync with its source, for example because the source used to populate ``__dict__`` is dynamic as well and does not have triggers that can be used to detect changes to that source. An example of that are the class bridges in PyObjC: the class bridge is a Python object (class) that represents an Objective-C class and conceptually has a Python method for every Objective-C method in the Objective-C class. As with Python it is possible to add new methods to an Objective-C class, or replace existing ones, and there are no callbacks that can be used to detect this. In C code --------- A new slot ``tp_getdescriptor`` is added to the ``PyTypeObject`` struct, this slot corresponds to the ``__getdescriptor__`` method on `type`_. The slot has the following prototype:: PyObject* (*getdescriptorfunc)(PyTypeObject* cls, PyObject* name); This method should lookup *name* in the namespace of *cls*, without looking at superclasses, and should not invoke descriptors. The method returns ``NULL`` without setting an exception when the *name* cannot be found, and returns a new reference otherwise (not a borrowed reference). Use of this hook by the interpreter ----------------------------------- The new method is required for metatypes and as such is defined on `type_`. Both ``super.__getattribute__`` and ``object.__getattribute__``/`PyObject_GenericGetAttr`_ (through ``_PyType_Lookup``) use the this ``__getdescriptor__`` method when walking the MRO. Other changes to the implementation ----------------------------------- The change for `PyObject_GenericGetAttr`_ will be done by changing the private function ``_PyType_Lookup``. This currently returns a borrowed reference, but must return a new reference when the ``__getdescriptor__`` method is present. Because of this ``_PyType_Lookup`` will be renamed to ``_PyType_LookupName``, this will cause compile-time errors for all out-of-tree users of this private API. The attribute lookup cache in ``Objects/typeobject.c`` is disabled for classes that have a metaclass that overrides ``__getdescriptor__``, because using the cache might not be valid for such classes. Impact of this PEP on introspection ----------------------------------- Use of the method introduced in this PEP can affect introspection of classes with a metaclass that uses a custom ``__getdescriptor__`` method. This section lists those changes. The items listed below are only affected by custom ``__getdescriptor__`` methods, the default implementation for ``object`` won't cause problems because that still only uses the class ``__dict__`` and won't cause visible changes to the visible behaviour of the ``object.__getattribute__``. * ``dir`` might not show all attributes As with a custom ``__getattribute__`` method `dir()`_ might not see all (instance) attributes when using the ``__getdescriptor__()`` method to dynamicly resolve attributes. The solution for that is quite simple: classes using ``__getdescriptor__`` should also implement `__dir__()`_ if they want full support for the builtin `dir()`_ function. * ``inspect.getattr_static`` might not show all attributes The function ``inspect.getattr_static`` intentionally does not invoke ``__getattribute__`` and descriptors to avoid invoking user code during introspection with this function. The ``__getdescriptor__`` method will also be ignored and is another way in which the result of ``inspect.getattr_static`` can be different from that of ``builtin.getattr``. * ``inspect.getmembers`` and ``inspect.get_class_attrs`` Both of these functions directly access the class __dict__ of classes along the MRO, and hence can be affected by a custom ``__getdescriptor__`` method. **TODO**: I haven't fully worked out what the impact of this is, and if there are mitigations for those using either updates to these functions, or additional methods that users should implement to be fully compatible with these functions. One possible mitigation is to have a custom ``__getattribute__`` for these classes that fills ``__dict__`` before returning and and defers to the default implementation for other attributes. * Direct introspection of the class ``__dict__`` Any code that directly access the class ``__dict__`` for introspection can be affected by a custom ``__getdescriptor__`` method. Performance impact ------------------ **WARNING**: The benchmark results in this section are old, and will be updated when I've ported the patch to the current trunk. I don't expect significant changes to the results in this section. [snipped] Alternative proposals --------------------- ``__getattribute_super__`` .......................... An earlier version of this PEP used the following static method on classes:: def __getattribute_super__(cls, name, object, owner): pass This method performed name lookup as well as invoking descriptors and was necessarily limited to working only with ``super.__getattribute__``. Reuse ``tp_getattro`` ..................... It would be nice to avoid adding a new slot, thus keeping the API simpler and easier to understand. A comment on `Issue 18181`_ asked about reusing the ``tp_getattro`` slot, that is super could call the ``tp_getattro`` slot of all methods along the MRO. That won't work because ``tp_getattro`` will look in the instance ``__dict__`` before it tries to resolve attributes using classes in the MRO. This would mean that using ``tp_getattro`` instead of peeking the class dictionaries changes the semantics of the `super class`_. Alternate placement of the new method ..................................... This PEP proposes to add ``__getdescriptor__`` as a method on the metaclass. An alternative would be to add it as a class method on the class itself (simular to how ``__new__`` is a `staticmethod`_ of the class and not a method of the metaclass). The two are functionally equivalent, and there's something to be said about not requiring the use of a meta class. References ========== * `Issue 18181`_ contains an out of date prototype implementation Copyright ========= This document has been placed in the public domain. .. _`Issue 18181`: http://bugs.python.org/issue18181 .. _`super class`: http://docs.python.org/3/library/functions.html#super .. _`super proxy`: http://docs.python.org/3/library/functions.html#super .. _`super`: http://docs.python.org/3/library/functions.html#super .. _`dir()`: http://docs.python.org/3/library/functions.html#dir .. _`staticmethod`: http://docs.python.org/3/library/functions.html#staticmethod .. _`__dir__()`: https://docs.python.org/3/reference/datamodel.html#object.__dir__ .. _`NotImplemented`: http://docs.python.org/3/library/constants.html#NotImplemented .. _`PyObject_GenericGetAttr`: http://docs.python.org/3/c-api/object.html#PyObject_GenericGetAttr .. _`type`: http://docs.python.org/3/library/functions.html#type .. _`AttributeError`: http://docs.python.org/3/library/exceptions.html#AttributeError .. _`PyObjC`: http://pyobjc.sourceforge.net/ .. _`classmethod`: http://docs.python.org/3/library/functions.html#classmethod

8 19

Issues not responded to.
by Mark Lawrence Aug. 1, 2015

Aug. 1, 2015

There are over 400 issues on the bug tracker that have not had a response to the initial message, roughly half of these within the last eight months alone. Is there a (relatively) simple way that we can share these out between us to sort those that are likely to need dealing with in the medium to longer term, from the simple short term ones, e.g very easy typo fixes? -- My fellow Pythonistas, ask not what our language can do for you, ask what you can do for our language. Mark Lawrence

9 8

Summary of Python tracker Issues
by Python tracker July 31, 2015

July 31, 2015

ACTIVITY SUMMARY (2015-07-24 - 2015-07-31) 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 4961 ( +4) closed 31563 (+52) total 36524 (+56) Open issues with patches: 2246 Issues opened (36) ================== #23447: Import fails when doing a circular import involving an `import http://bugs.python.org/issue23447 reopened by rbcollins #24476: Statically link vcruntime140.dll http://bugs.python.org/issue24476 reopened by steve.dower #24709: Unix build uses '-Wno-unused-result', which icc doesn't recogn http://bugs.python.org/issue24709 opened by zach.ware #24710: Class name hardcoded in TracebackException.from_exception() http://bugs.python.org/issue24710 opened by berker.peksag #24711: Document getpass.getpass behavior on ^C http://bugs.python.org/issue24711 opened by untitaker #24712: Docs page's sidebar vibrates on mouse wheel scroll on Chrome. http://bugs.python.org/issue24712 opened by Biwin John #24715: Sorting HOW TO: bad example for reverse sort stability http://bugs.python.org/issue24715 opened by jwilk #24718: Specify interpreter when running in IDLE http://bugs.python.org/issue24718 opened by Daniel Pope #24720: Python install help http://bugs.python.org/issue24720 opened by node #24724: Element.findall documentation misleading http://bugs.python.org/issue24724 opened by Eric S #24725: test_socket testFDPassEmpty fails on OS X 10.11 DP with "Canno http://bugs.python.org/issue24725 opened by ned.deily #24726: OrderedDict has strange behaviour when dict.__setitem__ is use http://bugs.python.org/issue24726 opened by Mark.Shannon #24727: Expand readline module http://bugs.python.org/issue24727 opened by Barney Stratford #24731: Incorrect assert in str_subtype_new http://bugs.python.org/issue24731 opened by Kevin Modzelewski #24732: 3.5.0b3 Windows accept() on unready non-blocking socket raises http://bugs.python.org/issue24732 opened by bryangeneolson #24733: Logically Dead Code http://bugs.python.org/issue24733 opened by pankaj.s01 #24736: argparse add_mutually_exclusive_group do not print help http://bugs.python.org/issue24736 opened by Alexandre.Badez #24739: allow argparse.FileType to accept newline argument http://bugs.python.org/issue24739 opened by garyp #24740: make patchcheck doesn't detect changes if commit is done first http://bugs.python.org/issue24740 opened by rbcollins #24743: Make _PyTraceback_Add public http://bugs.python.org/issue24743 opened by mic-e #24744: Lack of type checks in pkgutil.walk_packages and friends http://bugs.python.org/issue24744 opened by sleepycal #24745: Better default font for editor http://bugs.python.org/issue24745 opened by markroseman #24746: doctest 'fancy diff' formats incorrectly strip trailing whites http://bugs.python.org/issue24746 opened by r.david.murray #24747: ctypes silently truncates ints larger than C int http://bugs.python.org/issue24747 opened by encukou #24748: Change of behavior for importlib between 3.4 and 3.5 with DLL http://bugs.python.org/issue24748 opened by ebfortin #24750: IDLE: Cosmetic improvements for main window http://bugs.python.org/issue24750 opened by markroseman #24751: regrtest/buildbot: test run marked as failure even when re-run http://bugs.python.org/issue24751 opened by zach.ware #24752: SystemError when importing from a non-package directory http://bugs.python.org/issue24752 opened by fossilet #24754: argparse add_argument with action="store_true", type=bool shou http://bugs.python.org/issue24754 opened by dbagnall #24755: asyncio.wrap_future undocumented http://bugs.python.org/issue24755 opened by wodny #24756: doctest run_docstring_examples does have an obvious utility http://bugs.python.org/issue24756 opened by r.david.murray #24757: Installing Py on Windows: Need to restart or logout for path t http://bugs.python.org/issue24757 opened by John Palermo #24758: unittest.mock.Mock's new "unsafe" feature needs a better error http://bugs.python.org/issue24758 opened by Randy Syring #24760: IDLE settings dialog shouldn't be modal http://bugs.python.org/issue24760 opened by markroseman #24761: ERROR: test_dh_params (test.test_ssl.ThreadedTests) http://bugs.python.org/issue24761 opened by cloud2han9 #24762: Branchless, vectorizable frozen set hash http://bugs.python.org/issue24762 opened by rhettinger Most recent 15 issues with no replies (15) ========================================== #24762: Branchless, vectorizable frozen set hash http://bugs.python.org/issue24762 #24761: ERROR: test_dh_params (test.test_ssl.ThreadedTests) http://bugs.python.org/issue24761 #24755: asyncio.wrap_future undocumented http://bugs.python.org/issue24755 #24746: doctest 'fancy diff' formats incorrectly strip trailing whites http://bugs.python.org/issue24746 #24743: Make _PyTraceback_Add public http://bugs.python.org/issue24743 #24740: make patchcheck doesn't detect changes if commit is done first http://bugs.python.org/issue24740 #24739: allow argparse.FileType to accept newline argument http://bugs.python.org/issue24739 #24736: argparse add_mutually_exclusive_group do not print help http://bugs.python.org/issue24736 #24733: Logically Dead Code http://bugs.python.org/issue24733 #24731: Incorrect assert in str_subtype_new http://bugs.python.org/issue24731 #24727: Expand readline module http://bugs.python.org/issue24727 #24718: Specify interpreter when running in IDLE http://bugs.python.org/issue24718 #24715: Sorting HOW TO: bad example for reverse sort stability http://bugs.python.org/issue24715 #24711: Document getpass.getpass behavior on ^C http://bugs.python.org/issue24711 #24709: Unix build uses '-Wno-unused-result', which icc doesn't recogn http://bugs.python.org/issue24709 Most recent 15 issues waiting for review (15) ============================================= #24762: Branchless, vectorizable frozen set hash http://bugs.python.org/issue24762 #24756: doctest run_docstring_examples does have an obvious utility http://bugs.python.org/issue24756 #24751: regrtest/buildbot: test run marked as failure even when re-run http://bugs.python.org/issue24751 #24750: IDLE: Cosmetic improvements for main window http://bugs.python.org/issue24750 #24746: doctest 'fancy diff' formats incorrectly strip trailing whites http://bugs.python.org/issue24746 #24733: Logically Dead Code http://bugs.python.org/issue24733 #24724: Element.findall documentation misleading http://bugs.python.org/issue24724 #24715: Sorting HOW TO: bad example for reverse sort stability http://bugs.python.org/issue24715 #24710: Class name hardcoded in TracebackException.from_exception() http://bugs.python.org/issue24710 #24698: get_externals.bat script fails http://bugs.python.org/issue24698 #24693: zipfile: change RuntimeError to more appropriate exception typ http://bugs.python.org/issue24693 #24692: types.coroutines() idempotence documentation http://bugs.python.org/issue24692 #24682: Add Quick Start: Communications section to devguide http://bugs.python.org/issue24682 #24674: pyclbr not recursively showing classes in packages http://bugs.python.org/issue24674 #24673: distutils/_msvccompiler does not remove /DLL during link(CComp http://bugs.python.org/issue24673 Top 10 most discussed issues (10) ================================= #24667: OrderedDict.popitem()/__str__() raises KeyError http://bugs.python.org/issue24667 14 msgs #24748: Change of behavior for importlib between 3.4 and 3.5 with DLL http://bugs.python.org/issue24748 13 msgs #24720: Python install help http://bugs.python.org/issue24720 12 msgs #24750: IDLE: Cosmetic improvements for main window http://bugs.python.org/issue24750 12 msgs #18378: locale.getdefaultlocale() fails on Mac OS X with default langu http://bugs.python.org/issue18378 8 msgs #19450: Bug in sqlite in Windows binaries http://bugs.python.org/issue19450 7 msgs #24732: 3.5.0b3 Windows accept() on unready non-blocking socket raises http://bugs.python.org/issue24732 7 msgs #20059: Inconsistent urlparse/urllib.parse handling of invalid port va http://bugs.python.org/issue20059 6 msgs #23496: Steps for Android Native Build of Python 3.4.2 http://bugs.python.org/issue23496 6 msgs #24651: Mock.assert* API is in user namespace http://bugs.python.org/issue24651 6 msgs Issues closed (52) ================== #2091: file accepts 'rU+' as a mode http://bugs.python.org/issue2091 closed by rbcollins #12160: codecs doc: what is StreamCodec? http://bugs.python.org/issue12160 closed by berker.peksag #13884: IDLE: Remove tear-off menu feature http://bugs.python.org/issue13884 closed by terry.reedy #17527: PATCH as valid request method in wsgiref.validator http://bugs.python.org/issue17527 closed by rbcollins #17991: ctypes.c_char gives a misleading error when passed a one-chara http://bugs.python.org/issue17991 closed by Steven.Barker #20051: PA-RISC buildbot: compiler cannot create executables http://bugs.python.org/issue20051 closed by zach.ware #20366: SQLite FTS (full text search) http://bugs.python.org/issue20366 closed by mark #20544: Use specific asserts in operator tests http://bugs.python.org/issue20544 closed by python-dev #20551: Use specific asserts in decimal tests http://bugs.python.org/issue20551 closed by skrah #21657: pip.get_installed_distributions() Does not return packages in http://bugs.python.org/issue21657 closed by zach.ware #21697: shutil.copytree() handles symbolic directory incorrectly http://bugs.python.org/issue21697 closed by berker.peksag #21750: mock_open data is visible only once for the life of the class http://bugs.python.org/issue21750 closed by rbcollins #23254: Document how to close the TCPServer listening socket http://bugs.python.org/issue23254 closed by rbcollins #23319: Missing SWAP_INT in I_set_sw http://bugs.python.org/issue23319 closed by haypo #23426: run_setup is broken in distutils http://bugs.python.org/issue23426 closed by rbcollins #23441: rlcompleter: tab on empty prefix => insert spaces http://bugs.python.org/issue23441 closed by berker.peksag #23589: Redundant sentence in FAQ http://bugs.python.org/issue23589 closed by rbcollins #23779: imaplib authenticate raises TypeError if authenticator tries t http://bugs.python.org/issue23779 closed by rbcollins #23899: HTTP regression in distutils uploads to chishop http://bugs.python.org/issue23899 closed by jason.coombs #23931: Update DevGuide link in Quickstart Step 1 http://bugs.python.org/issue23931 closed by berker.peksag #24109: Documentation for difflib uses optparse http://bugs.python.org/issue24109 closed by berker.peksag #24279: Update test_base64 to use test.support.script_helper http://bugs.python.org/issue24279 closed by berker.peksag #24360: improve argparse.Namespace __repr__ for invalid identifiers. http://bugs.python.org/issue24360 closed by berker.peksag #24420: Documentation regressions from adding subprocess.run() http://bugs.python.org/issue24420 closed by berker.peksag #24603: Update OpenSSL to 1.0.2d in Windows and OS X installer http://bugs.python.org/issue24603 closed by ned.deily #24613: array.fromstring Use After Free http://bugs.python.org/issue24613 closed by serhiy.storchaka #24621: zipfile.BadZipFile: File is not a zip file http://bugs.python.org/issue24621 closed by serhiy.storchaka #24645: logging.handlers.QueueHandler should not lock when handling a http://bugs.python.org/issue24645 closed by vinay.sajip #24681: Put most likely test first in set_add_entry() http://bugs.python.org/issue24681 closed by rhettinger #24683: Type confusion in json encoding http://bugs.python.org/issue24683 closed by serhiy.storchaka #24708: strop.replace Integer Overflow http://bugs.python.org/issue24708 closed by python-dev #24713: Import docs reference the deprecated imp.reload http://bugs.python.org/issue24713 closed by berker.peksag #24714: Crash with string_at(None) http://bugs.python.org/issue24714 closed by haypo #24716: Multiple fdopen() on mkstemp() descriptor crashes py27 interpr http://bugs.python.org/issue24716 closed by Thomas Krijnen #24717: python logging handler not used when added after a process is http://bugs.python.org/issue24717 closed by vinay.sajip #24719: Resourc Leak in cPickle Module http://bugs.python.org/issue24719 closed by python-dev #24721: The result of calling dict.* methods on OrderedDict is undefin http://bugs.python.org/issue24721 closed by rhettinger #24722: Python install help http://bugs.python.org/issue24722 closed by zach.ware #24723: The new typing module is not documented :-( http://bugs.python.org/issue24723 closed by berker.peksag #24728: Build fails when threads are disabled http://bugs.python.org/issue24728 closed by berker.peksag #24729: Input and Output tutorial erroneously references default encod http://bugs.python.org/issue24729 closed by jason.coombs #24730: Returning a float via a method yields in an approximate value http://bugs.python.org/issue24730 closed by zach.ware #24734: Dereferencing a null returning value http://bugs.python.org/issue24734 closed by python-dev #24735: Invalid access in combinations_with_replacement() http://bugs.python.org/issue24735 closed by rhettinger #24737: Doc issue: Python 3.6 doesn't compile on Visual Studio 2010 an http://bugs.python.org/issue24737 closed by steve.dower #24738: os.link() issues on Windows & ReFS http://bugs.python.org/issue24738 closed by r.david.murray #24741: Hangs and errors while testing on Ubuntu/Intel http://bugs.python.org/issue24741 closed by r.david.murray #24742: type(dict with docstring) returns set instead of dict http://bugs.python.org/issue24742 closed by serhiy.storchaka #24749: Which fastest python-mysql connector? http://bugs.python.org/issue24749 closed by haypo #24753: function to get completion install location for setup.py? http://bugs.python.org/issue24753 closed by r.david.murray #24759: Idle: require 8.5 / ttk http://bugs.python.org/issue24759 closed by terry.reedy #24763: asyncio.BaseSubprocessTransport triggers an unavoidable Resour http://bugs.python.org/issue24763 closed by haypo

1 0

Re: [Python-Dev] Status on PEP-431 Timezones
by Isaac Schwabacher July 30, 2015

July 30, 2015

On 15-04-15, Akira Li <4kir4.1i(a)gmail.com> wrote: > Isaac Schwabacher <ischwabacher(a)wisc.edu> writes: > > > On 15-04-15, Akira Li <4kir4.1i(a)gmail.com> wrote: > >> Isaac Schwabacher <ischwabacher(a)wisc.edu> writes: > >> > ... > >> > > >> > I know that you can do datetime.now(tz), and you can do datetime(2013, > >> > 11, 3, 1, 30, tzinfo=zoneinfo('America/Chicago')), but not being able > >> > to add a time zone to an existing naive datetime is painful (and > >> > strptime doesn't even let you pass in a time zone). > >> > >> `.now(tz)` is correct. `datetime(..., tzinfo=tz)`) is wrong: if tz is a > >> pytz timezone then you may get a wrong tzinfo (LMT), you should use > >> `tz.localize(naive_dt, is_dst=False|True|None)` instead. > > > > The whole point of this thread is to finalize PEP 431, which fixes the > > problem for which `localize()` and `normalize()` are workarounds. When > > this is done, `datetime(..., tzinfo=tz)` will be correct. > > > > ijs > > The input time is ambiguous. Even if we assume PEP 431 is implemented in > some form, your code is still missing isdst parameter (or the > analog). PEP 431 won't fix it; it can't resolve the ambiguity by > itself. Notice is_dst paramter in the `tz.localize()` call (current > API). ...yeah, I forgot to throw that in there. It was supposed to be there all along. Nothing to see here, move along. > .now(tz) works even during end-of-DST transitions (current API) when the > local time is ambiguous. I know that. That's what I was complaining about-- I was trying to talk about how astimezone() was going to be inadequate even after the PEP was implemented because it couldn't turn naive datetimes into aware ones, and people were giving examples that started with aware datetimes generated by now(tz), which completely went around the point I was trying to make. But it looks like astimezone() is going to grow an is_dst parameter, and everything will be OK. ijs

28 142

How do we tell if we're helping or hindering the core development process? (was Re: How far to go with user-friendliness)
by Nick Coghlan July 29, 2015

July 29, 2015

On 20 July 2015 at 22:34, Ben Finney <ben+python(a)benfinney.id.au> wrote: > Paul Moore <p.f.moore(a)gmail.com> writes: > >> Again, I'm sorry to pick on one sentence out of context, but it cut >> straight to my biggest fear when doing a commit (on any project) - >> what if, after all the worrying and consideration I put into doing >> this commit, people disagree with me (or worse still, I made a >> mistake)? Will I be able to justify what I decided? > > That seems quite healthy to me. On a collaborative project with effects > far beyond oneself, yes, any change *should* be able to be justified > when challenged. No, that's not how this works: if folks are thinking that being a Python user, or even a CPython core developer, means that we're entitled to micromanage core developers by demanding extensive explanations for any arbitrary commit we choose, they're thoroughly mistaken. Only Guido has that privilege, and one of the reasons he's as respected as he is is his willingness to trust the experience and expertise of others and only rarely exercise his absolute authority. Folks are granted core committer privileges because we *trust their instincts*. We trust them to know when they're acting within the limits of their own expertise and experience, and we trust them to know when it would be beneficial to seek feedback from a wider audience before making up their minds. There are *many* cases where we *don't know* up front what the right answer is, so we'll actively seek consultation, whether that's through a review request on the issue tracker, a focused python-dev discussion, a more speculative discussion on python-ideas, or engaging in the full Python Enhancement Proposal process. There are also cases where we'll decide "it seems plausible that this might be a good idea, so let's try it out and see what happens in practice rather than continuing to speculate" - only ever doing things that you're already 100% certain are a good idea is a recipe for stagnation and decline (hence the "Now is better than never" line in the Zen). A feedback cycle of a few years is a relatively short time in programming language development, so if we discover with the benefit of hindsight that something that seemed plausible really was in fact a genuinely bad idea, that's why we have a deprecation process (as well as the abilty to mark new APIs as provisional). If we want a faster feedback cycle measured in days or weeks or months rather than years, then we'll find a way to make the idea available for experimentation via PyPI or at least as a cookbook recipe or in a public source repo. But the authority and responsibility to make changes, to decide what constitutes a reasonable risk, to decide which updates are appropriate to send out to tens of millions of Python users worldwide remains *ours*. Some of those decisions will be akin to deciding to paint a bikeshed blue instead of yellow (or green, or red, or chartreuse, or ...). Others will be about mitigating the observed negative consequences of a previous design decision while retaining the positive aspects. Those kinds of design decision are still more art than science - that's why our solution to them is to attempt to recruit people with the interest, ability and time needed to make them well, and then largely leave them to it. Explaining design decisions after the fact isn't about *defending* those decisions, it's about attempting to convey useful design knowledge, in order to help build new core contributors (and also because explaining something to someone else is a good way to understand it better yourself). All of this is why the chart that I believe should be worrying people is the topmost one on this page: http://bugs.python.org/issue?@template=stats Both the number of open issues and the number of open issues with patches are steadily trending upwards. That means the bottleneck in the current process *isn't* getting patches written in the first place, it's getting them up to the appropriate standards and applied. Yet the answer to the problem isn't a simple "recruit more core developers", as the existing core developers are *also* the bottleneck in the review and mentoring process for *new* core developers. In my view, those stats are a useful tool we can use to ask ourselves "Am I actually helping with this contribution, or at the very least, not causing harm?": * participating in the core-mentorship list, and actively looking for ways to improve the effectiveness of the mentorship program (that don't just queue up more work behind the existing core developer bottleneck) should help make those stats better * sponsoring or volunteering to help with the upstream projects our core workflow tools are based on (Roundup, Buildbot) or with updating our specific installations of them should help make those stats better (and also offers faster iteration cycles than core development itself) * helping core developers that have time to work on "CPython in general" rather than specific projects of interest to them to focus their attention more effectively may help make those stats better (and it would be even better if we could credit such triaging efforts appropriately) * exploring ways to extract contribution metrics from Roundup so we can have a more reliable detection mechanism for active and consistent contributors than the "Mark 1 core developer memory, aka the notoriously unreliable human brain" may help make those stats better * helping out the upstream projects for one or both of the forge.python.org proposals (Kallithea, Phabricator) that are designed (at least in part) to remove core developers from the critical path for management of the support repos like the developer guide and Python Enhancement Proposals may help make those stats better * getting more core contributors into a position where at least some of their work time can be spent on facilitating upstream contributions may help make those stats better (shifting at least some core contribution activity to paid roles is also one of the keys to countering the "free time for volunteer activities is inequitably distributed" problem) * alienating veteran core developers and encouraging them to spend their time elsewhere will contribute to making those stats worse * discouraging newly minted core developers from exercising their granted authority will contribute to making those stats worse * discouraging veteran core developers from recruiting new core developers by contributing to creating a hostile environment on the core mailing lists will *definitely* contribute to making those stats worse Make no mistake, sustainable open source development is a *genuinely hard problem*. We're in a much better position than most projects (being one of the top 5 programming languages in the world has its benefits), but we're still effectively running a giant multinational collaborative software development project with close to zero formal management support. While their are good examples we can (and are) learning from, improving the support structures for an already wildly successful open source project without alienating existing contributors isn't a task that comes with an instruction manual :) Regards, Nick. -- Nick Coghlan | ncoghlan(a)gmail.com | Brisbane, Australia

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Benchmark Results for Python Default 2015-07-24
by lp_benchmark_robot July 29, 2015

July 29, 2015

Hi Internals, This is the first message from Intel's language optimization team. We would like to provide the Python internals developer community with a daily service which will monitor latest committed patches performance regressions against well known workloads. Our aim is to run a multitude of workloads as well as real-life scenarios which the community considers relevant. The service will send daily bulletins containing latest measurements for daily variations and variations against latest stable release run on our Intel-enabled servers. The community's feedback is very important for us. For any questions, comments or suggestions you can also contact us on our mailing list lp(a)lists.01.org. You can also check our website: https://www.01.org/lp Results for project python_default-nightly, build date 2015-07-24 09:02:02 commit: 3bbd0cbfe836511dd3e05fcc30ffb5bdbfe686ea revision date: 2015-07-24 07:43:44 environment: Haswell-EP cpu: Intel(R) Xeon(R) CPU E5-2699 v3 @ 2.30GHz 2x18 cores, stepping 2, LLC 45 MB mem: 128 GB os: CentOS 7.1 kernel: Linux 3.10.0-229.4.2.el7.x86_64 Note: Baseline results were generated using release v3.4.3, with hash b4cbecbc0781e89a309d03b60a1f75f8499250e6 from 2015-02-25 12:15:33+00:00 -------------------------------------------------------------------------------- benchmark unit change since change since last run v3.4.3 -------------------------------------------------------------------------------- :-) django_v2 sec 1.12735% 7.47953% :-( pybench sec -0.53822% -2.40216% :-( regex_v8 sec 0.61774% -2.32010% :-| nbody sec 1.75860% -0.76206% :-) json_dump_v2 sec 2.13422% -0.56930% Our lab does a nightly source pull and build of the Python project and measures performance changes against the previous stable version and the previous nightly measurement. This is provided as a service to the community so that quality issues with current hardware can be identified quickly. Intel technologies' features and benefits depend on system configuration and may require enabled hardware, software or service activation. Performance varies depending on system configuration. No license (express or implied, by estoppel or otherwise) to any intellectual property rights is granted by this document. Intel disclaims all express and implied warranties, including without limitation, the implied warranties of merchantability, fitness for a particular purpose, and non-infringement, as well as any warranty arising from course of performance, course of dealing, or usage in trade. This document may contain information on products, services and/or processes in development. Contact your Intel representative to obtain the latest forecast, schedule, specifications and roadmaps. The products and services described may contain defects or errors known as errata which may cause deviations from published specifications. Current characterized errata are available on request. (C) 2015 Intel Corporation.

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