Mailman 3 May 2009 - Python-Dev

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: … [View More]$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: [View Less]

8 14

Reviving restricted mode?
by Guido van Rossum Aug. 14, 2014

Aug. 14, 2014

I've received some enthusiastic emails from someone who wants to revive restricted mode. He started out with a bunch of patches to the CPython runtime using ctypes, which he attached to an App Engine bug: http://code.google.com/p/googleappengine/issues/detail?id=671 Based on his code (the file secure.py is all you need, included in secure.tar.gz) it seems he believes the only security leaks are __subclasses__, gi_frame and gi_code. (I have since convinced him that if we add "restricted" … [View More]

19 35

PEP 382: Namespace Packages
by "Martin v. Löwis" Nov. 4, 2009

Nov. 4, 2009

I propose the following PEP for inclusion to Python 3.1. Please comment. Regards, Martin Abstract ======== Namespace packages are a mechanism for splitting a single Python package across multiple directories on disk. In current Python versions, an algorithm to compute the packages __path__ must be formulated. With the enhancement proposed here, the import machinery itself will construct the list of directories that make up the package. Terminology =========== Within this PEP, the term … [View More]package refers to Python packages as defined by Python's import statement. The term distribution refers to separately installable sets of Python modules as stored in the Python package index, and installed by distutils or setuptools. The term vendor package refers to groups of files installed by an operating system's packaging mechanism (e.g. Debian or Redhat packages install on Linux systems). The term portion refers to a set of files in a single directory (possibly stored in a zip file) that contribute to a namespace package. Namespace packages today ======================== Python currently provides the pkgutil.extend_path to denote a package as a namespace package. The recommended way of using it is to put:: from pkgutil import extend_path __path__ = extend_path(__path__, __name__) int the package's ``__init__.py``. Every distribution needs to provide the same contents in its ``__init__.py``, so that extend_path is invoked independent of which portion of the package gets imported first. As a consequence, the package's ``__init__.py`` cannot practically define any names as it depends on the order of the package fragments on sys.path which portion is imported first. As a special feature, extend_path reads files named ``*.pkg`` which allow to declare additional portions. setuptools provides a similar function pkg_resources.declare_namespace that is used in the form:: import pkg_resources pkg_resources.declare_namespace(__name__) In the portion's __init__.py, no assignment to __path__ is necessary, as declare_namespace modifies the package __path__ through sys.modules. As a special feature, declare_namespace also supports zip files, and registers the package name internally so that future additions to sys.path by setuptools can properly add additional portions to each package. setuptools allows declaring namespace packages in a distribution's setup.py, so that distribution developers don't need to put the magic __path__ modification into __init__.py themselves. Rationale ========= The current imperative approach to namespace packages has lead to multiple slightly-incompatible mechanisms for providing namespace packages. For example, pkgutil supports ``*.pkg`` files; setuptools doesn't. Likewise, setuptools supports inspecting zip files, and supports adding portions to its _namespace_packages variable, whereas pkgutil doesn't. In addition, the current approach causes problems for system vendors. Vendor packages typically must not provide overlapping files, and an attempt to install a vendor package that has a file already on disk will fail or cause unpredictable behavior. As vendors might chose to package distributions such that they will end up all in a single directory for the namespace package, all portions would contribute conflicting __init__.py files. Specification ============= Rather than using an imperative mechanism for importing packages, a declarative approach is proposed here, as an extension to the existing ``*.pkg`` mechanism. The import statement is extended so that it directly considers ``*.pkg`` files during import; a directory is considered a package if it either contains a file named __init__.py, or a file whose name ends with ".pkg". In addition, the format of the ``*.pkg`` file is extended: a line with the single character ``*`` indicates that the entire sys.path will be searched for portions of the namespace package at the time the namespace packages is imported. Importing a package will immediately compute the package's __path__; the ``*.pkg`` files are not considered anymore after the initial import. If a ``*.pkg`` package contains an asterisk, this asterisk is prepended to the package's __path__ to indicate that the package is a namespace package (and that thus further extensions to sys.path might also want to extend __path__). At most one such asterisk gets prepended to the path. extend_path will be extended to recognize namespace packages according to this PEP, and avoid adding directories twice to __path__. No other change to the importing mechanism is made; searching modules (including __init__.py) will continue to stop at the first module encountered. Discussion ========== With the addition of ``*.pkg`` files to the import mechanism, namespace packages can stop filling out the namespace package's __init__.py. As a consequence, extend_path and declare_namespace become obsolete. It is recommended that distributions put a file <distribution>.pkg into their namespace packages, with a single asterisk. This allows vendor packages to install multiple portions of namespace package into a single directory, with no risk of overlapping files. Namespace packages can start providing non-trivial __init__.py implementations; to do so, it is recommended that a single distribution provides a portion with just the namespace package's __init__.py (and potentially other modules that belong to the namespace package proper). The mechanism is mostly compatible with the existing namespace mechanisms. extend_path will be adjusted to this specification; any other mechanism might cause portions to get added twice to __path__. Copyright ========= This document has been placed in the public domain. [View Less]

31 110

pthreads, fork, import, and execvp
by Rotem Yaari Sept. 16, 2009

Sept. 16, 2009

Hello everyone! We have been encountering several deadlocks in a threaded Python application which calls subprocess.Popen (i.e. fork()) in some of its threads. This has occurred on Python 2.4.1 on a 2.4.27 Linux kernel. Preliminary analysis of the hang shows that the child process blocks upon entering the execvp function, in which the import_lock is acquired due to the following line: def _ execvpe(file, args, env=None): from errno import ENOENT, ENOTDIR ... It is known that … [View More]

12 29

compiling python2.5 on linux under wine
by Luke Kenneth Casson Leighton Sept. 8, 2009

Sept. 8, 2009

hey, has anyone investigated compiling python2.5 using winegcc, under wine? i'm presently working my way through it, just for kicks, and was wondering if anyone would like to pitch in or stare at the mess under a microscope. it's not as crazed as it sounds. cross-compiling python2.5 for win32 with mingw32 is an absolute miserable bitch of a job that goes horribly wrong when you actually try to use the minimalist compiler to do any real work. so i figured that it would be easier to get python … [View More]compiled using wine. i _have_ got some success - a python script and a python.exe.so (which is winegcc's friendly way of telling you you have something that stands a chance of working) as well as a libpython25.dll.so. what i _don't_ yet have is an _md5.dll (or should it be _md5.lib?) i.e. the standard modules are a bit... iffy. the _winreg.o is compiled; the _md5.o is compiled; the winreg.lib is not. whoops. plus, it's necessary to enable nt_dl.c which is in PC/ _not_ in Modules/. one of the key issues that's a bit of a bitch is that python is compiled up for win32 with a hard-coded pyconfig.h which someone went to a _lot_ of trouble to create by hand instead of using autoconf. oh - and it uses visualstudio so there's not even a Makefile. ignoring that for the time-being was what allowed me to get as far as actually having a python interpreter (with no c-based modules). so there's a whole _stack_ of stuff that needs dragging kicking and screaming into the 21st century. there _is_ a reason why i want to do this. actually, there's two. firstly, i sure as shit do _not_ want to buy, download, install _or_ run visual studio. i flat-out refuse to run an MS os and visual studio runs like a dog under wine. secondly, i want a python25.lib which i can use to cross-compile modules for poor windows users _despite_ sticking to my principles and keeping my integrity as a free software developer. thirdly i'd like to cross-compile pywebkitgtk for win32 fourthly i'd like to compile and link applications to the extremely successful and well wicked MSHTML.DLL... in the _wine_ project :) not the one in windows (!) i want to experiment with DOM model manipulation - from python - similar to the OLPC HulaHop project - _but_ i want to compile or cross-compile everything from linux, not windows (see 1 above) fifthly i'd like to see COM (DCOM) working and pywin32 compiled and useable under wine, even if it means having to get a license to use dcom98 and oleauth.lib and oleauth.h etc. and all the developer files needed to link DCOM applications under windows. actually what i'd _really_ like to see is FreeDCE's DCOM work actually damn well finished, it's only been eight years since wez committed the first versions of the IDL and header files, and it's only been over fifteen years since microsoft began its world domination using COM and DCOM. ... but that's another story :) so that's ... five reasons not two. if anyone would like to collaborate on a crazed project with someone who can't count, i'm happy to make available what i've got up to so far, on github.org. l. [View Less]

6 12

GSoC: Core Python development tools
by Daniel (ajax) Diniz July 23, 2009

July 23, 2009

Hi, I'd like to bring up the general idea of using a PSF slot in GSoC2009 to improve the Python development infrastructure. I also happen to have two concrete proposals for that (such a coincidence!). But I assure you the general idea is more important than my proposals :) General: Solving issues that get in core devs' way when they work on Python development could be a nice PSF GSoC project. I believe there are enough code related tasks that would greatly improve Python development workflow … [View More]but lack manpower to complete. E.g., ISTM that a student working on svnmerge in past SoC editions would've been able to mitigate some painful shortcomings. If the core developers could come up with a list of peeves that would be solvable in code (in existing tools), that would allow for a very useful GSoC proposal. Proposals: These might fit the description above, and they're both tracker related (yep, one-trick-pony here). The upside is that at least one potential mentor is available for each, and I'd be able to offer support to the student. First, the PSF could invest a slot on integrating different tools of the development workflow. Variations of 'file issue at bug tracker, submit code for review' or 'branch locally to virtualenv, upload failing testcase to tracker, upload patch to tracker' command line utils. If these could be developed as general tools (i.e., not deeply tied to Python dev infrastructure), Ali Afshar from PIDA is willing to mentor it. I'd be available to help with Roundup and Rietveld (integration in progress), but would like to see it work with Launchpad, Bugzilla, Google Code and Review Board :) The other proposal is to use a slot in Roundup proper and the Python tracker instance. This could have a core Roundup developer as mentor, under the condition it's focused on Roundup itself. IMO, are some missing/broken core features in Roundup that would have a positive impact on our tracker, mostly those relating to searches, security and UI. I'd have a lot to contribute to the Python tracker part, based on ongoing work. Even if neither is considered worthy, I'll keep them on my to-do list and hope to slowly and hackishly work towards both proposals' goals. Barring feedback saying that they're out of scope, stupid and downright offensive, I'll post details on each to this thread very soon. So, if the PSF was to use a slot on improving the way you work on Python development, what would you like to see fixed or implemented? Best regards, Daniel [View Less]

13 31

Re: subprocess and EINTR errnos
by Peter Astrand July 6, 2009

July 6, 2009

On Wed, 10 Nov 2004, John P Speno wrote: Hi, sorry for the delayed response. > While using subprocess (aka popen5), I came across one potential gotcha. I've had > exceptions ending like this: > > File "test.py", line 5, in test > cmd = popen5.Popen(args, stdout=PIPE) > File "popen5.py", line 577, in __init__ > data = os.read(errpipe_read, 1048576) # Exceptions limited to 1 MB > OSError: [Errno 4] Interrupted system call > > (on Solaris 9) > > … [View More]Would it make sense for subprocess to use a more robust read() function > which can handle these cases, i.e. when the parent's read on the pipe > to the child's stderr is interrupted by a system call, and returns EINTR? > I imagine it could catch EINTR and EAGAIN and retry the failed read(). I assume you are using signals in your application? The os.read above is not the only system call that can fail with EINTR. subprocess.py is full of other system calls that can fail, and I suspect that many other Python modules are as well. I've made a patch (attached) to subprocess.py (and test_subprocess.py) that should guard against EINTR, but I haven't committed it yet. It's quite large. Are Python modules supposed to handle EINTR? Why not let the C code handle this? Or, perhaps the signal module should provide a sigaction function, so that users can use SA_RESTART. Index: subprocess.py =================================================================== RCS file: /cvsroot/python/python/dist/src/Lib/subprocess.py,v retrieving revision 1.8 diff -u -r1.8 subprocess.py --- subprocess.py 7 Nov 2004 14:30:34 -0000 1.8 +++ subprocess.py 17 Nov 2004 19:42:30 -0000 @@ -888,6 +888,50 @@ pass + def _read_no_intr(self, fd, buffersize): + """Like os.read, but retries on EINTR""" + while True: + try: + return os.read(fd, buffersize) + except OSError, e: + if e.errno == errno.EINTR: + continue + else: + raise + + + def _read_all(self, fd, buffersize): + """Like os.read, but retries on EINTR, and reads until EOF""" + all = "" + while True: + data = self._read_no_intr(fd, buffersize) + all += data + if data == "": + return all + + + def _write_no_intr(self, fd, s): + """Like os.write, but retries on EINTR""" + while True: + try: + return os.write(fd, s) + except OSError, e: + if e.errno == errno.EINTR: + continue + else: + raise + + def _waitpid_no_intr(self, pid, options): + """Like os.waitpid, but retries on EINTR""" + while True: + try: + return os.waitpid(pid, options) + except OSError, e: + if e.errno == errno.EINTR: + continue + else: + raise + def _execute_child(self, args, executable, preexec_fn, close_fds, cwd, env, universal_newlines, startupinfo, creationflags, shell, @@ -963,7 +1007,7 @@ exc_value, tb) exc_value.child_traceback = ''.join(exc_lines) - os.write(errpipe_write, pickle.dumps(exc_value)) + self._write_no_intr(errpipe_write, pickle.dumps(exc_value)) # This exitcode won't be reported to applications, so it # really doesn't matter what we return. @@ -979,7 +1023,7 @@ os.close(errwrite) # Wait for exec to fail or succeed; possibly raising exception - data = os.read(errpipe_read, 1048576) # Exceptions limited to 1 MB + data = self._read_all(errpipe_read, 1048576) # Exceptions limited to 1 MB os.close(errpipe_read) if data != "": child_exception = pickle.loads(data) @@ -1003,7 +1047,7 @@ attribute.""" if self.returncode == None: try: - pid, sts = os.waitpid(self.pid, os.WNOHANG) + pid, sts = self._waitpid_no_intr(self.pid, os.WNOHANG) if pid == self.pid: self._handle_exitstatus(sts) except os.error: @@ -1015,7 +1059,7 @@ """Wait for child process to terminate. Returns returncode attribute.""" if self.returncode == None: - pid, sts = os.waitpid(self.pid, 0) + pid, sts = self._waitpid_no_intr(self.pid, 0) self._handle_exitstatus(sts) return self.returncode @@ -1049,27 +1093,33 @@ stderr = [] while read_set or write_set: - rlist, wlist, xlist = select.select(read_set, write_set, []) + try: + rlist, wlist, xlist = select.select(read_set, write_set, []) + except select.error, e: + if e[0] == errno.EINTR: + continue + else: + raise if self.stdin in wlist: # When select has indicated that the file is writable, # we can write up to PIPE_BUF bytes without risk # blocking. POSIX defines PIPE_BUF >= 512 - bytes_written = os.write(self.stdin.fileno(), input[:512]) + bytes_written = self._write_no_intr(self.stdin.fileno(), input[:512]) input = input[bytes_written:] if not input: self.stdin.close() write_set.remove(self.stdin) if self.stdout in rlist: - data = os.read(self.stdout.fileno(), 1024) + data = self._read_no_intr(self.stdout.fileno(), 1024) if data == "": self.stdout.close() read_set.remove(self.stdout) stdout.append(data) if self.stderr in rlist: - data = os.read(self.stderr.fileno(), 1024) + data = self._read_no_intr(self.stderr.fileno(), 1024) if data == "": self.stderr.close() read_set.remove(self.stderr) Index: test/test_subprocess.py =================================================================== RCS file: /cvsroot/python/python/dist/src/Lib/test/test_subprocess.py,v retrieving revision 1.14 diff -u -r1.14 test_subprocess.py --- test/test_subprocess.py 12 Nov 2004 15:51:48 -0000 1.14 +++ test/test_subprocess.py 17 Nov 2004 19:42:30 -0000 @@ -7,6 +7,7 @@ import tempfile import time import re +import errno mswindows = (sys.platform == "win32") @@ -35,6 +36,16 @@ fname = tempfile.mktemp() return os.open(fname, os.O_RDWR|os.O_CREAT), fname + def read_no_intr(self, obj): + while True: + try: + return obj.read() + except IOError, e: + if e.errno == errno.EINTR: + continue + else: + raise + # # Generic tests # @@ -123,7 +134,7 @@ p = subprocess.Popen([sys.executable, "-c", 'import sys; sys.stdout.write("orange")'], stdout=subprocess.PIPE) - self.assertEqual(p.stdout.read(), "orange") + self.assertEqual(self.read_no_intr(p.stdout), "orange") def test_stdout_filedes(self): # stdout is set to open file descriptor @@ -151,7 +162,7 @@ p = subprocess.Popen([sys.executable, "-c", 'import sys; sys.stderr.write("strawberry")'], stderr=subprocess.PIPE) - self.assertEqual(remove_stderr_debug_decorations(p.stderr.read()), + self.assertEqual(remove_stderr_debug_decorations(self.read_no_intr(p.stderr)), "strawberry") def test_stderr_filedes(self): @@ -186,7 +197,7 @@ 'sys.stderr.write("orange")'], stdout=subprocess.PIPE, stderr=subprocess.STDOUT) - output = p.stdout.read() + output = self.read_no_intr(p.stdout) stripped = remove_stderr_debug_decorations(output) self.assertEqual(stripped, "appleorange") @@ -220,7 +231,7 @@ stdout=subprocess.PIPE, cwd=tmpdir) normcase = os.path.normcase - self.assertEqual(normcase(p.stdout.read()), normcase(tmpdir)) + self.assertEqual(normcase(self.read_no_intr(p.stdout)), normcase(tmpdir)) def test_env(self): newenv = os.environ.copy() @@ -230,7 +241,7 @@ 'sys.stdout.write(os.getenv("FRUIT"))'], stdout=subprocess.PIPE, env=newenv) - self.assertEqual(p.stdout.read(), "orange") + self.assertEqual(self.read_no_intr(p.stdout), "orange") def test_communicate(self): p = subprocess.Popen([sys.executable, "-c", @@ -305,7 +316,8 @@ 'sys.stdout.write("\\nline6");'], stdout=subprocess.PIPE, universal_newlines=1) - stdout = p.stdout.read() + + stdout = self.read_no_intr(p.stdout) if hasattr(open, 'newlines'): # Interpreter with universal newline support self.assertEqual(stdout, @@ -343,7 +355,7 @@ def test_no_leaking(self): # Make sure we leak no resources - max_handles = 1026 # too much for most UNIX systems + max_handles = 10 # too much for most UNIX systems if mswindows: max_handles = 65 # a full test is too slow on Windows for i in range(max_handles): @@ -424,7 +436,7 @@ 'sys.stdout.write(os.getenv("FRUIT"))'], stdout=subprocess.PIPE, preexec_fn=lambda: os.putenv("FRUIT", "apple")) - self.assertEqual(p.stdout.read(), "apple") + self.assertEqual(self.read_no_intr(p.stdout), "apple") def test_args_string(self): # args is a string @@ -457,7 +469,7 @@ p = subprocess.Popen(["echo $FRUIT"], shell=1, stdout=subprocess.PIPE, env=newenv) - self.assertEqual(p.stdout.read().strip(), "apple") + self.assertEqual(self.read_no_intr(p.stdout).strip(), "apple") def test_shell_string(self): # Run command through the shell (string) @@ -466,7 +478,7 @@ p = subprocess.Popen("echo $FRUIT", shell=1, stdout=subprocess.PIPE, env=newenv) - self.assertEqual(p.stdout.read().strip(), "apple") + self.assertEqual(self.read_no_intr(p.stdout).strip(), "apple") def test_call_string(self): # call() function with string argument on UNIX @@ -525,7 +537,7 @@ p = subprocess.Popen(["set"], shell=1, stdout=subprocess.PIPE, env=newenv) - self.assertNotEqual(p.stdout.read().find("physalis"), -1) + self.assertNotEqual(self.read_no_intr(p.stdout).find("physalis"), -1) def test_shell_string(self): # Run command through the shell (string) @@ -534,7 +546,7 @@ p = subprocess.Popen("set", shell=1, stdout=subprocess.PIPE, env=newenv) - self.assertNotEqual(p.stdout.read().find("physalis"), -1) + self.assertNotEqual(self.read_no_intr(p.stdout).find("physalis"), -1) def test_call_string(self): # call() function with string argument on Windows /Peter Åstrand <astrand(a)lysator.liu.se> [View Less]

5 5

Indentation oddness...
by Dino Viehland June 1, 2009

June 1, 2009

Consider the code: code = "def Foo():\n\n pass\n\n " This code is malformed in that the final indentation (2 spaces) does not agree with the previous indentation of the pass statement (4 spaces). Or maybe it's just fine if you take the blank lines should be ignored statement from the docs to be true. So let's look at different ways I can consume this code. If I use compile to compile this: compile(code, 'foo', 'single') I get an IndentationError: unindent does not match any outer … [View More]

4 6

Re: [Python-Dev] Survey on DVCS usage and experience
by Senthil Kumaran May 31, 2009

May 31, 2009

On Wed, May 27, 2009 at 06:02:57PM -0600, Brian de Alwis wrote: > With Python having recently chosen to switch to Mercurial, I hoped > that any developers who've used a DVCS (and who are over 18 years > old) might like to participate in our survey and share your Just curious. Why is this age restriction? You might miss out few key developers... -- Senthil

5 4

[Sphinx] GSoC project announcement
by Wojciech Walczak May 30, 2009

May 30, 2009

Hi, guys, just a short introduction of one of this year's GSoC PSF projects: I am implementing a support for per-paragraph comments and user/developer interface for submitting/committing fixes in Sphinx[1]. In case you are interesed in adding your 2 cents (or more) by commenting on my application[2] or proposing some enhancements - feel free to do so on sphinx-dev[3]. Or take a look at my blog to keep up to date[4]. [1] - http://sphinx.pocoo.org/ [2] - http://tosh.pl/gminick/gsoc/sphinx/ … [View More]

1 0

cleanup before 3.1 is released
by Neal Norwitz May 30, 2009

May 30, 2009

Has anyone run valgrind/purify and pychecker/pylint on the 3.1 code recently? Both sets of tools should be used before the final release so we can fix any obvious problems. n

2 1

[RELEASED] Python 3.1 Release Candidate 1
by Benjamin Peterson May 30, 2009

May 30, 2009

On behalf of the Python development team, I'm happy to announce the first release candidate of Python 3.1. Python 3.1 focuses on the stabilization and optimization of the features and changes that Python 3.0 introduced. For example, the new I/O system has been rewritten in C for speed. File system APIs that use unicode strings now handle paths with undecodable bytes in them. Other features include an ordered dictionary implementation, a condensed syntax for nested with statements, and … [View More]

1 0

looking for some people to talk with about Python development
by carmstr3＠illinois.edu May 30, 2009

May 30, 2009

Hello, My name is Chandler Armstrong and I'm investigating environments of collaboration. I'm a PhD candidate at the University of Illinois, Urbana-Champaign, specialized in internet research and science & technology studies. I'm generally interested in development methods overall, and specifically interested in both artificial languange construction and evolution, and collaboration in open-source models. I would like to talk to some members of the Python development community about … [View More]what kinds of activities they do within it. If anybody is interested in this please email me at carmstr3(a)illinois.edu. I will send you a document that describes the research and interview in more detail. I'd like to do a voice interview over skype or a phone, but I can accomodate an online chat or even email. I have some current research on this specific mailing list which is more quantitative in nature. I downloaded the entire mailing list from the archives. Next I looked through all the python-dev summaries and used links provided to referenced threads to indicate that a particular message or thread was meaningful in development. I characterized the mailing list as threads, and each instance with about 30 attributes (things like the number of posts, the depth of the tree, a measure of 'branchyness' of the thread, the standard deviation of post counts across posters, the hour/day/month of the thread, etc). Using these attributes I attempted to classify, using logistic regression, the threads that were indicated as meaningful in the python-dev summaries. There are some significant results. If anyone is interested I can send you my results, or even post them here to the list. I'll be presenting my results at the Classification Society Conference at St. Louis in June. The ! wo! rk is unpublished at the moment but I hope to find a journal for it this summer. I used entirely Python for all that quantitative work: downloading the mailing list and going through all the summaries, opening the links and matching the referenced message to the correct one in my downloaded database, and cleaning and transforming data. It was a ton of fun. I hope to develop more scripts for other sorts of automated analysis. At any rate, please contact me if you'de like to contribute to my current tack of investigation. I would ultimately want to interview however many people that are willing to talk with me. I need to do about two in the next couple of weeks, and I would get with other volunteers in the weeks after that. Thanks, Chandler Armstrong carmstr3(a)illinois.edu [View Less]

1 0

Indentation oddness...
by Dino Viehland May 30, 2009

May 30, 2009

Consider the code: code = "def Foo():\n\n pass\n\n " This code is malformed in that the final indentation (2 spaces) does not agree with the previous indentation of the pass statement (4 spaces). Or maybe it's just fine if you take the blank lines should be ignored statement from the docs to be true. So let's look at different ways I can consume this code. If I use compile to compile this: compile(code, 'foo', 'single') I get an IndentationError: unindent does not match any outer … [View More]

1 0

Summary of Python tracker Issues
by Python tracker May 29, 2009

May 29, 2009

ACTIVITY SUMMARY (05/22/09 - 05/29/09) Python tracker at http://bugs.python.org/ To view or respond to any of the issues listed below, click on the issue number. Do NOT respond to this message. 2201 open (+36) / 15764 closed (+18) / 17965 total (+54) Open issues with patches: 866 Average duration of open issues: 652 days. Median duration of open issues: 400 days. Open Issues Breakdown open 2175 (+36) pending 26 ( +0) Issues Created Or Reopened (55) … [View More]

1 0

Possibility of binary configuration mismatch
by David Abrahams May 29, 2009

May 29, 2009

Hi All, I'm not sure there's anything you can do about this, but I thought I should alert the Python devs that it can happen... http://allmydata.org/trac/tahoe/ticket/704#comment:7 describes a situation where my macports-installed python25 had a pyOpenSSL egg installed in it by something other than macports (possibly by easy_install-2.5?) that was not compatible with the Python build. My hunch is that the pyOpenSSL had binaries compiled against a UCS4 Python, but I don't know for sure. … [View More]

2 1

Warnings when no file exists.
by Campbell Barton May 29, 2009

May 29, 2009

Hi, there has been a problem in blender3d for 6~ years or so thats eluded me, I decided to look into today. - Whenever the a script raises a warnings python prints out binary garbage in the console. Some users complain when they run python games in blender they get beeps coming from the PC speaker. It turns out that _warning.c's setup_context() is taking the first value of argv (line 534 in 2.6.2), which in our case is the blender binary. then some part of the binary is printed to the console.… [View More]

1 0

C/Python API Index removed?
by Campbell Barton May 29, 2009

May 29, 2009

This page used to give an index of the C/Python API functions too http://docs.python.org/genindex-all.html But a week or so ago I noticed all these functions are now missing (I remember they existed in 2.6.1 docs) Was this intentional? Quite a while ago, ~2.5 the C/API docs had their own index which personally I prefer. http://docs.python.org/c-api/index.html This page is called an index but Im looking for a page like http://docs.python.org/genindex-all.html which includes all C/API … [View More]

1 0

question about docstring formatting
by Jeremy Hylton May 29, 2009

May 29, 2009

A question came up at work about docstring formatting. It relates to the description of the summary line in PEP 257. http://www.python.org/dev/peps/pep-0257/ """Multi-line docstrings consist of a summary line just like a one-line docstring, followed by a blank line, followed by a more elaborate description. The summary line may be used by automatic indexing tools; it is important that it fits on one line and is separated from the rest of the docstring by a blank line. The summary line may be … [View More]

6 5

[buildbot] some build slaves in bad shape
by Tarek Ziadé May 28, 2009

May 28, 2009

Hello, I've noticed some problems since this morning with the trunk and 3.x stable buildbots: - x86 XP-4 (trunk and 3x) is throwing an "no space left on device" error when it compiles the sqlite module in its temp dir - amd64 gentoo 3.x and ia64 Ubuntu 3.x buildbot versions seem to be too old to run, they should be upgraded - ppc Debian unstable trunk keeps on failing to connect to svn.python.org Regards Tarek -- Tarek Ziadé | http://ziade.org

2 3

Re: [Python-Dev] [Python-checkins] r72995 - in python/branches/py3k: Doc/library/contextlib.rst Doc/whatsnew/3.1.rst Lib/contextlib.py Lib/test/test_contextlib.py Misc/NEWS
by Eric Smith May 28, 2009

May 28, 2009

raymond.hettinger wrote: > Author: raymond.hettinger > Date: Fri May 29 00:20:03 2009 > New Revision: 72995 > > Log: > Deprecate contextlib.nested(). The with-statement now provides this functionality directly. > > Modified: > python/branches/py3k/Doc/library/contextlib.rst > python/branches/py3k/Doc/whatsnew/3.1.rst > python/branches/py3k/Lib/contextlib.py > python/branches/py3k/Lib/test/test_contextlib.py > python/branches/py3k/Misc/… [View More]

1 0

Making the GIL faster & lighter on Windows
by Phillip Sitbon May 28, 2009

May 28, 2009

Hi everyone, I'm new to the list but I've been embedding Python and working very closely with the core sources for many years now. I discovered Python a long time ago when I needed to embed a scripting language and found the PHP sources... unreadable ;) Anyway, I'd like to ask something that may have been asked already, so I apologize if this has been covered. Instead of removing the GIL, has anyone thought of making it more lightweight? The current situation for Windows is that the single-… [View More]thread case is decently fast (via interlocked operations), but it drops to using an event object in the case of contention. (see thread_nt.h) Now, I don't have any specific evidence aside from my experience in Windows multithreaded programming, but event objects are often considered the slowest synchronization mechanism available. So, what are the alternatives? Mutexes or critical sections. Semaphores too, if you want to get fancy, but I digress. Because mutexes have the capability of inter-process locking, which we don't need, critical sections fit the bill as a lightweight locking mechanism. They work in a way similar to how the Python GIL is handled: first, attempt an interlocked operation, and if another thread owns the lock, wait on a kernel object. They are known to be extremely fast. There are some catches with using a critical section instead of the current method: 1. It is recursive, while the current GIL setup is not. Would it break Python to support (or deal with) recursive behavior at the GIL level? Note that we can still disallow recursion and fail because we know if the current thread is the lock owner, but the return from the lock function is usually only checked when the wait parameter is zero (meaning "don't block, just try to acquire"). The biggest problem I see here is how mixing the PyGILState_* API with multiple interpreters will behave: when PyGILState_Ensure() is called while the GIL is held for a thread state under an interpreter other than the main interpreter, it tries to re-lock the GIL. This would normally cause a deadlock, but the best we could do with a critical section is have the call fail and/or increase a recursion counter. If maintaining behavior is absolutely necessary, I guess it would be pretty easy to force a deadlock. Personally, I would prefer a Py_FatalError or something like it. 2. Backwards incompatibility: TryEnterCriticalSection isn't available pre-NT4, so Windows 95 support is broken. Microsoft doesn't support or even mention it in the list of supporting OSes for their API functions anymore, so... non-issue? Some of the data structure is available to us, so I bet it would be easy to implement the function manually. 3. ?? - I'm sure there are other issues that deserve a look. I've given this a shot already while doing some concurrency testing with my ISAPI extension (PyISAPIe). First of all, nothing looks broken yet. I'm using my modified python26.dll to run all of my Python code and trying to find anywhere it could possibly break. For multiple concurrent requests against a single multithreaded ISAPI handler process, I see a statistically significant speed increase depending on how much Python code is executed. With more Python code executed (e.g. a Django page), the speedup was about 2x. I haven't tested with varied values for _Py_CheckInterval aside from finding a sweet spot for my specific purposes, but using 100 (the default) would likely make the performance difference more noticeable. A spin mutex also does well, but the results vary a lot more. Just as a disclaimer, my tests were nowhere near scientific, but if anyone needs convincing I can come up with some actual measurements. I think at this point most of you are wondering more about what it would break. Hopefully I haven't wasted anyone's time - I just wanted to share what I see as a possibly substantial improvement to Python's core. let me know if you're interested in a patch to use for your own testing. Cheers, Phillip [View Less]

8 16

Survey on DVCS usage and experience
by Brian de Alwis May 28, 2009

May 28, 2009

Hello everybody. I'm Brett's former lab-mate, and am part of a team conducting a survey to understand the perceived benefits and challenges of using a decentralized or distributed version control systems (DVCS) in software development. With Python having recently chosen to switch to Mercurial, I hoped that any developers who've used a DVCS (and who are over 18 years old) might like to participate in our survey and share your experiences. (We followed your extensive discussions on the switch … [View More]

1 0

Arguments of MatchObject in re module
by MRAB May 27, 2009

May 27, 2009

I've just noticed an oddity of the re module while looking at the sources. I'll illustrate it below: >>> import re >>> p = re.compile("foo") >>> help(p.match) Help on built-in function match: match(...) match(string[, pos[, endpos]]) --> match object or None. Matches zero or more characters at the beginning of the string >>> p.match(string="foo") Traceback (most recent call last): File "<pyshell#8>", line 1, in <module> … [View More]

2 1

PEP 384: Defining a Stable ABI
by "Martin v. Löwis" May 27, 2009

May 27, 2009

Thomas Wouters reminded me of a long-standing idea; I finally found the time to write it down. Please comment! Regards, Martin PEP: 384 Title: Defining a Stable ABI Version: $Revision: 72754 $ Last-Modified: $Date: 2009-05-17 21:14:52 +0200 (So, 17. Mai 2009) $ Author: Martin v. Löwis <martin(a)v.loewis.de> Status: Draft Type: Standards Track Content-Type: text/x-rst Created: 17-May-2009 Python-Version: 3.2 Post-History: Abstract ======== Currently, each feature release introduces a … [View More]new name for the Python DLL on Windows, and may cause incompatibilities for extension modules on Unix. This PEP proposes to define a stable set of API functions which are guaranteed to be available for the lifetime of Python 3, and which will also remain binary-compatible across versions. Extension modules and applications embedding Python can work with different feature releases as long as they restrict themselves to this stable ABI. Rationale ========= The primary source of ABI incompatibility are changes to the lay-out of in-memory structures. For example, the way in which string interning works, or the data type used to represent the size of an object, have changed during the life of Python 2.x. As a consequence, extension modules making direct access to fields of strings, lists, or tuples, would break if their code is loaded into a newer version of the interpreter without recompilation: offsets of other fields may have changed, making the extension modules access the wrong data. In some cases, the incompatibilities only affect internal objects of the interpreter, such as frame or code objects. For example, the way line numbers are represented has changed in the 2.x lifetime, as has the way in which local variables are stored (due to the introduction of closures). Even though most applications probably never used these objects, changing them had required to change the PYTHON_API_VERSION. On Linux, changes to the ABI are often not much of a problem: the system will provide a default Python installation, and many extension modules are already provided pre-compiled for that version. If additional modules are needed, or additional Python versions, users can typically compile them themselves on the system, resulting in modules that use the right ABI. On Windows, multiple simultaneous installations of different Python versions are common, and extension modules are compiled by their authors, not by end users. To reduce the risk of ABI incompatibilities, Python currently introduces a new DLL name pythonXY.dll for each feature release, whether or not ABI incompatibilities actually exist. With this PEP, it will be possible to reduce the dependency of binary extension modules on a specific Python feature release, and applications embedding Python can be made work with different releases. Specification ============= The ABI specification falls into two parts: an API specification, specifying what function (groups) are available for use with the ABI, and a linkage specification specifying what libraries to link with. The actual ABI (layout of structures in memory, function calling conventions) is not specified, but implied by the compiler. As a recommendation, a specific ABI is recommended for selected platforms. During evolution of Python, new ABI functions will be added. Applications using them will then have a requirement on a minimum version of Python; this PEP provides no mechanism for such applications to fall back when the Python library is too old. Terminology ----------- Applications and extension modules that want to use this ABI are collectively referred to as "applications" from here on. Header Files and Preprocessor Definitions ----------------------------------------- Applications shall only include the header file Python.h (before including any system headers), or, optionally, include pyconfig.h, and then Python.h. During the compilation of applications, the preprocessor macro Py_LIMITED_API must be defined. Doing so will hide all definitions that are not part of the ABI. Structures ---------- Only the following structures and structure fields are accessible to applications: - PyObject (ob_refcnt, ob_type) - PyVarObject (ob_base, ob_size) - Py_buffer (buf, obj, len, itemsize, readonly, ndim, shape, strides, suboffsets, smalltable, internal) - PyMethodDef (ml_name, ml_meth, ml_flags, ml_doc) - PyMemberDef (name, type, offset, flags, doc) - PyGetSetDef (name, get, set, doc, closure) The accessor macros to these fields (Py_REFCNT, Py_TYPE, Py_SIZE) are also available to applications. The following types are available, but opaque (i.e. incomplete): - PyThreadState - PyInterpreterState Type Objects ------------ The structure of type objects is not available to applications; declaration of "static" type objects is not possible anymore (for applications using this ABI). Instead, type objects get created dynamically. To allow an easy creation of types (in particular, to be able to fill out function pointers easily), the following structures and functions are available:: typedef struct{ int slot; /* slot id, see below */ void *pfunc; /* function pointer */ } PyType_Slot; struct{ const char* name; const char* doc; int basicsize; int itemsize; int flags; PyType_Slot *slots; /* terminated by slot==0. */ } PyType_Spec; PyObject* PyType_FromSpec(PyType_Spec*); To specify a slot, a unique slot id must be provided. New Python versions may introduce new slot ids, but slot ids will never be recycled. Slots may get deprecated, but continue to be supported throughout Python 3.x. The slot ids are named like the field names of the structures that hold the pointers in Python 3.1, with an added ``Py_`` prefix (i.e. Py_tp_dealloc instead of just tp_dealloc): - tp_dealloc, tp_print, tp_getattr, tp_setattr, tp_repr, tp_hash, tp_call, tp_str, tp_getattro, tp_setattro, tp_doc, tp_traverse, tp_clear, tp_richcompare, tp_iter, tp_iternext, tp_methods, tp_base, tp_descr_set, tp_descr_set, tp_init, tp_alloc, tp_new, tp_is_gc, tp_bases, tp_del - nb_add nb_subtract nb_multiply nb_remainder nb_divmod nb_power nb_negative nb_positive nb_absolute nb_bool nb_invert nb_lshift nb_rshift nb_and nb_xor nb_or nb_int nb_float nb_inplace_add nb_inplace_subtract nb_inplace_multiply nb_inplace_remainder nb_inplace_power nb_inplace_lshift nb_inplace_rshift nb_inplace_and nb_inplace_xor nb_inplace_or nb_floor_divide nb_true_divide nb_inplace_floor_divide nb_inplace_true_divide nb_index - sq_length sq_concat sq_repeat sq_item sq_ass_item was_sq_ass_slice sq_contains sq_inplace_concat sq_inplace_repeat - mp_length mp_subscript mp_ass_subscript - bf_getbuffer bf_releasebuffer XXX Not supported yet: tp_weaklistoffset, tp_dictoffset The following fields cannot be set during type definition: - tp_dict tp_mro tp_cache tp_subclasses tp_weaklist Functions and function-like Macros ---------------------------------- All functions starting with _Py are not available to applications. Also, all functions that expect parameter types that are unavailable to applications are excluded from the ABI, such as PyAST_FromNode (which expects a ``node*``). All other functions are available, unless excluded below. Function-like macros (in particular, field access macros) remain available to applications, but get replaced by function calls (unless their definition only refers to features of the ABI, such as the various _Check macros) ABI function declarations will not change their parameters or return types. If a change to the signature becomes necessary, a new function will be introduced. If the new function is source-compatible (e.g. if just the return type changes), an alias macro may get added to redirect calls to the new function when the applications is recompiled. If continued provision of the old function is not possible, it may get deprecated, then removed, in accordance with PEP 7, causing applications that use that function to break. Excluded Functions ------------------ Functions declared in the following header files are not part of the ABI: - cellobject.h - classobject.h - code.h - frameobject.h - funcobject.h - genobject.h - pyarena.h - pydebug.h - symtable.h - token.h - traceback.h Global Variables ---------------- Global variables representing types and exceptions are available to applications. XXX provide a complete list. XXX should restrict list of globals to truly "builtin" stuff, excluding everything that can also be looked up through imports. XXX may specify access to predefined types and exceptions through the interpreter state, with appropriate Get macros. Other Macros ------------ All macros defining symbolic constants are available to applications; the numeric values will not change. In addition, the following macros are available: - Py_BEGIN_ALLOW_THREADS, Py_BLOCK_THREADS, Py_UNBLOCK_THREADS, Py_END_ALLOW_THREADS Linkage ------- On Windows, applications shall link with python3.dll; an import library python3.lib will be available. This DLL will redirect all of its API functions through /export linker options to the full interpreter DLL, i.e. python3y.dll. XXX is it possible to redirect global variables in the same way? If not, python3.dll would have to copy them, and we should verify that all available global variables are read-only. On Unix systems, the ABI is typically provided by the python executable itself. PyModule_Create is changed to pass ``3`` as the API version if the extension module was compiled with Py_LIMITED_API; the version check for the API version will accept either 3 or the current PYTHON_API_VERSION as conforming. If Python is compiled as a shared library, it is installed as both libpython3.so, and libpython3.y.so; applications conforming to this PEP should then link to the former. XXX is it possible to make the soname libpython.so.3, and still have some applications link to libpython3.y.so? Implementation Strategy ======================= This PEP will be implemented in a branch, allowing users to check whether their modules conform to the ABI. To simplify this testing, an additional macro Py_LIMITED_API_WITH_TYPES will expose the existing type object layout, to let users postpone rewriting all types. When the this branch is merged into the 3.2 code base, this macro will be removed. Copyright ========= This document has been placed in the public domain. [View Less]

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