Python-Dev April 2007

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105 participants
129 discussions

test_socketserver flakey?
by Guido van Rossum 03 Apr '07

03 Apr '07

The test_socketserver unittest seems to be failing occasionally for me. (Svn HEAD, Ubuntu dapper.) -- --Guido van Rossum (home page: http://www.python.org/~guido/)

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possible urllib bug on Windows XP
by Shane Geiger 02 Apr '07

02 Apr '07

I have a curious situation which might be a bug in urllib (Python 2.5 installed from a .msi file gotten from python.org) when running on Windows XP. (This is running inside a Parallels virtual machine, but I don't see how that matters, because, as you will see in a second, I'm able to access the Web server both by its IP address and name. Here's a screenshot of a console session: http://www.ncee.net/shane/urllib.png You can see from the screenshot: 1. This machine is able to ping the Web server's IP address. 2. I can even access the Web server via the DNS name assigned (www.nce.net) using wget.exe (from UnxUtils). 3. However, when I try to simulate wget.exe by using urllib, I get an error. Here's the urllib command (which, incidentally works fine from my MacBook Pro): python -c "import urllib ; urllib.urlretrieve(\"http://www.ncee.net/shane/test.py\",\"test.py\")" I tested this on a Windows 2000 Server, and urllib behaved normally. Is this possibly a bug on Windows XP? -- Shane Geiger IT Director National Council on Economic Education sgeiger(a)ncee.net | 402-438-8958 | http://www.ncee.net Leading the Campaign for Economic and Financial Literacy

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proposed which.py replacement
by Shane Geiger 02 Apr '07

02 Apr '07

Trent Mick has a module called which.py that might make a nice platform-independent replacement for python2.5/Tools/scripts/which.py. http://www.trentm.com/projects/which/ Why which.py? |which.py| is a small GNU-which replacement. It has the following features: * it is portable (Windows, Linux, Mac OS X, Un*x); * it understands PATHEXT and "App Paths" registration on Windows (i.e. it will find everything that |start| does from the command shell); * it can print all matches on the PATH; * it can note "near misses" on the PATH (e.g. files that match but may not, say, have execute permissions); and * it can be used as a Python module. I also would be happy to have this be a replacement for the |which.py| in the Python CVS tree at |dist/src/Tools/scripts/which.py| which is Unix-specific and not usable as a module; and perhaps for inclusion in the stdlib. -- Shane Geiger IT Director National Council on Economic Education sgeiger(a)ncee.net | 402-438-8958 | http://www.ncee.net Leading the Campaign for Economic and Financial Literacy

6 10

Python+XUL
by Shane Geiger 01 Apr '07

01 Apr '07

Has anyone heard the Python+XUL community cry "I'm not dead yet!" or are they really dead? I haven't seen mentions of new work in these areas lately. XUL in general seems to have died (so many broken links on XUL pages). Was this just a fad? If not, and if there's some really useful of it (especially if in Python) please point it out. -- Shane Geiger IT Director National Council on Economic Education sgeiger(a)ncee.net | 402-438-8958 | http://www.ncee.net Leading the Campaign for Economic and Financial Literacy

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Python 3000 PEP: Postfix type declarations
by Georg Brandl 01 Apr '07

01 Apr '07

PEP: XXX Title: Postfix type declarations Version: $Revision: $ Last-Modified: $Date: $ Author: Georg Brandl <g.brandl(a)gmx.net> Status: Draft Type: Standards Track Content-Type: text/x-rst Created: 01-Apr-2007 Python-Version: 3.0 Abstract ======== This PEP proposes the addition of a postfix type declaration syntax to Python. It also specifies a new ``typedef`` statement which is used to create new mappings between types and declarators. Its acceptance will greatly enhance the Python user experience as well as eliminate one of the warts that deter users of other programming languages from switching to Python. Rationale ========= Python has long suffered from the lack of explicit type declarations. Being one of the few aspects in which the language deviates from its Zen, this wart has sparked many a discussion between Python heretics and members of the PSU (for a few examples, see [EX1]_, [EX2]_ or [EX3]_), and it also made it a large-scale enterprise success unlikely. However, if one wants to put an end to this misery, a decent Pythonic syntax must be found. In almost all languages that have them, type declarations lack this quality: they are verbose, often needing *multiple words* for a single type, or they are hard to comprehend (e.g., a certain language uses completely unrelated [#]_ adjectives like ``dim`` for type declaration). Therefore, this PEP combines the move to type declarations with another bold move that will once again prove that Python is not only future-proof but future-embracing: the introduction of Unicode characters as an integral constituent of source code. Unicode makes it possible to express much more with much less characters, which is in accordance with the Zen ("Readability counts.") [ZEN]_. Additionally, it eliminates the need for a separate type declaration statement, and last but not least, it makes Python measure up to Perl 6, which already uses Unicode for its operators. [#]_ Specification ============= When the type declaration mode is in operation, the grammar is changed so that each ``NAME`` must consist of two parts: a name and a type declarator, which is exactly one Unicode character. The declarator uniquely specifies the type of the name, and if it occurs on the left hand side of an expression, this type is enforced: an ``InquisitionError`` exception is raised if the returned type doesn't match the declared type. [#]_ Also, function call result types have to be specified. If the result of the call does not have the declared type, an ``InquisitionError`` is raised. Caution: the declarator for the result should not be confused with the declarator for the function object (see the example below). Type declarators after names that are only read, not assigned to, are not strictly necessary but enforced anyway (see the Python Zen: "Explicit is better than implicit."). The mapping between types and declarators is not static. It can be completely customized by the programmer, but for convenience there are some predefined mappings for some built-in types: ========================= =================================================== Type Declarator ========================= =================================================== ``object`` � (REPLACEMENT CHARACTER) ``int`` ℕ (DOUBLE-STRUCK CAPITAL N) ``float`` ℮ (ESTIMATED SYMBOL) ``bool`` ✓ (CHECK MARK) ``complex`` ℂ (DOUBLE-STRUCK CAPITAL C) ``str`` ✎ (LOWER RIGHT PENCIL) ``unicode`` ✒ (BLACK NIB) ``tuple`` ⒯ (PARENTHESIZED LATIN SMALL LETTER T) ``list`` ♨ (HOT SPRINGS) ``dict`` ⧟ (DOUBLE-ENDED MULTIMAP) ``set`` ∅ (EMPTY SET) (*Note:* this is also for full sets) ``frozenset`` ☃ (SNOWMAN) ``datetime`` ⌚ (WATCH) ``function`` ƛ (LATIN SMALL LETTER LAMBDA WITH STROKE) ``generator`` ⚛ (ATOM SYMBOL) ``Exception`` ⌁ (ELECTRIC ARROW) ========================= =================================================== The declarator for the ``None`` type is a zero-width space. These characters should be obvious and easy to remember and type for every programmer. Unicode replacement units ========================= Since even in our modern, globalized world there are still some old-fashioned rebels who can't or don't want to use Unicode in their source code, and since Python is a forgiving language, a fallback is provided for those: Instead of the single Unicode character, they can type ``name${UNICODE NAME OF THE DECLARATOR}$``. For example, these two function definitions are equivalent:: def fooƛ(xℂ): return None and :: def foo${LATIN SMALL LETTER LAMBDA WITH STROKE}$(x${DOUBLE-STRUCK CAPITAL C}$): return None${ZERO WIDTH NO-BREAK SPACE}$ This is still easy to read and makes the full power of type-annotated Python available to ASCII believers. The ``typedef`` statement ========================= The mapping between types and declarators can be extended with this new statement. The syntax is as follows:: typedef_stmt ::= "typedef" expr DECLARATOR where ``expr`` resolves to a type object. For convenience, the ``typedef`` statement can also be mixed with the ``class`` statement for new classes, like so:: typedef class Foo☺(object�): pass Example ======= This is the standard ``os.path.normpath`` function, converted to type declaration syntax:: def normpathƛ(path✎)✎: """Normalize path, eliminating double slashes, etc.""" if path✎ == '': return '.' initial_slashes✓ = path✎.startswithƛ('/')✓ # POSIX allows one or two initial slashes, but treats three or more # as single slash. if (initial_slashes✓ and path✎.startswithƛ('//')✓ and not path✎.startswithƛ('///')✓)✓: initial_slashesℕ = 2 comps♨ = path✎.splitƛ('/')♨ new_comps♨ = []♨ for comp✎ in comps♨: if comp✎ in ('', '.')⒯: continue if (comp✎ != '..' or (not initial_slashesℕ and not new_comps♨)✓ or (new_comps♨ and new_comps♨[-1]✎ == '..')✓)✓: new_comps♨.appendƛ(comp✎) elif new_comps♨: new_comps♨.popƛ()✎ comps♨ = new_comps♨ path✎ = '/'.join(comps♨)✎ if initial_slashesℕ: path✎ = '/'*initial_slashesℕ + path✎ return path✎ or '.' As you can clearly see, the type declarations add expressiveness, while at the same time they make the code look much more professional. Compatibility issues ==================== To enable type declaration mode, one has to write:: from __future__ import type_declarations which enables Unicode parsing of the source [#]_, makes ``typedef`` a keyword and enforces correct types for all assignments and function calls. References ========== .. [EX1] http://mail.python.org/pipermail/python-list/2003-June/210588.html .. [EX2] http://mail.python.org/pipermail/python-list/2000-May/034685.html .. [EX3] http://groups.google.com/group/comp.lang.python/browse_frm/thread/6ae8c6add… .. [#] Though, if you know the language in question, it may not be *that* unrelated. .. [ZEN] http://www.python.org/dev/peps/pep-0020/ .. [#] Well, it would, if there was a Perl 6. .. [#] Since the name ``TypeError`` is already in use, this name has been chosen for obvious reasons. .. [#] The encoding in which the code is written is read from a standard coding cookie. There will also be an autodetection mechanism, invoked by ``from __future__ import encoding_hell``. Acknowledgements ================ Many thanks go to Armin Ronacher, Alexander Schremmer and Marek Kubica who helped find the most suitable and mnemonic declarator for built-in types. Thanks also to the Unicode Consortium for including all those useful characters in the Unicode standard. Copyright ========= This document has been placed in the public domain. .. Local Variables: coding: utf-8 mode: indented-text indent-tabs-mode: nil sentence-end-double-space: t fill-column: 70 End:

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BaseException pickle issue
by Eric Huss 01 Apr '07

01 Apr '07

Some subclasses of Exception are no longer pickleable in Python 2.5. An example: class A(Exception): def __init__(self, foo): self.foo = foo The key problem here is if you do not somehow set self.args to the correct arguments (via Exception.__init__ or setting self.args directly), you will get a TypeError when you try to unpickle it: TypeError: __init__() takes exactly 2 arguments (1 given) I do not think this is unusual. I found a few examples in Python's standard library that have this problem: subprocess.CalledProcessError HTMLParser.HTMLParseError httplib.UnknownProtocol, httplib.IncompleteRead, httplib.BadStatusLine optparse.OptParseError pickle._Stop and on and on... Does anyone have any thoughts about this? Is it a bug? I can imagine one could argue that exceptions should call the base __init__ method to properly set args, but there are so many exceptions out there that do not do this that it would be very difficult to track them all down. I removed the __reduce__ and __setstate__ methods from BaseException and everything seems to just work. Pickling/unpickling works for all protocols whether or not you set self.args. Is this an appropriate solution? I'm not sure what the motivation for having these methods is. -Eric

2 2

Get 2.5 changes in now, branch will be frozen soon
by Neal Norwitz 01 Apr '07

01 Apr '07

This is a reminder that the 2.5 branch will be frozen early next week. If there are changes you want to get into 2.5.1, they should be checked in within a few days. Be conservative! There will be a 2.5.2, it's better to wait than to have to make a new release for one rushed feature. If you don't believe, just wait until Anthony shows up at your doorstep. :-) n

7 8

Python Documentation Problem Example
by xah lee 01 Apr '07

01 Apr '07

Python Doc Problem Example: os.path.split() Xah Lee, 20050918 Quote from: http://www.python.org/doc/2.4.1/lib/module-os.path.html « split(path) Split the pathname path into a pair, (head, tail) where tail is the last pathname component and head is everything leading up to that. The tail part will never contain a slash; if path ends in a slash, tail will be empty. If there is no slash in path, head will be empty. If path is empty, both head and tail are empty. Trailing slashes are stripped from head unless it is the root (one or more slashes only). In nearly all cases, join(head, tail) equals path (the only exception being when there were multiple slashes separating head from tail). » This confusive verbiage is a result of the author's pretention in a austere style and his failure to think clearly before writing. Suggested rewrite: « split(path) returns a pair (dirname,filename), where dirname is the part of path up to the last slash, and filename is the rest of the string after the last slash. Exceptional cases are: • if path is a single slash (or repeated), then path == dirname and filename is empty. • If the last slash is repeated, they are treated as one single slash. » I was working on a program where i needed to split a path into dirname, corename, and suffix. I came to this page and took me a while to understand what split() is about. There are other path related functions splitext(), splitdrive (), basename(), dirname(). User has to scan the whole page and read painfully each one to fully understand how to choose and use them for the task at hand. As i have explained before (see references at bottom), documentation should be organized oriented towards programer's tasks, not alphabetically, compiler view, or computer sciency scheme. On this os.path module, split(), splittext(), dirname(), basename() should all be under one section. This way, their usefulness and each's fitness becomes clearer, and also easier to document as a collective. Other functions that test files or get info about files should be grouped together. Don't be afraid of having functions that won't fit into some grouping scheme. For exapmle, the walk() and supports_unicode_filenames() can be lumped at the bottom as Other. The need to present materials in some aloof, computer sciency, academic, technically precise way is a major usability problem of the Python doc. (the Pythoners's need to present materials in a formal style is a backlash of the happy-go-lucky sloppiness of unix/perl community. However, they being pretty much the same crowd without significant critical thinking and writing skills, cannot do better by hiding in formality.) Also, at the top we see: Warning: On Windows, many of these functions do not properly support UNC pathnames. splitunc() and ismount() do handle them correctly. As indicated before, this is a exhibition of tech geeking and jargonizing. If this warning is necessary, place it at the bottom of the page as a footnote. Also, spell out UNC, and provide a link to its proper spec. Tech geekers are very pretentious and cryptic in their tech docs. They are afraid, as if spelling out UNC would make them unprofessional, that their peers would deem them inferior. There are a myriad of technical standards that any programer could only be familiar with a fraction, confined to his area of expertise. Standards and its acronyms come and go, and each with varying degrees of precision, actual relevance, and they are intermingled with de facto practices in the commercial world that may not even have official names. The tech geekers are clouded by their tech-expertise. The purpose of documentation is not some cold academic presentation. Vast majority who came to use os.path wouldn't know what UNC is nor do they need to know. Spell things out when in doubt. UNC here, isn't really a significant “standard”. This warning should be left out. Suggestions: * Regroup path manipulating functions together, file info functions together, etc. * After regrouping the functions, much of the writing can be simplified since these functions are doing similar tasks. Writing can focus on their differences. Rewrite them with a focus on what users needs to do. Add examples in intricate situations. Avoid the computer science thesis writing style. * Remove the UNC warning at the top. ----- Here are a few other Python doc problems i've written in the past years: Python doc problem example: os.system() http://xahlee.org/perl-python/python_doc_os.html Python Doc Problem Example: os.path.split() http://xahlee.org/perl-python/python_doc_os_path_split.html Python Doc Problem Example: sort() http://xahlee.org/perl-python/python_doc_sort.html Python Doc Problem Example: gzip module http://xahlee.org/perl-python/python_doc_gzip.html Xah xah(a)xahlee.org ∑ http://xahlee.org/ ☄

1 0

Summary of Tracker Issues
by Tracker 31 Mar '07

31 Mar '07

ACTIVITY SUMMARY (03/25/07 - 04/01/07) 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. 1647 open ( +3) / 8584 closed ( +2) / 10231 total ( +5) Average duration of open issues: 751 days. Median duration of open issues: 700 days. Open Issues Breakdown open 1647 ( +3) pending 0 ( +0) Issues Created Or Reopened (5) ______________________________ Buy Tramadol online 03/25/07 CLOSED http://bugs.python.org/issue1023 created conor2k Testing bugs.python.org domain 03/26/07 CLOSED http://bugs.python.org/issue1024 created izak Test issue 03/26/07 http://bugs.python.org/issue1025 created loewis Test issue, to report@ 03/27/07 http://bugs.python.org/issue1026 created forsberg base64.urlsafe_b64encode() shouldn't use the = character 03/28/07 http://bugs.python.org/issue1027 created onlinestocktrading Issues Now Closed (2) _____________________ Buy Tramadol online 3 days http://bugs.python.org/issue1023 amk Testing bugs.python.org domain 0 days http://bugs.python.org/issue1024 izak

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Python-Dev April 2007