Mailman 3 সেপ্টেম্বর 2004 - Python-Dev

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

18 মে, 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

unicode inconsistency?
by Neil Schemenauer 9 মার্চ, 2005

9 মার্চ, 2005

Perhaps this is more approprate for python-list but I looks like a bug to me. Example code: class A: def __str__(self): return u'\u1234' '%s' % u'\u1234' # this works '%s' % A() # this doesn't work It will work if 'A' subclasses from 'unicode' but should not be necessary, IMHO. Any reason why this shouldn't be fixed? Neil

6 15

RE: [Python-Dev] Those import related syntax errors again...
by Samuele Pedroni 23 ফেব্রুয়ারি, 2005

23 ফেব্রুয়ারি, 2005

Hi. [Mark Hammond] > The point isn't about my suffering as such. The point is more that > python-dev owns a tiny amount of the code out there, and I don't believe we > should put Python's users through this. > > Sure - I would be happy to "upgrade" all the win32all code, no problem. I > am also happy to live in the bleeding edge and take some pain that will > cause. > > The issue is simply the user base, and giving Python a reputation of not > being able to painlessly upgrade even dot revisions. I agree with all this. [As I imagined explicit syntax did not catch up and would require lot of discussions.] [GvR] > > Another way is to use special rules > > (similar to those for class defs), e.g. having > > > > <frag> > > y=3 > > def f(): > > exec "y=2" > > def g(): > > return y > > return g() > > > > print f() > > </frag> > > > > # print 3. > > > > Is that confusing for users? maybe they will more naturally expect 2 > > as outcome (given nested scopes). > > This seems the best compromise to me. It will lead to the least > broken code, because this is the behavior that we had before nested > scopes! It is also quite easy to implement given the current > implementation, I believe. > > Maybe we could introduce a warning rather than an error for this > situation though, because even if this behavior is clearly documented, > it will still be confusing to some, so it is better if we outlaw it in > some future version. > Yes this can be easy to implement but more confusing situations can arise: <frag> y=3 def f(): y=9 exec "y=2" def g(): return y return y,g() print f() </frag> What should this print? the situation leads not to a canonical solution as class def scopes. or <frag> def f(): from foo import * def g(): return y return g() print f() </frag> [Mark Hammond] > > This probably won't be a very popular suggestion, but how about pulling > > nested scopes (I assume they are at the root of the problem) > > until this can be solved cleanly? > > Agreed. While I think nested scopes are kinda cool, I have lived without > them, and really without missing them, for years. At the moment the cure > appears worse then the symptoms in at least a few cases. If nothing else, > it compromises the elegant simplicity of Python that drew me here in the > first place! > > Assuming that people really _do_ want this feature, IMO the bar should be > raised so there are _zero_ backward compatibility issues. I don't say anything about pulling nested scopes (I don't think my opinion can change things in this respect) but I should insist that without explicit syntax IMO raising the bar has a too high impl cost (both performance and complexity) or creates confusion. [Andrew Kuchling] > >Assuming that people really _do_ want this feature, IMO the bar should be > >raised so there are _zero_ backward compatibility issues. > > Even at the cost of additional implementation complexity? At the cost > of having to learn "scopes are nested, unless you do these two things > in which case they're not"? > > Let's not waffle. If nested scopes are worth doing, they're worth > breaking code. Either leave exec and from..import illegal, or back > out nested scopes, or think of some better solution, but let's not > introduce complicated backward compatibility hacks. IMO breaking code would be ok if we issue warnings today and implement nested scopes issuing errors tomorrow. But this is simply a statement about principles and raised impression. IMO import * in an inner scope should end up being an error, not sure about 'exec's. We will need a final BDFL statement. regards, Samuele Pedroni.

18 78

mimetypes and _winreg
by Mike Brown 2 ফেব্রুয়ারি, 2005

2 ফেব্রুয়ারি, 2005

I thought it would be nice to try to improve the mimetypes module by having it, on Windows, query the Registry to get the mapping of filename extensions to media types, since the mimetypes code currently just blindly checks posix-specific paths for httpd-style mapping files. However, it seems that the way to get mappings from the Windows registry is excessively slow in Python. I'm told that the reason has to do with the limited subset of APIs that are exposed in the _winreg module. I think it is that EnumKey(key, index) is querying for the entire list of subkeys for the given key every time you call it. Or something. Whatever the situation is, the code I tried below is way slower than I think it ought to be. Does anyone have any suggestions (besides "write it in C")? Could _winreg possibly be improved to provide an iterator or better interface to get the subkeys? (or certain ones? There are a lot of keys under HKEY_CLASSES_ROOT, and I only need the ones that start with a period). Should I file this as a feature request? Thanks -Mike from _winreg import HKEY_CLASSES_ROOT, OpenKey, EnumKey, QueryValueEx i = 0 typemap = {} try: while 1: subkeyname = EnumKey(HKEY_CLASSES_ROOT, i) try: subkey = OpenKey(HKEY_CLASSES_ROOT, subkeyname) if subkeyname[:1] == '.': data = QueryValueEx(subkey, 'Content Type')[0] print subkeyname, '=', data typemap[subkeyname] = data # data will be unicode except EnvironmentError, WindowsError: pass i += 1 except WindowsError: pass

3 4

assert failure on obmalloc
by Jeremy Hylton 10 অক্টোবর, 2004

10 অক্টোবর, 2004

Failure running the test suite today with -u compiler enabled on Windows XP. test_logging Assertion failed: bp != NULL, file \code\python\dist\src\Objects\obmalloc.c, line 604 The debugger says the error is here: msvcr71d.dll!_assert(const char * expr=0x1e22bcc0, const char * filename=0x1e22bc94, unsigned int lineno=604) Line 306 C python24_d.dll!PyObject_Malloc(unsigned int nbytes=100) Line 604 + 0x1b C python24_d.dll!_PyObject_DebugMalloc(unsigned int nbytes=84) Line 1014 + 0x9 C python24_d.dll!PyThreadState_New(_is * interp=0x00951028) Line 136 + 0x7 C python24_d.dll!PyGILState_Ensure() Line 430 + 0xc C python24_d.dll!t_bootstrap(void * boot_raw=0x02801d48) Line 431 + 0x5 C python24_d.dll!bootstrap(void * call=0x04f0d264) Line 166 + 0x7 C msvcr71d.dll!_threadstart(void * ptd=0x026a2320) Line 196 + 0xd C I've been seeing this sort of error on-and-off for at least a year with my Python 2.3 install. It's the usual reason my spambayes popproxy dies. I can't recell seeing it before on Windows or while running the test suite. Jeremy

3 3

[OT] stats on type-inferencing atomic types in local variables in the stdlib
by Brett C. 2 অক্টোবর, 2004

2 অক্টোবর, 2004

My thesis (which, for those who don't know, was to come up with a way to do type inferencing in the compiler without requiring any semantic changes; basically type inferencing atomic types assigned to local variables) is now far enough long that I have the algorithm done and I can generate statistics on what opcodes are called with the most common types that I can specifically infer (can also do static type checking on occasion; only triggers were actual unit tests making sure TypeError was raised for certain things like ``~4.2`` and such). Thought some of you might get a kick out of this since the numbers are rather blatent for certain opcodes and methods. To read the stats, the number to the left is the number of times the opcode was compiled (not executed!) with the specific type(s) known for the opcode (if it took two args, then both types are listed; order was considered irrelevant). Now they are listed as integers, so here is the conversion:: Basestring 4 IntegralType 8 FloatType 16 ImagType 32 DictType 64 ListType 128 TupleType 256 For the things named "meth_<something>" that is the method being called immediately on the type. Now realize these numbers are only for opcodes where I could definitely infer the type; ones where it could be more than one type, regardless if those possibilities were very specific, I just ignored it and did not include in the stats. I also tweaked some opcodes knowing how they are more often used. So, for instance, BINARY_MODULO checks specifically for the case of when the left side is a basestring and then just doesn't worry about the other args. Other ones I just didn't bother with all the args since it was not interesting to me in terms of deciding what type-specific opcodes I want to come up with. Anyway, here are the numbers on Lib sans Lib/test (129,814 lines according to SLOCCount) for the ones above 100:: (101, ('BINARY_MULTIPLY', (8, 4))), (106, ('BINARY_SUBSCR', 128)), (118, ('GET_ITER', 128)), (124, ('BINARY_MODULO', None)), (195, ('meth_join', 4)), (204, ('BINARY_ADD', (8, 8))), (331, ('BINARY_ADD', (4, 4))), (513, ('BINARY_LSHIFT', (8, 8))), (840, ('meth_append', 128)), (1270, ('PRINT_ITEM', 4)), (1916, ('BINARY_MODULO', 4)), (12302, ('STORE_SUBSCR', 64))] We sure like our dictionaries (for those that don't know, dictionaries are created by making an empty dict and then basically doing an indivual assignment for each value). We also seem to love to use string interpolation, and printing stuff. Using list.append is also popular. Now the BINARY_LSHIFT is rather interesting, and that ties into the whole issue of how much I can actually infer; since binary work tends to be with all constants I can infer it really easily and so its frequency is rather high. Its actual frequency of use, though, compared to other things probably is not high, though. Plus I doubt Plone, for instance, uses ``<<`` very often so I suspect the opcode will get weeded out when I incorporate stats from the other apps I am taking stats from. As for the stuff I cut out, the surprising thing from those numbers was how few mathematical expressions could be inferred. I checked my numbers with grep and there really is only 3 times where a float constant is divided by a float constant (and they are all in colorsys). I was not expecting that at all. Guess global variables or object attributes tend to have them or I just can't infer the values. Either way I just wasn't expecting that. Anyway, as I said I just thought some people might find this interesting. Don't read into this too much since I am just using these numbers as guidelines for type-specific opcodes to write for use as a quantifiable measurement of the usefulness of type inferencing like this. -Brett P.S.: anyone who is *really* interested I can send you the full stats for the apps I have run my modified version of compile.c against.

2 2

Proposing a sys.special_exceptions tuple
by Nick Coghlan 1 অক্টোবর, 2004

1 অক্টোবর, 2004

I spent some time the other day looking at the use of bare except statements in the standard library. Many of them seemed to fall into the category of 'need to catch anything user code is likely to throw, but shouldn't be masking SystemExit, StopIteration, KeyboardInterrupt, MemoryError, etc'. Changing them to "except Exception:" doesn't help, since all of the above still fit into that category (Tim posted a message recently about rearranging the Exception heirarchy to fix this. Backwards compatibility woes pretty much killed the discussion though). However, another possibility occurred to me: try: # Do stuff except sys.special_exceptions: raise except: # Deal with all the mundane stuff With an appropriately defined tuple, that makes it easy for people to "do the right thing" with regards to critical exceptions. Such a tuple could also be useful for invoking isinstance() and issubclass(). Who knows? If something like this caught on, it might some day be possible to kill a Python script with a single press of Ctrl-C };> Cheers, Nick. -- Nick Coghlan Brisbane, Australia

6 9

Running a module as a script
by Nick Coghlan 1 অক্টোবর, 2004

1 অক্টোবর, 2004

Patch # 1035498 attempts to implement the semantics suggested by Ilya and Anthony and co. "python -m module" Means: - find the source file for the relevant module (using the standard locations for module import) - run the located script as __main__ (note that containing packages are NOT imported first - it's as if the relevant module was executed directly from the command line) - as with '-c' anything before the option is an argument to the interpreter, anything after is an argument to the script The allowed modules are those whose associated source file meet the normal rules for a command line script. I believe that means .py and .pyc files only (e.g. "python -m profile" works, but "python -m hotshot" does not). Special import hooks (such as zipimport) almost certainly won't work (since I don't believe they work with the current command line script mechanism). Cheers, Nick. -- Nick Coghlan Brisbane, Australia

4 7

Another test_compiler mystery
by Tim Peters 1 অক্টোবর, 2004

1 অক্টোবর, 2004

I've noticed several times now, in both debug and release builds, that if I run regrtest.py with -uall, *sometimes* it just stops after running test_compiler: $ python_d regrtest.py -uall test_grammar test_opcodes ... test_compare test_compile test_compiler $ There's no indication of error, it just ends. It's not consistent. Happened once when I was running with -v, and test_compiler's output ended here: ... compiling C:\Code\python\lib\test\test_operator.py compiling C:\Code\python\lib\test\test_optparse.py compiling C:\Code\python\lib\test\test_os.py compiling C:\Code\python\lib\test\test_ossaudiodev.py compiling C:\Code\python\lib\test\test_parser.py In particular, there's no Ran M tests in Ns output, so it doesn't look like unittest (let alone regrtest) ever got control back. Hmm. os.listdir() is in sorted order on NTFS, so test_compiler should be chewing over a lot more files after test_parser.py. *This* I could blame on a blown C stack -- although I'd expect a much nastier symptom then than just premature termination. Anyone else?

23 50

Re: [Python-Dev] PEP 334 - Simple Coroutines via SuspendIteration
by Phillip J. Eby 30 সেপ্টেম্বর, 2004

30 সেপ্টেম্বর, 2004

At 11:36 PM 9/30/04 +0100, Michael Sparks wrote: >On Thu, 30 Sep 2004, Phillip J. Eby wrote: >... > > A mechanism to pass values or exceptions into generators > >[ Possibly somewhat off topic, and apologies if it is, and I'm positive > someone's done something similar before, but I think it's relevant to > the discussion in hand -- largely because the above use case *doesn't* > require changes to python... ] I know it doesn't; peak.events does this now, but in order to have a decent programmer interface, the implementation involves a fair amount of magic. Similarly, PEP 334 doesn't call for anything you can't do with a bit of work and magic. I was suggesting, however, that a true "simple co-routine" (similar to a generator but with bidirectional communication of values and exceptions) would be a valuable addition to the language, in the area of simplifying async programming in e.g. Twisted and peak.events. To put it another way: Slap the current title of PEP 334 onto the body of PEP 288, and change its syntax so you have a way to pass values and exceptions *in* to a suspended "coroutine" (a new and different animal from a generator), and I'm sold.

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