Mailman 3 July 2010 - Python-Dev

Re: [Python-Dev] Set the namespace free!
by John Nagle July 22, 2010

July 22, 2010

On 7/22/2010 5:45 AM, python-dev-request(a)python.org wrote: > Message: 10 > Date: Thu, 22 Jul 2010 16:04:00 +0200 > From: Bartosz Tarnowski<bartosz-tarnowski(a)zlotniki.pl> > To:python-dev@python.org > Subject: [Python-Dev] Set the namespace free! > Message-ID:<4C484FD0.2080803(a)zlotniki.pl> > Content-Type: text/plain; charset=UTF-8; format=flowed > > > Hello, guys. > > Python has more and more reserved words over time. It becomes quite annoying, > since you can not use variables and attributes of such names. Suppose I want to > make an XML parser that reads a document and returns an object with attributes > corresponding to XML element attributes: > > > elem = parse_xml("<element param='boo'/>") > > print elem.param > > What should I do then, when the attribute is a reserver word? That's a misuse of attributes. When you need objects with unconstrained fields, inherit them from "dict", and write print(elem['param']) This protects you not only from name clashes, but from difficulties with names that don't fit Python attribute syntax. (BeautifulSoup occasionally crashes due to this problem when parsing malformed HTML). You can still provide a "__getattr__" function, if desired, for convenient access to commonly used attributes. Using "setattr" to set attributes, where the attribute string comes from an external source, can create a security hole. Remember that you can override functions on an object, for that object only, by setting an attribute. This offers the opportunity for an attack similar to SQL injection. Think about what this can do to a parser that has and calls a method "display" for each element: <element display='lambda x : subprocess.Popen("rm -r -f /")'> You are pwned. John Nagle

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Issues #7717 and #7718 ask for Stuart Shelton contributor agreement
by Mark Lawrence July 22, 2010

July 22, 2010

I believe that Pat Campbell is responsible for handling contributor agreements. I'm trying to find out if we have one from Stuart Sheldon. Could someone in the know please forward this to Pat, then we'll be able to move these issues. TIA. Mark Lawrence.

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Timeouts for subprocess module
by Reid Kleckner July 22, 2010

July 22, 2010

Hi python-dev, I've been working through a patch to add timeouts to the subprocess module: http://bugs.python.org/issue5673 It's gotten a fair amount of review, and I'm planning to commit it. Since it's my first contribution, I'm taking Georg's suggestion to send mail to python-dev to see if anyone objects. If not, I'll commit it to the py3k branch tomorrow night. Reid

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Unladen swallow status
by Reid Kleckner July 21, 2010

July 21, 2010

On Wed, Jul 21, 2010 at 8:11 AM, Tim Golden <mail(a)timgolden.me.uk> wrote: > Brett suggested that > the Unladen Swallow merge to trunk was waiting for some work to complete > on the JIT compiler and Georg, as release manager for 3.2, confirmed that > Unladen Swallow would not be merged before 3.3. Yeah, this has slipped. I have patches that need review, and Jeff and Collin have been distracted with other work. Hopefully when one of them gets around to that, I can proceed with the merge without blocking on them. Reid

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Curious datetime method
by Alexander Belopolsky July 21, 2010

July 21, 2010

I always thought that date.today() was a date class method and its availability as a datetime method was an artifact of datetime inheritance from date. I thought datetime.today() would be just the same as date.today(). It turned out I was wrong. Instead, datetime.today() is more like datetime.now(). Almost. >>> datetime.today() datetime.datetime(2010, 7, 16, 20, 5, 10, 710143) The documentation says X.today() is equivalent to X.fromtimestamp(time.time()) and this is literary true: >>> class X(datetime): ... @classmethod ... def fromtimestamp(cls, t): ... return "whatever" ... >>> X.today() 'whatever' Unlike datetime.now() which gets time directly from OS, datetime.today() calls time.time(), gets timestamp as float and breaks it into integer datetime components in fromtimestamp(). This method is slow, relies on various poorly defined float to integer conversions and cannot produce anything other than local time as a naive datetime object. I wonder why would anyone want to use datetime.today() instead of datetime.now()?

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MSDN subscription extensions?
by David Bolen July 20, 2010

July 20, 2010

As one of the beneficiaries of the efforts (much appreciated) last year to obtain Microsoft MSDN subscriptions for developers/testers (in my case, primarily buildbot operation), I was wondering if anyone might know if those subscriptions will be able to be renewed this year? -- David

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Markup of command-line options in Python's .rst documentation
by Eli Bendersky July 20, 2010

July 20, 2010

Hello, I'm currently working, together with Terry Reedy, on improving the documentation of the trace module, and I ran into a peculiar convention of marking command-line options which seems to be widespread. Consider the documentation of timeit, for instance: http://docs.python.org/dev/py3k/library/timeit.html The "--help" option appears as a hyperlink leading to http://docs.python.org/dev/py3k/using/cmdline.html#cmdoption--help, which is hardly relevant or useful. The same applies for several command-line options documented for the trace module (for example -m and -s). This is a result of the following markup (again, taking the timeit module as an example) in the relevant .rst file (Doc/library/timeit.rst): -h/:option:`--help` print a short usage message and exit The :option: markup seems to be translated by Sphinx into a link to the Python executable's own command line arguments. This creates the aforementioned problem in other modules as well, for example unittest. Is there really any merit in marking command-line options for modules with :option:, if it's only useful for Python's own options? Eli

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Use of coding cookie in 3.x stdlib
by Alexander Belopolsky July 19, 2010

July 19, 2010

I was looking at the inspect module and noticed that it's source starts with "# -*- coding: iso-8859-1 -*-". I have checked and there are no non-ascii characters in the file. There are several other modules that still use the cookie: Lib/ast.py:# -*- coding: utf-8 -*- Lib/getopt.py:# -*- coding: utf-8 -*- Lib/inspect.py:# -*- coding: iso-8859-1 -*- Lib/pydoc.py:# -*- coding: latin-1 -*- Lib/shlex.py:# -*- coding: iso-8859-1 -*- Lib/encodings/punycode.py:# -*- coding: utf-8 -*- Lib/msilib/__init__.py:# -*- coding: utf-8 -*- Lib/sqlite3/__init__.py:#-*- coding: ISO-8859-1 -*- Lib/sqlite3/dbapi2.py:#-*- coding: ISO-8859-1 -*- Lib/test/bad_coding.py:# -*- coding: uft-8 -*- Lib/test/badsyntax_3131.py:# -*- coding: utf-8 -*- I understand that coding: utf-8 is strictly redundant in 3.x. There are cases such as Lib/shlex.py where using encoding other than utf-8 is justified. (See http://svn.python.org/view?view=rev&revision=82560). What are the guidelines for other cases? Should redundant cookies be removed? Since not all editors respect the -*- cookie, I think the answer should be "yes" particularly when the cookie is setting encoding other than utf-8.

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Function Operators
by Christopher Olah July 18, 2010

July 18, 2010

Dear python-dev, In mathematical notation, f*g = z->f(g(z)) and f^n = f*f*f... (n times). I often run into situations in python where such operators could result in cleaner code. Eventually, I decided to implement it myself and see how it worked in practice. However, my intuitive implementation [1] doesn't seem to work. In particular, despite what it says in function's documentation, function does not seem to be in __builtin__. Furthermore, when I try to implement this through type(f) (where f is a function) I get invalid syntax errors. I hope I haven't made some trivial error; I'm rather inexperienced as a pythonist. Christopher Olah [1] Sketch: def __builtin__.function.__mul__(self, f): return lambda x: self(f(x)) def __builtin__.function.__pow__(self, n): return lambda x: reduce(lambda a,b: [f for i in range(n)]+[x])

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Windows process creation flags
by ipatrol6010＠yahoo.com July 18, 2010

July 18, 2010

I was reading http://msdn.microsoft.com/en-us/library/ms684863%28v=VS.85%29.aspx and http://stackoverflow.com/questions/89228/how-to-call-external-command-in-py… when I realized that the process creation flags for subprocess.Popen on Windows are not specified anywhere in the standard library. I was thinking of putting them in os or subprocess by prepending a P_ to their MSVC++ names as listed above. It seems like a fairly minor, uncontroversial idea. Can we patch it in? Please CC all replies to this message back to ipatrol6010(a)yahoo.com

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