[RELEASED] Python 3.2 beta 2
-BEGIN PGP SIGNED MESSAGE- Hash: SHA1 On behalf of the Python development team, I'm happy to announce the second beta preview release of Python 3.2. Python 3.2 is a continuation of the efforts to improve and stabilize the Python 3.x line. Since the final release of Python 2.7, the 2.x line will only receive bugfixes, and new features are developed for 3.x only. Since PEP 3003, the Moratorium on Language Changes, is in effect, there are no changes in Python's syntax and built-in types in Python 3.2. Development efforts concentrated on the standard library and support for porting code to Python 3. Highlights are: * numerous improvements to the unittest module * PEP 3147, support for .pyc repository directories * PEP 3149, support for version tagged dynamic libraries * PEP 3148, a new futures library for concurrent programming * PEP 384, a stable ABI for extension modules * PEP 391, dictionary-based logging configuration * an overhauled GIL implementation that reduces contention * an extended email package that handles bytes messages * countless fixes regarding bytes/string issues; among them full support for a bytes environment (filenames, environment variables) * many consistency and behavior fixes for numeric operations * a sysconfig module to access configuration information * a pure-Python implementation of the datetime module * additions to the shutil module, among them archive file support * improvements to pdb, the Python debugger For a more extensive list of changes in 3.2, see http://docs.python.org/3.2/whatsnew/3.2.html To download Python 3.2 visit: http://www.python.org/download/releases/3.2/ Please consider trying Python 3.2 with your code and reporting any bugs you may notice to: http://bugs.python.org/ Enjoy! - -- Georg Brandl, Release Manager georg at python.org (on behalf of the entire python-dev team and 3.2's contributors) -BEGIN PGP SIGNATURE- Version: GnuPG v1.4.11 (GNU/Linux) iEYEARECAAYFAk0Q/aAACgkQN9GcIYhpnLDf8gCgkLGAsE+T3R505jZc1RxXDYsa NSsAnRGaFjeTm9o2Z5O8FuIzTUG8t1PT =hHzz -END PGP SIGNATURE- -- http://mail.python.org/mailman/listinfo/python-announce-list Support the Python Software Foundation: http://www.python.org/psf/donations/
compiling Python 2.7.1 with readline module fails on Debian (Virtualbox)
Hi, i'm trying to compile Python 2.7.1 on Debian (Virtual Box). Compiling end successfully but readline and curses fail to build. I'm working with virtualenv and I install all my packages in $HOME/local. I've downloaded readline, compiled and installed it in $HOME/local, same with ncurses. Both were the latest releases. But somehow, Python isn't able to build them. I get this message: Failed to build these modules: _curses_curses_panelreadline So it does seems to find the modules. I'm not used to dealing with configure, and make so i can't debug much. I first tried this configure line: ./configure --enable-shared --prefix=$HOME/local Next i tried this one: env CPPFLAGS=-I$HOME/local/include LDFLAGS=-L$HOME/local/lib ./configure --enable-shared --prefix=$HOME/local But make yields the same error. Any clues on what I do wrong? The source of ncurses and readline are placed in $HOME/src. Both packages are installed in $HOME/local Thanks for any advice, Regards, Benedict -- http://mail.python.org/mailman/listinfo/python-list
Question regarding Higher-Order-Programming in Python
I am about to learn Higher-Order-Programming with Lisp, Haskell, and
Python. Some people who have gone completely out of their mind call
this FP.
In Haskell I learned that when I use map on a list it starts nesting
as soon as I start adding elements. If I do not like the nesting I use
ConcatMap.
In Python I have a similar scenario. I have a generator which creates
some combinatorics of a input dictionary. The list starts nesting. Now
I could use reduce(concat, ...) which would be the correct thing from
a functional perspective. But from a resource utilization perspective
it is not a good idea since the reduce is executing the generator.
I tried to illustrate this using a small example (the often in
combinatorics the real thing would be much bigger that is why I need
to use a generator):
from operator import itemgetter, concat
import itertools as it
from functools import partial
dims = {'number': [1,2,3], 'letter': ['a', 'b'], 'special': ['+', '-']}
dims
{'special': ['+', '-'], 'number': [1, 2, 3], 'letter': ['a', 'b']}
def get_products(keys):
... # helper to get products from keys in the following form:
... # [('bold', True), ('color', 'black')]
... values = itemgetter(*keys)(dims)
... product = it.product(*values)
... return map(partial(zip, keys), product)
...
comb = it.combinations(dims, 2)
comb_l = list(comb)
comb_l
[('special', 'number'), ('special', 'letter'), ('number', 'letter')]
res = map(get_products, comb_l)
res
[[[('special', '+'), ('number', 1)], [('special', '+'), ('number',
2)], [('special', '+'), ('number', 3)], [('special', '-'), ('number',
1)], [('special', '-'), ('number', 2)], [('special', '-'), ('number',
3)]], [[('special', '+'), ('letter', 'a')], [('special', '+'),
('letter', 'b')], [('special', '-'), ('letter', 'a')], [('special',
'-'), ('letter', 'b')]], [[('number', 1), ('letter', 'a')],
[('number', 1), ('letter', 'b')], [('number', 2), ('letter', 'a')],
[('number', 2), ('letter', 'b')], [('number', 3), ('letter', 'a')],
[('number', 3), ('letter', 'b')]]] # the resulting list is nested one
level to deep caused by the map(get_products, ..
My problem is that I want to get single elements from the generator
like [('special', '+'), ('number', 1)]. But this does not work because
the list is now nested to deep.
That is what I expect: (I could get something like that with the
following res = reduce(concat, res)
[[('special', '+'), ('number', 1)], [('special', '+'), ('number', 2)],
[('special', '+'), ('number', 3)], [('special', '-'), ('number', 1)],
[('special', '-'), ('number', 2)], [('special', '-'), ('number', 3)],
[('special', '+'), ('letter', 'a')], [('special', '+'), ('letter',
'b')], [('special', '-'), ('letter', 'a')], [('special', '-'),
('letter', 'b')], [('number', 1), ('letter', 'a')], [('number', 1),
('letter', 'b')], [('number', 2), ('letter', 'a')], [('number', 2),
('letter', 'b')], [('number', 3), ('letter', 'a')], [('number', 3),
('letter', 'b')]]
I have seen the problem many times but so far I could not google a
solution on the web.
By the way do you know any substantial example using FP in Python
(generators, imap, ifilter, ...)?
--
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Mo Better Lisp Jobs
Check it out: http://lispjobs.wordpress.com/2010/12/22/lisp-developer-mcna-fort-laurderdale-florida/ We already have six splendid folks but business is booming and at least one contract bid has to happen faster than we thought (potential client moved it up) so we are looking to take on a couple more. Lisp wannabe Rails gurus lurking here, plz note the opportunity described in the listing. The rest of the cross-posting is to find great coders with light Lisp. We can talk. HK -- http://mail.python.org/mailman/listinfo/python-list
Re: Question regarding Higher-Order-Programming in Python
Mark Fink wrote:
I am about to learn Higher-Order-Programming with Lisp, Haskell, and
Python. Some people who have gone completely out of their mind call
this FP.
In Haskell I learned that when I use map on a list it starts nesting
as soon as I start adding elements. If I do not like the nesting I use
ConcatMap.
In Python I have a similar scenario. I have a generator which creates
some combinatorics of a input dictionary. The list starts nesting. Now
I could use reduce(concat, ...) which would be the correct thing from
a functional perspective. But from a resource utilization perspective
it is not a good idea since the reduce is executing the generator.
I tried to illustrate this using a small example (the often in
combinatorics the real thing would be much bigger that is why I need
to use a generator):
from operator import itemgetter, concat
import itertools as it
from functools import partial
dims = {'number': [1,2,3], 'letter': ['a', 'b'], 'special': ['+', '-']}
dims
{'special': ['+', '-'], 'number': [1, 2, 3], 'letter': ['a', 'b']}
def get_products(keys):
... # helper to get products from keys in the following form:
... # [('bold', True), ('color', 'black')]
... values = itemgetter(*keys)(dims)
... product = it.product(*values)
... return map(partial(zip, keys), product)
...
comb = it.combinations(dims, 2)
comb_l = list(comb)
comb_l
[('special', 'number'), ('special', 'letter'), ('number', 'letter')]
res = map(get_products, comb_l)
res
[[[('special', '+'), ('number', 1)], [('special', '+'), ('number',
2)], [('special', '+'), ('number', 3)], [('special', '-'), ('number',
1)], [('special', '-'), ('number', 2)], [('special', '-'), ('number',
3)]], [[('special', '+'), ('letter', 'a')], [('special', '+'),
('letter', 'b')], [('special', '-'), ('letter', 'a')], [('special',
'-'), ('letter', 'b')]], [[('number', 1), ('letter', 'a')],
[('number', 1), ('letter', 'b')], [('number', 2), ('letter', 'a')],
[('number', 2), ('letter', 'b')], [('number', 3), ('letter', 'a')],
[('number', 3), ('letter', 'b')]]] # the resulting list is nested one
level to deep caused by the map(get_products, ..
My problem is that I want to get single elements from the generator
like [('special', '+'), ('number', 1)]. But this does not work because
the list is now nested to deep.
Like this?
[(k, v) for k, vv in dims.iteritems() for v in vv]
[('special', '+'), ('special', '-'), ('number', 1), ('number', 2),
('number', 3), ('letter', 'a'), ('letter', 'b')]
But these are just glorified for-loops, so:
list(chain.from_iterable(starmap(product, izip(izip(dims.iterkeys()),
dims.itervalues()
[('special', '+'), ('special', '-'), ('number', 1), ('number', 2),
('number', 3), ('letter', 'a'), ('letter', 'b')]
Peter
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issubclass(dict, Mapping)
In a message (4cf97c94$0$30003$c3e8da3$54964...@news.astraweb.com) on a different thread, Steven D'Aprano tells me: I suspect you're trying to make this more complicated than it actually is. You keep finding little corner cases that expose implementation details (such as the heap-types issue above) and leaping to the erroneous conclusion that because you didn't understand this tiny little corner of Python's class model, you didn't understand any of it. Python's object model is relatively simple, but it does occasionally expose a few messy corners. I disagree with your assessment. What you call little corner cases I call fundamental, as in you can't really call yourself competent with Python if you're ignorant about them. To use a term I first saw in an article by Joel Spolsky (http://is.gd/je42O), Python's object model is a rather leaky abstraction. This refers to the situation in which a user is not shielded from the implementation details. When an abstraction leaks, implementation details are no longer negligible, they cease to be little corner cases. Here's another example, fresh from today's crop of wonders: (v. 2.7.0) from collections import Mapping issubclass(dict, Mapping) True dict.__bases__ (type 'object',) [issubclass(b, Mapping) for b in dict.__bases__] [False] So dict is a subclass of Mapping, even though none of the bases of dict is either Mapping or a subclass of Mapping. Great. I suspect this is another abstraction leak (dict is *supposed* to be a Python class like all others, but in fact it's not *really*. You see, once upon a time...). I conclude that, for me to understand Python's (rather leaky) object model abstraction, I have to understand its underlying implementation. Unfortunately, as far as I know, there's no other choice but to study the source code, since there's no other more readable description of this implementation. Maybe there are fewer abstraction leaks in 3.0... ~kj -- http://mail.python.org/mailman/listinfo/python-list
Re: issubclass(dict, Mapping)
On Wed, 2010-12-22 at 14:20 +, kj wrote: In a message (4cf97c94$0$30003$c3e8da3$54964...@news.astraweb.com) on a different thread, Steven D'Aprano tells me: I suspect you're trying to make this more complicated than it actually is. You keep finding little corner cases that expose implementation details (such as the heap-types issue above) and leaping to the erroneous conclusion that because you didn't understand this tiny little corner of Python's class model, you didn't understand any of it. Python's object model is relatively simple, but it does occasionally expose a few messy corners. I disagree with your assessment. What you call little corner cases I call fundamental, as in you can't really call yourself competent with Python if you're ignorant about them. To use a term I first saw in an article by Joel Spolsky (http://is.gd/je42O), Python's object model is a rather leaky abstraction. This refers to the situation in which a user is not shielded from the implementation details. When an abstraction leaks, implementation details are no longer negligible, they cease to be little corner cases. Here's another example, fresh from today's crop of wonders: (v. 2.7.0) from collections import Mapping issubclass(dict, Mapping) True dict.__bases__ (type 'object',) [issubclass(b, Mapping) for b in dict.__bases__] [False] So dict is a subclass of Mapping, even though none of the bases of dict is either Mapping or a subclass of Mapping. Great. I suspect this is another abstraction leak (dict is *supposed* to be a Python class like all others, but in fact it's not *really*. You see, once upon a time...). I conclude that, for me to understand Python's (rather leaky) object model abstraction, I have to understand its underlying implementation. Unfortunately, as far as I know, there's no other choice but to study the source code, since there's no other more readable description of this implementation. Maybe there are fewer abstraction leaks in 3.0... Boy howdy are you going to incite the ire of the Pythonistas! IMO, the object model isn't leaky, it is simply adhoc and not really a model at all [write as many 800 page books as you want: if it walks like a zombie duck, smells like a zombie duck - it is still a zombie duck]. Performing introspection in Python is awful and a veritable land-mine of implementation details. The short and honest answer is: avoid doing it whenever possible, try to figure out how to accomplish the task some other way. -- http://mail.python.org/mailman/listinfo/python-list
Re: Question regarding Higher-Order-Programming in Python
list(chain.from_iterable(starmap(product, izip(izip(dims.iterkeys()),
dims.itervalues()
[('special', '+'), ('special', '-'), ('number', 1), ('number', 2),
('number', 3), ('letter', 'a'), ('letter', 'b')]
Peter
so far I have never noticed chain.from_iterable, but many thanks to
you Peter, I have now a beautiful solution to this problem.
from itertools import chain
comb = it.combinations(dims, 2)
l = chain.from_iterable(it.imap(get_products, comb))
l.next()
[('special', '+'), ('number', 1)]
l.next()
[('special', '+'), ('number', 2)]
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Re: issubclass(dict, Mapping)
On Wed, 22 Dec 2010 14:20:51 + (UTC) kj no.em...@please.post wrote: So dict is a subclass of Mapping, even though none of the bases of dict is either Mapping or a subclass of Mapping. Great. I suspect this is another abstraction leak (dict is *supposed* to be a Python class like all others, but in fact it's not *really*. It is. You just haven't read about Python's ABCs (abstract base classes): http://docs.python.org/library/abc.html#abc.ABCMeta « You can also register unrelated concrete classes (even built-in classes) and unrelated ABCs as “virtual subclasses” – these and their descendants will be considered subclasses of the registering ABC by the built-in issubclass() function, but the registering ABC won’t show up in their MRO (Method Resolution Order) nor will method implementations defined by the registering ABC be callable (not even via super()). » With a very simple example in the register() doc: http://docs.python.org/library/abc.html#abc.ABCMeta.register Regards Antoine. -- http://mail.python.org/mailman/listinfo/python-list
Re: Google AI challenge: planet war. Lisp won.
On Dec 20, 10:06 pm, Jon Harrop use...@ffconsultancy.com wrote: Wasn't that the challenge where they wouldn't even accept solutions written in many other languages (including both OCaml and F#)? Ocaml is one of the supported lang. See: http://ai-contest.com/starter_packages.php there are 12 teams using OCaml. See: http://ai-contest.com/rankings.php (click on the lang to see all teams using that lang) Xah -- http://mail.python.org/mailman/listinfo/python-list
Re: issubclass(dict, Mapping)
On Wed, 22 Dec 2010 09:35:48 -0500 Adam Tauno Williams awill...@whitemice.org wrote: IMO, the object model isn't leaky, it is simply adhoc and not really a model at all [write as many 800 page books as you want: if it walks like a zombie duck, smells like a zombie duck - it is still a zombie duck]. Performing introspection in Python is awful and a veritable land-mine of implementation details. Introspection is fine as long as you stick to officially promoted tools such as isinstance(), issubclass(), dir() or the inspect module. If you start looking inside the pants of the object model, you can have surprises :) Regards Antoine. -- http://mail.python.org/mailman/listinfo/python-list
Re: issubclass(dict, Mapping)
On 12/22/2010 9:20 AM, kj wrote: [...] I suspect this is another abstraction leak (dict is *supposed* to be a Python class like all others, but in fact it's not *really*. You see, once upon a time...). So your suspicions are to be placed above the knowledge of those who really do understand Python's object model? That seems like a recipe for cargo cult programming ... I conclude that, for me to understand Python's (rather leaky) object model abstraction, I have to understand its underlying implementation. Unfortunately, as far as I know, there's no other choice but to study the source code, since there's no other more readable description of this implementation. You don't have to understand the implementation (there are at least five different implementations, which one will you choose as your standard?) Maybe there are fewer abstraction leaks in 3.0... Python deliberately exposes introspection interfaces, which you may use if you wish. As with all introspectable languages (including Java) if you push the envelope you are likely to hit corner cases. As Steven d'Aprano has already said, these *are* corner cases and not the whole of the language. Don't worry about having a complete knowledge of the language before you start to use it. That can induce paralysis ... regards Steve -- Steve Holden +1 571 484 6266 +1 800 494 3119 PyCon 2011 Atlanta March 9-17 http://us.pycon.org/ See Python Video! http://python.mirocommunity.org/ Holden Web LLC http://www.holdenweb.com/ -- http://mail.python.org/mailman/listinfo/python-list
Re: [python-committers] [RELEASED] Python 3.2 beta 2
On 12/22/2010 8:46 AM, Georg Brandl wrote: Am 22.12.2010 02:15, schrieb Nick Coghlan: On Wed, Dec 22, 2010 at 6:18 AM, Georg Brandlge...@python.org wrote: Since PEP 3003, the Moratorium on Language Changes, is in effect, there are no changes in Python's syntax and built-in types in Python 3.2. Minor nit - we actually did tweak a few of the builtin types a bit (mostly the stuff to improve Sequence ABC conformance and to make range objects more list-like) Indeed, I'll fix this wording for the next announcement. (And I will mention SSL, sorry Antoine). If you're only going to mention some vague some builtins had minor changes, then I'm fine with that. If you're going to enumerate all such changes, that will be a bigger job. There were 2 such changes I'm aware of: str.format_map (#6081) and the addition of alternate (#) formatting to float, complex and decimal (#7094) __format__ methods. For this announcement I don't think it's necessary to list them all. -- http://mail.python.org/mailman/listinfo/python-list
Re: compiling Python 2.7.1 with readline module fails on Debian (Virtualbox)
On 22/12/2010 9:33, Benedict Verheyen wrote: Hi, i'm trying to compile Python 2.7.1 on Debian (Virtual Box). Compiling end successfully but readline and curses fail to build. I'm working with virtualenv and I install all my packages in $HOME/local. I've downloaded readline, compiled and installed it in $HOME/local, same with ncurses. Both were the latest releases. But somehow, Python isn't able to build them. I get this message: Failed to build these modules: _curses_curses_panelreadline So it does seems to find the modules. I'm not used to dealing with configure, and make so i can't debug much. I first tried this configure line: ./configure --enable-shared --prefix=$HOME/local Next i tried this one: env CPPFLAGS=-I$HOME/local/include LDFLAGS=-L$HOME/local/lib ./configure --enable-shared --prefix=$HOME/local But make yields the same error. Any clues on what I do wrong? The source of ncurses and readline are placed in $HOME/src. Both packages are installed in $HOME/local Thanks for any advice, Regards, Benedict I found some additional info here: http://www.velocityreviews.com/forums/t733455-problem-building-python-2-7-with-enable-shared.html The error -collect2: ld returned 1 exit status is the same error as I'm getting. So what happens is that linking to python2.7 during make, doesn't link to the freshly build library, but to the existing in the system. Is there any solution for this? Or an option i can add to make/config? Cheers, Benedict -- http://mail.python.org/mailman/listinfo/python-list
Regular expression for key = value pairs
Hi all,
suppose I have:
s='a=b, c=d'
and I want to extract sub-strings a,b,c and d from s (and in general
from any longer list of such comma separated pairs).
Some failed attempts:
In [12]: re.findall(r'(.+)=(.+)', s)
Out[12]: [('a=b, c', 'd')]
In [13]: re.findall(r'(.+?)=(.+)', s)
Out[13]: [('a', 'b, c=d')]
In [14]: re.findall(r'(.+)=(.+)*', s)
Out[14]: [('a=b, c', 'd')]
In [15]: re.findall(r'(.+)=(.+),', s)
Out[15]: [('a', 'b')]
In [16]: re.findall(r'(.+)=(.+),?', s)
Out[16]: [('a=b, c', 'd')]
Thanks for your help,
francesco.
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Re: help with link parsing?
On 21-Dec-10 12:22 PM, Jon Clements wrote:
import lxml
from urlparse import urlsplit
doc = lxml.html.parse('http://www.google.com')
print map(urlsplit, doc.xpath('//a/@href'))
[SplitResult(scheme='http', netloc='www.google.co.uk', path='/imghp',
query='hl=entab=wi', fragment=''), SplitResult(scheme='http',
netloc='video.google.co.uk', path='/', query='hl=entab=wv',
fragment=''), SplitResult(scheme='http', netloc='maps.google.co.uk',
path='/maps', query='hl=entab=wl', fragment=''),
SplitResult(scheme='http', netloc='news.google.co.uk', path='/nwshp',
query='hl=entab=wn', fragment=''), ...]
Jon,
What version of Python was used to run this?
Colin W.
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Re: Regular expression for key = value pairs
On Wednesday, December 22, 2010 12:22:22 PM UTC-4, Francesco Napolitano wrote:
Hi all,
suppose I have:
s='a=b, c=d'
and I want to extract sub-strings a,b,c and d from s (and in general
from any longer list of such comma separated pairs).
Some failed attempts:
In [12]: re.findall(r'(.+)=(.+)', s)
Out[12]: [('a=b, c', 'd')]
In [13]: re.findall(r'(.+?)=(.+)', s)
Out[13]: [('a', 'b, c=d')]
In [14]: re.findall(r'(.+)=(.+)*', s)
Out[14]: [('a=b, c', 'd')]
In [15]: re.findall(r'(.+)=(.+),', s)
Out[15]: [('a', 'b')]
In [16]: re.findall(r'(.+)=(.+),?', s)
Out[16]: [('a=b, c', 'd')]
How about the following:
s = 'a=b,c=d'
t = []
for u in s.split(','):
... t.extend(u.split('='))
...
t
['a', 'b', 'c', 'd']
HTH,
André
Thanks for your help,
francesco.
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Re: Regular expression for key = value pairs
2010/12/22 Ciccio franap...@gmail.com:
Hi all,
suppose I have:
s='a=b, c=d'
and I want to extract sub-strings a,b,c and d from s (and in general from
any longer list of such comma separated pairs).
Some failed attempts:
In [12]: re.findall(r'(.+)=(.+)', s)
Out[12]: [('a=b, c', 'd')]
[...]
Thanks for your help,
francesco.
--
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Hi,
I am not sure, the regular expressions are best suited for this task,
but if you have a predictable simple parameter list (with ho
recursion, escaping commas or equal signs etc.), it might be viable;
how about e.g. this pattern?
re.findall(r'([^=\s,]+)=([^=\s,]+)', s)
[('a', 'b'), ('c', 'd')]
vbr
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simple games w/o pygame
I am teaching an 11 year old who wants to learn programming. I chose Python, and it is working well. I seem to remember lots of simple script games, like quizzes, number games etc. that would be good for his tutorial. However, now all I can find is more complex games using Pygame. Can anyone help me out here? -- http://mail.python.org/mailman/listinfo/python-list
Re: How to pop the interpreter's stack?
In mailman.65.1292517591.6505.python-l...@python.org Robert Kern
robert.k...@gmail.com writes:
Obfuscating the location that an exception gets raised prevents a lot of
debugging...
The Python interpreter does a lot of that obfuscation already, and I
find the resulting tracebacks more useful for it.
An error message is only useful to a given audience if that audience
can use the information in the message to modify what they are
doing to avoid the error. It is of no use (certainly no *immediate*
use) to this audience to see tracebacks that go deep into code that
they don't know anything about and cannot change.
For example, consider this:
#-
def foo(x, **k): pass
def bar(*a, **k):
if len(a) 1: raise TypeError('too many args')
def baz(*a, **k): _pre_baz(*a, **k)
def _pre_baz(*a, **k):
if len(a) 1: raise TypeError('too many args')
if __name__ == '__main__':
from traceback import print_exc
try: foo(1, 2)
except: print_exc()
try: bar(1, 2)
except: print_exc()
try: baz(1, 2)
except: print_exc()
#-
(The code in the if __name__ == '__main__' section is meant to
simulate the general case in which the functions defined in this file
are called by third-party code.) When you run this code the output is
this (a few blank lines added for clarity):
Traceback (most recent call last):
File /tmp/ex2.py, line 5, in module
try: foo(1, 2)
TypeError: foo() takes exactly 1 argument (2 given)
Traceback (most recent call last):
File /tmp/ex2.py, line 7, in module
try: bar(1, 2)
File /tmp/example.py, line 4, in bar
if len(a) 1: raise TypeError('too many args')
TypeError: too many args
Traceback (most recent call last):
File /tmp/ex2.py, line 9, in module
try: baz(1, 2)
File /tmp/example.py, line 6, in baz
def baz(*a, **k): _pre_baz(*a, **k)
File /tmp/example.py, line 9, in _pre_baz
if len(a) 1: raise TypeError('too many args')
TypeError: too many args
In all cases, the *programming* errors are identical: functions called
with the wrong arguments. The traceback from foo(1, 2) tells me this
very clearly, and I'm glad that Python is not also giving me the
traceback down to where the underlying C code throws the exception: I
don't need to see all this machinery.
In contrast, the tracebacks from bar(1, 2) and baz(1, 2) obscure the
fundamental problem with useless detail. From the point of view of
the programmer that is using these functions, it is of no use to know
that the error resulted from some raise TypeError statement
somewhere, let alone that this happened in some obscure, private
function _pre_baz.
Perhaps I should have made it clearer in my original post that the
tracebacks I want to clean up are those from exceptions *explicitly*
raised by my argument-validating helper function, analogous to
_pre_baz above. I.e. I want that when my spam function is called
(by code written by someone else) with the wrong arguments, the
traceback looks more like this
Traceback (most recent call last):
File /some/python/code.py, line 123, in module
spam(some, bad, args)
TypeError: the second argument is bad
than like this:
Traceback (most recent call last):
File /some/python/code.py, line 123, in module
spam(some, bad, args)
File /my/niftymodule.py, line 456, in niftymodule
_pre_spam(*a, **k)
File /my/niftymodule.py, line 789, in __pre_spam
raise TypeError('second argument to spam is bad')
TypeError: the second argument is bad
In my opinion, the idea that more is always better in a traceback
is flat out wrong. As the example above illustrates, the most
useful traceback is the one that stops at the deepest point where
the *intended audience* for the traceback can take action, and goes
no further. The intended audience for the errors generated by my
argument-checking functions should see no further than the point
where they called a function incorrectly.
~kj
--
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Re: help with link parsing?
On Dec 22, 4:24 pm, Colin J. Williams cjwilliam...@gmail.com
wrote:
On 21-Dec-10 12:22 PM, Jon Clements wrote:
import lxml
from urlparse import urlsplit
doc = lxml.html.parse('http://www.google.com')
print map(urlsplit, doc.xpath('//a/@href'))
[SplitResult(scheme='http', netloc='www.google.co.uk', path='/imghp',
query='hl=entab=wi', fragment=''), SplitResult(scheme='http',
netloc='video.google.co.uk', path='/', query='hl=entab=wv',
fragment=''), SplitResult(scheme='http', netloc='maps.google.co.uk',
path='/maps', query='hl=entab=wl', fragment=''),
SplitResult(scheme='http', netloc='news.google.co.uk', path='/nwshp',
query='hl=entab=wn', fragment=''), ...]
Jon,
What version of Python was used to run this?
Colin W.
2.6.5 - the lxml library is not a standard module though and needs to
be installed.
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Re: Regular expression for key = value pairs
Ciccio franap...@gmail.com writes:
suppose I have:
s='a=b, c=d'
and I want to extract sub-strings a,b,c and d from s (and in general
from any longer list of such comma separated pairs).
[...]
In [12]: re.findall(r'(.+)=(.+)', s)
Out[12]: [('a=b, c', 'd')]
I think there are two logically separate jobs here: firstly, extracting
the comma-separated pairs, and secondly parsing the individual pairs.
If you want the extra problem of dealing with regular expressions, this
seems to be the way to do it.
R_PAIR = re.compile(r'''
^\s*
([^=\s]|[^=\s][^=]*[^=\s])
\s*=\s*
(\S|\S.*\S)
\s*$
''', re.X)
def parse_pair(pair):
m = R_PAIR.match(pair)
if not m:
raise ValueError, 'not a `KEY = VALUE\' pair'
return m.groups([1, 2])
The former is even easier.
R_COMMA = re.compile(r'\s*,\s*')
kvs = [parse_pair(p) for p in R_COMMA.split(string)]
Apply gold-plating to taste.
But actually, it's much easier to avoid messing with regular expressions
at all.
def parse_pair(pair):
eq = pair.index('=')
return pair[:eq].strip(), pair[eq + 1:].strip()
kvs = [parse_pair(p) for p in string.split(',')]
-- [mdw]
--
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Re: Regular expression for key = value pairs
André andre.robe...@gmail.com writes:
How about the following:
s = 'a=b,c=d'
t = []
for u in s.split(','):
... t.extend(u.split('='))
s = 'a = b = c, d = e'
= ['a ', ' b ', ' c', ' d ', ' e']
Ugh.
-- [mdw]
--
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Re: issubclass(dict, Mapping)
kj wrote: In a message (4cf97c94$0$30003$c3e8da3$54964...@news.astraweb.com) on a different thread, Steven D'Aprano tells me: I suspect you're trying to make this more complicated than it actually is. You keep finding little corner cases that expose implementation details (such as the heap-types issue above) and leaping to the erroneous conclusion that because you didn't understand this tiny little corner of Python's class model, you didn't understand any of it. Python's object model is relatively simple, but it does occasionally expose a few messy corners. I disagree with your assessment. What you call little corner cases I call fundamental, as in you can't really call yourself competent with Python if you're ignorant about them. So where on the sliding scale do you place 'competent'? It sounds to me like you are looking at 'master'. Here's another example, fresh from today's crop of wonders: (v. 2.7.0) from collections import Mapping issubclass(dict, Mapping) True dict.__bases__ (type 'object',) [issubclass(b, Mapping) for b in dict.__bases__] [False] Firstly, as I'm sure you know, if you don't import Mapping from collections the issubclass test fails with a NameError. Secondly, why do you care? Did you get bitten by something? Some error, or worse, silently got wrong results? (Sincere question.) So dict is a subclass of Mapping, even though none of the bases of dict is either Mapping or a subclass of Mapping. Great. I suspect this is another abstraction leak My take on abstraction leaks is when the underlying actuality shows through in a non-ignorable way -- so I ask again, how is this discrepancy making it so you can't ignore it? ~Ethan~ -- http://mail.python.org/mailman/listinfo/python-list
Re: simple games w/o pygame
On 22.12.2010 17:40, William Gill wrote: I am teaching an 11 year old who wants to learn programming. I chose Python, and it is working well. I seem to remember lots of simple script games, like quizzes, number games etc. that would be good for his tutorial. However, now all I can find is more complex games using Pygame. Can anyone help me out here? Recently someone posted this link on the list, which might be interesting: http://inventwithpython.com/index.html Regards Andre -- http://mail.python.org/mailman/listinfo/python-list
Re: compiling Python 2.7.1 with readline module fails on Debian (Virtualbox)
Am 22.12.2010 09:33, schrieb Benedict Verheyen: Hi, i'm trying to compile Python 2.7.1 on Debian (Virtual Box). Compiling end successfully but readline and curses fail to build. I'm working with virtualenv and I install all my packages in $HOME/local. I've downloaded readline, compiled and installed it in $HOME/local, same with ncurses. Both were the latest releases. But somehow, Python isn't able to build them. I get this message: Failed to build these modules: _curses_curses_panelreadline So it does seems to find the modules. I'm not used to dealing with configure, and make so i can't debug much. I first tried this configure line: ./configure --enable-shared --prefix=$HOME/local Next i tried this one: env CPPFLAGS=-I$HOME/local/include LDFLAGS=-L$HOME/local/lib ./configure --enable-shared --prefix=$HOME/local But make yields the same error. Any clues on what I do wrong? The source of ncurses and readline are placed in $HOME/src. Both packages are installed in $HOME/local Thanks for any advice, Regards, Benedict Did you try apt-get install build-essential apt-get build-dep python2.7 before trying to compile ? Anyway, the config.log file is always of special interest. Btw, which Debian release are you running ? If the system is set up correctly it should not be necessary to change env vars to get it built. -- http://mail.python.org/mailman/listinfo/python-list
Re: compiling Python 2.7.1 with readline module fails on Debian (Virtualbox)
are you running make clean for good measure? On Wed, Dec 22, 2010 at 3:33 AM, Benedict Verheyen benedict.verhe...@gmail.com wrote: Hi, i'm trying to compile Python 2.7.1 on Debian (Virtual Box). Compiling end successfully but readline and curses fail to build. I'm working with virtualenv and I install all my packages in $HOME/local. I've downloaded readline, compiled and installed it in $HOME/local, same with ncurses. Both were the latest releases. But somehow, Python isn't able to build them. I get this message: Failed to build these modules: _curses_curses_panelreadline So it does seems to find the modules. I'm not used to dealing with configure, and make so i can't debug much. I first tried this configure line: ./configure --enable-shared --prefix=$HOME/local Next i tried this one: env CPPFLAGS=-I$HOME/local/include LDFLAGS=-L$HOME/local/lib ./configure --enable-shared --prefix=$HOME/local But make yields the same error. Any clues on what I do wrong? The source of ncurses and readline are placed in $HOME/src. Both packages are installed in $HOME/local Thanks for any advice, Regards, Benedict -- http://mail.python.org/mailman/listinfo/python-list -- http://mail.python.org/mailman/listinfo/python-list
Code review request
Hi All, I'm a python newbie so please be kind. I've been reading book after book and have written a script or two but this is my first real program. Just looking for any suggestions and pointers. I've done some work with bash scripts and php (not OOP) a while a go. I'm not a programmer but would like to possibly expand in to it (right now an IT guy). Am I on the right track so far? The program should be documented enough to explain. Created on Tue Dec 21 13:39:41 2010 @author: jason Usage: cmd_drug_testing.py [options]... Will select a random employee from the local database (located in the current directory) and display the name by default. This program (Drug Testing) was written to help select employees for drug testing. Program usage: -h, --help Displays this help info -l, --list-emplysLists all employees in the database -s, --select Select employee for testing -r, --remove-emply Delete employee from database, usage: -d employee_name or id -e, --edit-emply Edit employee data in database, usage: -e employee_name or id field_to_change new_value -i, --insert-emply Insert new employee in database: must fit this format -- id:or '','lastname, firstname', 'email',0 -f Display database name and full path This program was written by, Jason S. For the use of AA. # import our needed modules import sqlite3 as sqlite import sys, getopt #set global vars global cursor global conn def usage(): this just prints the usage in the doc string print __doc__ def dbconnect(sql): handel the connction to the sqlite db dbConnection = sqlite.connect(drug-test.db) #set the cursor cursor = dbConnection.cursor() try: #execute the sql passed from the other funtions and return the results result = cursor.execute(sql) dbConnection.commit() except sqlite.Error, e: result = e.args[0] return result def listEmployees(sql): #list all records in the database listemp = dbconnect(sql) for lst in listemp: print %s, %s, %s, %s % (lst[0],lst[1],lst[2],lst[3]) def selectOneEmployee(sql): #select a random record from the database listemp = dbconnect(sql) for empl in listemp: print empl[0] def removeOneEmployee(sqlchk,sqldel): #delete one employee by ID number chk = dbconnect(sqlchk) if chk.fetchone() != None: #check to make sure the ID is valid in the database emply = dbconnect(sqlchk) emply = emply.fetchall() print trying to remove employee %s % (emply) try: dbconnect(sqldel) except sqlite.Error, e: result = e.args[0] print result else: print Employees ID is invalid, please check the ID number def insertEmployee(sql): #insert a new employee into the database print sql try: dbconnect(sql) except sqlite.Error, e: result = e.args[0] print result def main(argv): The purpose of this program is to select an empployee from this database for random drug testing. This program can also perform maintainance on same database. if argv == []: sql = SELECT name FROM employees ORDER BY RANDOM() LIMIT 1; print The following employee has been selected\n selectOneEmployee(sql) try: #get the options passed by the user opts, args = getopt.getopt(argv, hlsr:e:i:d,[Help,list-emplys,select,remove-emply=,edit-emply=,insert-emply=]) except getopt.GetoptError: usage() sys.exit(2) #check throught the options and respond accordingly for opt, arg in opts: if opt in (-h, --help): usage() sys.exit() elif opt == '-d': global _debug _debug = 1 elif opt in (-l, --list-emplys): sql = select * from employees listEmployees(sql) elif opt in (-s,--select): sql = SELECT name FROM employees ORDER BY RANDOM() LIMIT 1; print The following employee has been selected\n selectOneEmployee(sql) elif opt in (-r,--remove-emply): if arg == : sys.exit(You must provice the ID for the employee to remove) sqlchk = select * from employees where id = \%s\ % (arg) sqldel = delete from employees where id = \%s\ % (arg) removeOneEmployee(sqlchk,sqldel) elif opt in (-i, --insert-emply): sql = insert into employees values(%s) % (arg) insertEmployee(sql) if __name__ == __main__: main(sys.argv[1:]) ## END ### Thanks everyone. Jason ..·º -- http://mail.python.org/mailman/listinfo/python-list
Re: Catching user switching and getting current active user from root on linux
ok, I'll give one more chance. First, to pacify those who hate google groups: What is a good usenet client? second, How should I set up this proxy so that when a connection is made, it request's authentication, and then log's the request, if authentication is not gotten, how do I have it block (or firewall) the request? Furthermore, I would like for the proxy to be squid. So all of the nitty gritty should have to do with squid. -- http://mail.python.org/mailman/listinfo/python-list
Re: Code review request
Am 22.12.2010 19:34, schrieb Jason Staudenmayer: Hi All, I'm a python newbie so please be kind. I've been reading book after book and have written a script or two but this is my first real program. Just looking for any suggestions and pointers. I've done some work with bash scripts and php (not OOP) a while a go. I'm not a programmer but would like to possibly expand in to it (right now an IT guy). Am I on the right track so far? The program should be documented enough to explain. Created on Tue Dec 21 13:39:41 2010 @author: jason Usage: cmd_drug_testing.py [options]... Will select a random employee from the local database (located in the current directory) and display the name by default. This program (Drug Testing) was written to help select employees for drug testing. Program usage: -h, --help Displays this help info -l, --list-emplysLists all employees in the database -s, --select Select employee for testing -r, --remove-emply Delete employee from database, usage: -d employee_name or id -e, --edit-emply Edit employee data in database, usage: -e employee_name or id field_to_change new_value -i, --insert-emply Insert new employee in database: must fit this format -- id:or '','lastname, firstname', 'email',0 -f Display database name and full path This program was written by, Jason S. For the use of AA. # import our needed modules import sqlite3 as sqlite import sys, getopt #set global vars global cursor global conn def usage(): this just prints the usage in the doc string print __doc__ def dbconnect(sql): handel the connction to the sqlite db dbConnection = sqlite.connect(drug-test.db) #set the cursor cursor = dbConnection.cursor() try: #execute the sql passed from the other funtions and return the results result = cursor.execute(sql) dbConnection.commit() except sqlite.Error, e: result = e.args[0] return result def listEmployees(sql): #list all records in the database listemp = dbconnect(sql) for lst in listemp: print %s, %s, %s, %s % (lst[0],lst[1],lst[2],lst[3]) def selectOneEmployee(sql): #select a random record from the database listemp = dbconnect(sql) for empl in listemp: print empl[0] def removeOneEmployee(sqlchk,sqldel): #delete one employee by ID number chk = dbconnect(sqlchk) if chk.fetchone() != None: #check to make sure the ID is valid in the database emply = dbconnect(sqlchk) emply = emply.fetchall() print trying to remove employee %s % (emply) try: dbconnect(sqldel) except sqlite.Error, e: result = e.args[0] print result else: print Employees ID is invalid, please check the ID number def insertEmployee(sql): #insert a new employee into the database print sql try: dbconnect(sql) except sqlite.Error, e: result = e.args[0] print result def main(argv): The purpose of this program is to select an empployee from this database for random drug testing. This program can also perform maintainance on same database. if argv == []: sql = SELECT name FROM employees ORDER BY RANDOM() LIMIT 1; print The following employee has been selected\n selectOneEmployee(sql) try: #get the options passed by the user opts, args = getopt.getopt(argv, hlsr:e:i:d,[Help,list-emplys,select,remove-emply=,edit-emply=,insert-emply=]) except getopt.GetoptError: usage() sys.exit(2) #check throught the options and respond accordingly for opt, arg in opts: if opt in (-h, --help): usage() sys.exit() elif opt == '-d': global _debug _debug = 1 elif opt in (-l, --list-emplys): sql = select * from employees listEmployees(sql) elif opt in (-s,--select): sql = SELECT name FROM employees ORDER BY RANDOM() LIMIT 1; print The following employee has been selected\n selectOneEmployee(sql) elif opt in (-r,--remove-emply): if arg == : sys.exit(You must provice the ID for the employee to remove) sqlchk = select * from employees where id = \%s\ % (arg) sqldel = delete from employees where id = \%s\ % (arg) removeOneEmployee(sqlchk,sqldel) elif opt in (-i, --insert-emply): sql = insert into employees values(%s) % (arg) insertEmployee(sql) if __name__ == __main__: main(sys.argv[1:]) ## END ### Thanks everyone. Jason ..·º Hi Jason, the
RE: Code review request
Hi Jason, There are a couple of things that I noticed: 1. You might want to check out PEP 8 -- a Python style guide. Among other things, some lines are very long and you are not consistent with putting a space after a comma in a list or between arguments in a function call. e.g. opts, args = getopt.getopt(argv, hlsr:e:i:d,[Help,list-emplys,select,remove-emply=,edit-emply=,insert-emply=]) That's 125 characters, not including the indentation! You can break it up and even make it more readable like this: opts, args = getopt.getopt( argv, hlsr:e:i:d, [Help,list-emplys,select,remove-emply=,edit-emply=,insert-emply=] ) but then the embedded list is still too long. It can also be split like this: opts, args = getopt.getopt( argv, hlsr:e:i:d, [Help, list-emplys, select, remove-emply=, edit-emply=, insert-emply=] ) Just do it so that it's easy to read and support. Notice the commas are followed by spaces in the list. In the listEmployees function (check out PEP 8 about naming conventions, while you're at it!) there is one line that could be simpler: print %s, %s, %s, %s % (lst[0],lst[1],lst[2],lst[3]) could be: print %s, %s, %s, %s % tuple(lst[:4]) or if the number of elements could be more or less, you could even do this: for item in lst: print item, which should do the same thing (the trailing comma suppresses the new line) and you'll never have to count the number of items in lst. You also have some statements like: sqlchk = select * from employees where id = \%s\ % (arg) Since a Python list can be enclosed in apostrophes as well as quotations, you can get the same thing without the escapes: sqlchk = 'select * from employees where id = %s' % (arg) Anyway -- just some food for thought. -- Gerald Britton -- http://mail.python.org/mailman/listinfo/python-list
Re: Code review request
Created on Tue Dec 21 13:39:41 2010 @author: jason Usage: cmd_drug_testing.py [options]... Will select a random employee from the local database (located in the current directory) and display the name by default. This program (Drug Testing) was written to help select employees for drug testing. Program usage: -h, --help Displays this help info -l, --list-emplysLists all employees in the database -s, --select Select employee for testing -r, --remove-emply Delete employee from database, usage: -d employee_name or id -e, --edit-emply Edit employee data in database, usage: -e employee_name or id field_to_change new_value -i, --insert-emply Insert new employee in database: must fit this format -- id:or '','lastname, firstname', 'email',0 -f Display database name and full path This program was written by, Jason S. For the use of AA. # import our needed modules import sqlite3 as sqlite import sys, getopt #set global vars global cursor global conn By default, if you bind (assign) to a name inside a function then Python assumes that the name is local to the function, unless you tell it otherwise with global. Using global outside a function has no effect. def usage(): this just prints the usage in the doc string print __doc__ def dbconnect(sql): handel the connction to the sqlite db handel the connction - handle the connection dbConnection = sqlite.connect(drug-test.db) #set the cursor cursor = dbConnection.cursor() try: #execute the sql passed from the other funtions and return the results funtions - functions result = cursor.execute(sql) dbConnection.commit() except sqlite.Error, e: result = e.args[0] return result The Pythonic way is to return a result when successful and raise an exception when unsuccessful. def listEmployees(sql): #list all records in the database listemp = dbconnect(sql) for lst in listemp: print %s, %s, %s, %s % (lst[0],lst[1],lst[2],lst[3]) I wouldn't pass in an SQL string. I'd pass in only the parameters (if any) and hide the SQL details inside the function, something like this: def listEmployees(): # list all records in the database dbConnection = sqlite.connect(DB_NAME) try: try: results = dbConnection.execute(select * from employees) for lst in results: print %s, %s, %s, %s % (lst[0], lst[1], lst[2], lst[3]) except sqlite.Error, e: print ERROR:, e.args[0] finally: dbConnection.close() I'd also be explicit about the names of the fields in the database in case their order changed in a later version. def selectOneEmployee(sql): #select a random record from the database listemp = dbconnect(sql) for empl in listemp: print empl[0] def selectOneEmployee(): # select a random record from the database dbConnection = sqlite.connect(DB_NAME) try: try: results = dbConnection.execute(SELECT name FROM employees ORDER BY RANDOM() LIMIT 1;) print The following employee has been selected\n for empl in results: print empl[0] except sqlite.Error, e: print ERROR:, e.args[0] finally: dbConnection.close() def removeOneEmployee(sqlchk,sqldel): #delete one employee by ID number chk = dbconnect(sqlchk) if chk.fetchone() != None: #check to make sure the ID is valid in the database emply = dbconnect(sqlchk) emply = emply.fetchall() print trying to remove employee %s % (emply) try: dbconnect(sqldel) except sqlite.Error, e: result = e.args[0] print result else: print Employees ID is invalid, please check the ID number sqlchk = sqldel = delete from employees where id = \%s\ % (arg) I'd do: def removeOneEmployee(emplyId): # delete one employee by ID number dbConnection = sqlite.connect(DB_NAME) try: try: # check to make sure the ID is valid in the database results = dbConnection.execute(select * from employees where id = %s, (emplyId, )) if results.fetchone(): print trying to remove employee %s % emplyId dbConnection.execute(delete from employees where id = %s, (emplyId, )) dbConnection.commit() else: print Employees ID is invalid, please check the ID number except sqlite.Error, e:
RE: [SPAM] - Re: Code review request
-Original Message- From: python-list-bounces+jasons=adventureaquarium@python.org [mailto:python-list-bounces+jasons=adventureaquarium@python.org] On Behalf Of Stefan Sonnenberg-Carstens Sent: Wednesday, December 22, 2010 3:24 PM To: python-list@python.org Subject: [SPAM] - Re: Code review request Am 22.12.2010 19:34, schrieb Jason Staudenmayer: Hi All, snip Hi Jason, the program could be more dense. You have several redundant code in there, too. For example, all the *Employee functions basically just call dbconnect and let it execute the sql there. dbconnect in this respect is not a really straight name, as it does more than only connect to a database. You should avoid != None, better is is not None. The program flow is awkward: if argv is empty (better say if not argv), you show one employee, but then continue to parse opts. I think the program would be more readable, if you would just handle the different cases in an if-elseif-else-cascade. The global statement is not needed, But you can also try pylint, which will point some things out: Report 78 statements analysed. snip Thanks for the advice, I'll try to rework some of those issues. I did try the if-elif-else for the getopts but it didn't flow right for some reason (I'll try it again though). Thanks again. Jason ..·º -- http://mail.python.org/mailman/listinfo/python-list
Re: Newbie question about importing modules.
On Wed, Dec 22, 2010 at 7:57 PM, Tim Roberts ti...@probo.com wrote: cronoklee wrote: Thanks Tim - You've certainly shed some light. I presume the PIL installer is setup.py and installation is simple a case of running it? Yes: python setup.py install That scheme is called distutils. Since it became part of the standard Python distribution many years ago, it is now ubiquitous. Is this usually the case for python 'source distribution' packages? Yes. In the Linux world, with a few exceptions, EVERY Python add-on package is installed that way. In the Windows world, most smaller packages come that way. Larger packages will have an MSI installer that does essentially the same thing. Once in a while, you'll download a script that consists only of a single file. That would really be the only exception. Is there a term for packages that do not need to be installed? This might help me search for them in future. I don't think that's the right answer. The installation process is rarely more complicated than copying files to the site-packages directory of your current Python version. The installer can verify dependencies and make sure everything is OK. It's a Good Thing. -- Tim Roberts Thanks a lot Tim - all makes sense. I appreciate the lesson! cronoklee -- http://mail.python.org/mailman/listinfo/python-list
Re: Modifying an existing excel spreadsheet
On Dec 21, 8:56 am, Ed Keith e_...@yahoo.com wrote: I have a user supplied 'template' Excel spreadsheet. I need to create a new excel spreadsheet based on the supplied template, with data filled in. I found the tools herehttp://www.python-excel.org/, andhttp://sourceforge.net/projects/pyexcelerator/. I have been trying to use the former, since the latter seems to be devoid of documentation (not even any docstrings). pyExcelerator is abandonware. Use xlwt instead; it's a bug-fixed/ maintained/enhanced fork of pyExcelerator Read the tutorial that you'll find mentioned on http://www.python-excel.org Join the google group that's also mentioned there; look at past questions, ask some more, ... -- http://mail.python.org/mailman/listinfo/python-list
Re: Catching user switching and getting current active user from root on linux
On 12/22/2010 11:28 AM mpnordland said... ok, I'll give one more chance. ... which probably won't be enough -- this is potentially a huge question you're asking with lots of little bits to put together. I have an installation where I did somthing similar seven-ish years ago using squid, squidguard, blacklists from Université Toulouse in France, python, iptables, sql, php, zope, bash, and who knows what else. It authenticates, logs, tracks, blocks, unblocks, reports activity on an automated In and Out board by user, provides historical stats, automates new user setup and invalidation, and probably more. I put maybe a week or two into it initially, and about the same again over the years adding to it. First, to pacify those who hate google groups: What is a good usenet client? I use thunderbird to access gmane groups. second, How should I set up this proxy so that when a connection is made, it request's authentication, and then log's the request, if authentication is not gotten, how do I have it block (or firewall) the request? Furthermore, I would like for the proxy to be squid. So all of the nitty gritty should have to do with squid. ... and that's where I'd start looking. Check out the current status of Squid to see how much of what you want can be done out of the box. When you hit the limits of what it'll do for you, start writing glue to fill in the puzzle. HTH, Emile -- http://mail.python.org/mailman/listinfo/python-list
Re: Catching user switching and getting current active user from root on linux
On 12/22/2010 2:28 PM, mpnordland wrote: ok, I'll give one more chance. First, to pacify those who hate google groups: What is a good usenet client? Thunderbird is OK for me (I follow about three groups normally). I access the comp.lang.python group vie the Gmane (Main) service, where for some strange resaon best known to the gmane admins it is called gmane.comp.python.general. Ho, hum. I seem to remember Outlook Express was a fairly decent NNTP client as well, and Tim Peters says I'm not just blowing smoke up your ass. second, How should I set up this proxy so that when a connection is made, it request's authentication, and then log's the request, if authentication is not gotten, how do I have it block (or firewall) the request? Furthermore, I would like for the proxy to be squid. So all of the nitty gritty should have to do with squid. I would recommend you take a look at the Spambayes code, which does all that sort of stuff apparently quite reliably. If you aren't yet proficient enough with Python to understand the code on your own look for a Python Meetup or a local or regional conference to meet people who will helpyou answer your questions. Increasingly there are workspaces like HacDC springing up to give people access to advanced technologies at everyday prices. You could look for such a group locally. There's lots of energy from people once they realise that what gets built can help them. Squid is a different matter. For that, probably if you go on an IRC channel (freenode.net is what I use, but others have their favorites). Maybe #squid? regards Steve -- Steve Holden +1 571 484 6266 +1 800 494 3119 PyCon 2011 Atlanta March 9-17 http://us.pycon.org/ See Python Video! http://python.mirocommunity.org/ Holden Web LLC http://www.holdenweb.com/ -- http://mail.python.org/mailman/listinfo/python-list
Python Web App
Anybody know where I can find a Python Development Environment in the form of a web app for use with Chrome OS. I have been looking for a few days and all i have been able to find is some old discussions with python developers talking about they will want one for the OS to be a success with them. -- http://mail.python.org/mailman/listinfo/python-list
Re: Question regarding Higher-Order-Programming in Python
Mark Fink m...@mark-fink.de writes:
so far I have never noticed chain.from_iterable, but many thanks to
you Peter, I have now a beautiful solution to this problem.
from itertools import chain
comb = it.combinations(dims, 2)
l = chain.from_iterable(it.imap(get_products, comb))
You can also write this as:
l = (p for c in comb for p in get_products(c))
l.next()
[('special', '+'), ('number', 1)]
l.next()
[('special', '+'), ('number', 2)]
Also in your original post you define get_products:
def get_products(keys):
... # helper to get products from keys in the following form:
... # [('bold', True), ('color', 'black')]
... values = itemgetter(*keys)(dims)
... product = it.product(*values)
... return map(partial(zip, keys), product)
...
You could define it as e.g.
def get_products(keys):
key_values = [[(k, v) for v in values] for k in keys]
return it.product(*key_values)
But maybe for some reason you are trying to avoid list comprehensions
and generator expressions?
--
Arnaud
--
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Re: How to pop the interpreter's stack?
On Dec 22, 8:52 am, kj no.em...@please.post wrote: In mailman.65.1292517591.6505.python-l...@python.org Robert Kern robert.k...@gmail.com writes: Obfuscating the location that an exception gets raised prevents a lot of debugging... The Python interpreter does a lot of that obfuscation already, and I find the resulting tracebacks more useful for it. An error message is only useful to a given audience if that audience can use the information in the message to modify what they are doing to avoid the error. So when the audience files a bug report it's not useful for them to include the whole traceback? It is of no use (certainly no *immediate* use) to this audience to see tracebacks that go deep into code that they don't know anything about and cannot change. Seriously, quit trying to do the user favors. There's nothing that pisses me off than a self-important developer thinking he knows what the user wants more than the user does. Carl Banks -- http://mail.python.org/mailman/listinfo/python-list
Re: Catching user switching and getting current active user from root on linux
On Mon, 20 Dec 2010 20:35:54 -0500, Steve Holden wrote: On 12/20/2010 12:54 PM, mpnordland wrote: I give up, I will never try to use a usenet group again. For the ones of you who tried to help thank you. You helped to identify some of my troubles, as for you @usernet, you are a troll Don't give up after one experience. Usenet can be really useful as long as you know who to listen to and who to ignore ... More importantly, Usenet can be very useful so long as you know how to ask smart questions. If you insist on asking stupid questions, you will rapidly get disillusioned: people will either ignore you, abuse you, or give you helpful advice that you don't want to hear. -- Steven -- http://mail.python.org/mailman/listinfo/python-list
Re: Catching user switching and getting current active user from root on linux
Am 22.12.2010 20:28, schrieb mpnordland: ok, I'll give one more chance. First, to pacify those who hate google groups: What is a good usenet client? second, How should I set up this proxy so that when a connection is made, it request's authentication, and then log's the request, if authentication is not gotten, how do I have it block (or firewall) the request? Furthermore, I would like for the proxy to be squid. So all of the nitty gritty should have to do with squid. Just install Squid, enable user authentication and grant access only to authenticated people. Now, configure logrotated and tell to rotate logs every day/week/month (your mileage will vary). After rotating run a program such as webalizer to get stats (even on a per user basis). If you have smart guys under your users, set up a) a transparent proxy intercepting http/https requests or b) set up a iptables firewall with redirection to the squid port. There are many, many, many how-to documents on the net describing exactly what you want to do. A first starting point could be http://www.comfsm.fm/computing/squid/FAQ.html And your problems are solved a long time ago: http://www.faqs.org/docs/Linux-mini/TransparentProxy.html And, the most important thing: Check your local laws for this intention. Some, like our german law, require these things to be under clear rules. Cheers -- http://mail.python.org/mailman/listinfo/python-list
Re: Trying to parse a HUGE(1gb) xml file
On 12/20/2010 12:33 PM, Adam Tauno Williams wrote: On Mon, 2010-12-20 at 12:29 -0800, spaceman-spiff wrote: I need to detect them then for each 1, i need to copy all the content b/w the element's start end tags create a smaller xml file. Yep, do that a lot; via iterparse. 1. Can you point me to some examples/samples of using SAX, especially , ones dealing with really large XML files. I've just subclassed HTMLparser for this. It's slow, but 100% Python. Using the SAX parser is essentially equivalent. I'm processing multi-gigabyte XML files and updating a MySQL database, so I do need to look at all the entries, but don't need a parse tree of the XML. SaX is equivalent to iterparse (iterpase is a way, to essentially, do SaX-like processing). Iterparse does try to build a tree, although you can discard the parts you don't want. If you can't decide whether a part of the XML is of interest until you're deep into it, an iterparse approach may result in a big junk tree. You have to keep clearing the root element to discard that. I provided an iterparse example already. See the Read_Rows method in http://coils.hg.sourceforge.net/hgweb/coils/coils/file/62335a211fda/src/coils/foundation/standard_xml.py I don't quite see the point of creating a class with only static methods. That's basically a verbose way to create a module. 2.This brings me to another q. which i forgot to ask in my OP(original post). Is simply opening the file, using reg ex to look for the element i need, a *good* approach ? No. If the XML file has a very predictable structure, that may not be a bad idea. It's not very general, but if you have some XML file that's basically fixed format records using XML to delimit the fields, pounding on the thing with a regular expression is simple and fast. John Nagle -- http://mail.python.org/mailman/listinfo/python-list
Re: issubclass(dict, Mapping)
On 12/22/2010 9:20 AM, kj wrote:
from collections import Mapping
Documented as an *ABSTRACT* base class. ABCs were added in 3.0 and
backparted to 2.7. One can be quite competant in Python completely
ignoring ABCs.
issubclass(dict, Mapping)
True
Yes, dict is a concrete Mapping class. I suppose we could have instead
added a new builtin function 'isconcretetizationof' but is seemed easier
to reuse issubclass for the test. Most people have no problem with that.
dict.__bases__
(type 'object',)
The one and only *CONCRETE* base class. In 3.x, all classes are
subclasses of object, which simplifies the class model a bit.
[issubclass(b, Mapping) for b in dict.__bases__]
[False]
So dict is a subclass of Mapping, even though none of the bases of
dict is either Mapping or a subclass of Mapping. Great.
Right. dict is direct concrete Mapping implementation and not subclassed
from one.
The main reason for introducing ABCs was to make it easier to test
whether an object passed to a function is an instance of a possibly
unknown or yet-to-be-written class in an abstract category, which has a
certain api or interface. The actual usage of an ABC would be more like
this:
from collections import Mapping
def f(m):
if not isinstance(m, Mapping):
raise ValueError('input is not a mapping')
else: return True
f(dict())
# True
f([])
# produces
Traceback (most recent call last):
File pyshell#8, line 1, in module
f([])
File pyshell#6, line 3, in f
raise ValueError('input is not a mapping')
ValueError: input is not a mapping
--
Terry Jan Reedy
--
http://mail.python.org/mailman/listinfo/python-list
Toy http server
Sorry, this one is cross post.
I posted my question below some time ago to then jython ml, because this
hit me first with jython.
Anyway, time passed, problem not solved.
So, I'd like to know if some of you know where my error lies:
Hi all,
I've played around with some code-kata of mine from the past.
It's a toy http server:
import socket
import select
import sys
import time
srv = socket.socket(socket.AF_INET,socket.SOCK_STREAM)
srv.setblocking(0)
srv.setsockopt(socket.SOL_SOCKET,socket.SO_REUSEADDR,True) # Not sure if
this is needed. I only remember I've started once for some reason.
Commenting out does no change
if srv:
srv.bind(('',8080))
srv.setblocking(0)
srv.listen(5)
conns = [srv]
buffers = {}
while True:
reader,writer,failed = select.select(conns,conns,[],1)
if failed:
sys.exit(1)
if srv in reader:
client,(ip,port) = srv.accept()
client.setblocking(False)
conns += [client]
for r in reader:
if r is not srv:
data = r.recv(1024)
if not data:
conns.remove(r)
else:
if r in buffers:
buffers[r] += data
else:
buffers[r] = data
for w in writer:
if w is not srv:
if w in buffers and buffers[w][-2:] == '\r\n':
msg = 'HTTP/1.0 200 OK\r\nServer:
Jython/2.5\r\nContent-type: text/plain\r\n\r\nThe answer is: 42\r\n'
w.send(msg)
w.close() # THIS ONLY WORKS WHEN THIS LINE IS PRESENT
conns.remove(w) # AND THEN THIS IS MUST
buffers[w] = ''
But today I was asking myself why I should always close the socket, and
if wouldn't be more efficient if
I let it open.
To make a long story short: it does not work.
If I comment out the lines with the comment all upper case,
jython consumes one core in my laptop completely and ab.exe from apache
bails out after a while.
Changing send() to sendall() did not do the trick.
I've searched the web and did not find anything meaningful.
Perhaps someone here can switch the light on.
--
http://mail.python.org/mailman/listinfo/python-list
Re: issubclass(dict, Mapping)
On Wed, 22 Dec 2010 14:20:51 +, kj wrote: Here's another example, fresh from today's crop of wonders: (v. 2.7.0) from collections import Mapping issubclass(dict, Mapping) True dict.__bases__ (type 'object',) [issubclass(b, Mapping) for b in dict.__bases__] [False] So dict is a subclass of Mapping, even though none of the bases of dict is either Mapping or a subclass of Mapping. Great. Yes. So what? (1) What *actual* problem does this cause you? (2) Do you have an example of code that breaks because of this? (3) Do you understand that since the introduction of ABC (abstract base classes) in Python 2.6 (I think), isinstance and issubclass checks are performed cooperatively? The instance or class are asked if they wish to be known as an instance/subclass of the second argument. Classes can register themselves as subclasses of (say) Mapping without sharing any actual code with Mapping. This is a good thing, and the problem isn't that the abstraction leaks, as you believe, but the opposite: you're *ignoring* the abstraction and looking for concrete details that may or may not exist. I fear that you have fundamentally misunderstood the concept of leaky abstraction. It does not mean, as you seem to think, that some concrete implementation detail differs between two classes (or functions). It means that some difference in behaviour is exposed, that difference being irrelevant to the abstraction but nevertheless important in some other sense. A contrived example: class MyList(list): def __len__(self): import time time.sleep(360) return list.__len__(self) MyList can be used anywhere a regular list can be used. Functionally the two are identical. The abstraction is that MyList is the same as list. But the leak is that len(MyList()) is *incredibly* slow. Coming back to Mapping: Abstraction: issubclass(dict, Mapping) One possible concrete implementation detail of how issubclass is implemented: any(base is Mapping for base in dict.__bases__) The statement dict is a subclass of Mapping is about an abstract relationship. It's not necessarily a statement about __bases__. To give an analogy, if you insist on doing DNA testing to determine whether a boy is a son of a man, you're going to be confused and distressed every time you find fathers whose sons are genetically unrelated to them. -- Steven -- http://mail.python.org/mailman/listinfo/python-list
Re: Code review request
On 12/22/2010 10:34 AM, Jason Staudenmayer wrote: Hi All, I'm a python newbie so please be kind. I've been reading book after book and have written a script or two but this is my first real program. Just looking for any suggestions and pointers. I've done some work with bash scripts and php (not OOP) a while a go. I'm not a programmer but would like to possibly expand in to it (right now an IT guy). Am I on the right track so far? The program should be documented enough to explain. Created on Tue Dec 21 13:39:41 2010 @author: jason Usage: cmd_drug_testing.py [options]... Will select a random employee from the local database (located in the current directory) and display the name by default. This program (Drug Testing) was written to help select employees for drug testing. Program usage: -h, --help Displays this help info -l, --list-emplysLists all employees in the database -s, --select Select employee for testing -r, --remove-emply Delete employee from database, usage: -d employee_name or id -e, --edit-emply Edit employee data in database, usage: -e employee_name or id field_to_change new_value -i, --insert-emply Insert new employee in database: must fit this format -- id:or '','lastname, firstname', 'email',0 -f Display database name and full path This program was written by, Jason S. For the use of AA. # import our needed modules import sqlite3 as sqlite import sys, getopt #set global vars global cursor global conn def usage(): this just prints the usage in the doc string print __doc__ def dbconnect(sql): handel the connction to the sqlite db dbConnection = sqlite.connect(drug-test.db) #set the cursor cursor = dbConnection.cursor() try: #execute the sql passed from the other funtions and return the results result = cursor.execute(sql) dbConnection.commit() except sqlite.Error, e: result = e.args[0] return result def listEmployees(sql): #list all records in the database listemp = dbconnect(sql) for lst in listemp: print %s, %s, %s, %s % (lst[0],lst[1],lst[2],lst[3]) def selectOneEmployee(sql): #select a random record from the database listemp = dbconnect(sql) for empl in listemp: print empl[0] def removeOneEmployee(sqlchk,sqldel): #delete one employee by ID number chk = dbconnect(sqlchk) if chk.fetchone() != None: #check to make sure the ID is valid in the database emply = dbconnect(sqlchk) emply = emply.fetchall() print trying to remove employee %s % (emply) try: dbconnect(sqldel) except sqlite.Error, e: result = e.args[0] print result else: print Employees ID is invalid, please check the ID number def insertEmployee(sql): #insert a new employee into the database print sql try: dbconnect(sql) except sqlite.Error, e: result = e.args[0] print result def main(argv): The purpose of this program is to select an empployee from this database for random drug testing. This program can also perform maintainance on same database. if argv == []: sql = SELECT name FROM employees ORDER BY RANDOM() LIMIT 1; print The following employee has been selected\n selectOneEmployee(sql) try: #get the options passed by the user opts, args = getopt.getopt(argv, hlsr:e:i:d,[Help,list-emplys,select,remove-emply=,edit-emply=,insert-emply=]) except getopt.GetoptError: usage() sys.exit(2) #check throught the options and respond accordingly for opt, arg in opts: if opt in (-h, --help): usage() sys.exit() elif opt == '-d': global _debug _debug = 1 elif opt in (-l, --list-emplys): sql = select * from employees listEmployees(sql) elif opt in (-s,--select): sql = SELECT name FROM employees ORDER BY RANDOM() LIMIT 1; print The following employee has been selected\n selectOneEmployee(sql) elif opt in (-r,--remove-emply): if arg == : sys.exit(You must provice the ID for the employee to remove) sqlchk = select * from employees where id = \%s\ % (arg) sqldel = delete from employees where id = \%s\ % (arg) removeOneEmployee(sqlchk,sqldel) elif opt in (-i, --insert-emply): sql = insert into employees values(%s) % (arg) insertEmployee(sql) if __name__ == __main__: main(sys.argv[1:]) ## END ### Thanks everyone. Jason ..·º you might consider
Re: Trying to parse a HUGE(1gb) xml file
Am 20.12.2010 20:34, schrieb spaceman-spiff:
Hi c.l.p folks
This is a rather long post, but i wanted to include all the details everything i
have tried so far myself, so please bear with me read the entire boringly long
post.
I am trying to parse a ginormous ( ~ 1gb) xml file.
0. I am a python xml n00b, s have been relying on the excellent beginner book
DIP(Dive_Into_Python3 by MP(Mark Pilgrim) Mark , if u are readng this, you are AWESOME
so is your witty humorous writing style)
1. Almost all exmaples pf parsing xml in python, i have seen, start off with
these 4 lines of code.
import xml.etree.ElementTree as etree
tree = etree.parse('*path_to_ginormous_xml*')
root = tree.getroot() #my huge xml has 1 root at the top level
print root
2. In the 2nd line of code above, as Mark explains in DIP, the parse function
builds returns a tree object, in-memory(RAM), which represents the entire
document.
I tried this code, which works fine for a small ( ~ 1MB), but when i run this
simple 4 line py code in a terminal for my HUGE target file (1GB), nothing
happens.
In a separate terminal, i run the top command, i can see a python process,
with memory (the VIRT column) increasing from 100MB , all the way upto 2100MB.
I am guessing, as this happens (over the course of 20-30 mins), the tree
representing is being slowly built in memory, but even after 30-40 mins,
nothing happens.
I dont get an error, seg fault or out_of_memory exception.
My hardware setup : I have a win7 pro box with 8gb of RAM intel core2 quad
cpuq9400.
On this i am running sun virtualbox(3.2.12), with ubuntu 10.10 as guest os, with
23gb disk space 2gb(2048mb) ram, assigned to the guest ubuntu os.
3. I also tried using lxml, but an lxml tree is much more expensive, as it
retains more info about a node's context, including references to it's parent.
[http://www.ibm.com/developerworks/xml/library/x-hiperfparse/]
When i ran the same 4line code above, but with lxml's elementree ( using the
import below in line1of the code above)
import lxml.etree as lxml_etree
i can see the memory consumption of the python process(which is running the code)
shoot upto ~ 2700mb then, python(or the os ?) kills the process as it nears
the total system memory(2gb)
I ran the code from 1 terminal window (screenshot :http://imgur.com/ozLkB.png)
ran top from another terminal (http://imgur.com/HAoHA.png)
4. I then investigated some streaming libraries, but am confused - there is
SAX[http://en.wikipedia.org/wiki/Simple_API_for_XML] , the iterparse
interface[http://effbot.org/zone/element-iterparse.htm]
Which one is the best for my situation ?
Any all code_snippets/wisdom/thoughts/ideas/suggestions/feedback/comments/ of
the c.l.p community would be greatly appreciated.
Plz feel free to email me directly too.
thanks a ton
cheers
ashish
email :
ashish.makani
domain:gmail.com
p.s.
Other useful links on xml parsing in python
0. http://diveintopython3.org/xml.html
1.
http://stackoverflow.com/questions/1513592/python-is-there-an-xml-parser-implemented-as-a-generator
2. http://codespeak.net/lxml/tutorial.html
3.
https://groups.google.com/forum/?hl=enlnk=gstq=parsing+a+huge+xml#!topic/comp.lang.python/CMgToEnjZBk
4. http://www.ibm.com/developerworks/xml/library/x-hiperfparse/
5.http://effbot.org/zone/element-index.htm
http://effbot.org/zone/element-iterparse.htm
6. SAX : http://en.wikipedia.org/wiki/Simple_API_for_XML
Normally (what is normal, anyway?) such files are auto-generated,
and are something that has a apparent similarity with a database query
result, encapsuled in xml.
Most of the time the structure is same for every row thats in there.
So, a very unpythonic but fast, way would be to let awk resemble the
records and write them in csv format to stdout.
then pipe that to your python cruncher of choice and let it do the hard
work.
The awk part can be done in python, anyway, so could skip that.
And take a look at xmlsh.org, they offer tools for the command line,
like xml2csv. (Need java, btw).
Cheers
--
http://mail.python.org/mailman/listinfo/python-list
Re: simple games w/o pygame
On Wed, 22 Dec 2010 16:40:21 -, William Gill nore...@domain.invalid wrote: I am teaching an 11 year old who wants to learn programming. I chose Python, and it is working well. I seem to remember lots of simple script games, like quizzes, number games etc. that would be good for his tutorial. However, now all I can find is more complex games using Pygame. Can anyone help me out here? Try the numbered worksheets from the Livewires course: http://www.livewires.org.uk/python/home They are aimed at 12-15 year olds, but an 11 year old should be able to cope. -- Rhodri James *-* Wildebeest Herder to the Masses -- http://mail.python.org/mailman/listinfo/python-list
Generator question
So I have a generator, either as a free function or in a class and I want to generate objects that are initialized from the generated things. def generator(): for whatever: yield something class Object(): def __init__(self): self.data = # the next thing from generator I have not been able to implement this elegantly. For external reasons the following syntax is unacceptable: for g in generator(): ob = Object(g) I really want to be able to write Object() in any location and get a properly initialized object. Hints appreciated. Victor. -- Victor Eijkhout -- eijkhout at tacc utexas edu -- http://mail.python.org/mailman/listinfo/python-list
Re: How to pop the interpreter's stack?
In 1f47c36d-a509-4d05-ba79-62b4a534b...@j19g2000prh.googlegroups.com Carl Banks pavlovevide...@gmail.com writes: On Dec 22, 8:52=A0am, kj no.em...@please.post wrote: In mailman.65.1292517591.6505.python-l...@python.org Robert Kern rober= t.k...@gmail.com writes: Obfuscating the location that an exception gets raised prevents a lot of debugging... The Python interpreter does a lot of that obfuscation already, and I find the resulting tracebacks more useful for it. An error message is only useful to a given audience if that audience can use the information in the message to modify what they are doing to avoid the error. =A0It is of no use (certainly no *immediate* use) to this audience to see tracebacks that go deep into code that they don't know anything about and cannot change. So when the audience files a bug report it's not useful for them to include the whole traceback? Learn to read, buster. I wrote *immediate* use. ~kj -- http://mail.python.org/mailman/listinfo/python-list
Re: Generator question
On 12/22/2010 3:15 PM Victor Eijkhout said... So I have a generator, either as a free function or in a class and I want to generate objects that are initialized from the generated things. def generator(): for whatever: yield something class Object(): def __init__(self): How about change to def __init__(self, data=generator()): self.data = # the next thing from generator then... self.data = data.next()# the next thing from generator HTH, Emile I have not been able to implement this elegantly. For external reasons the following syntax is unacceptable: for g in generator(): ob = Object(g) I really want to be able to write Object() in any location and get a properly initialized object. Hints appreciated. Victor. -- http://mail.python.org/mailman/listinfo/python-list
Re: Generator question
On Wed, Dec 22, 2010 at 3:15 PM, Victor Eijkhout s...@sig.for.address wrote: So I have a generator, either as a free function or in a class and I want to generate objects that are initialized from the generated things. def generator(): for whatever: yield something class Object(): def __init__(self): self.data = # the next thing from generator I have not been able to implement this elegantly. For external reasons the following syntax is unacceptable: for g in generator(): ob = Object(g) I really want to be able to write Object() in any location and get a properly initialized object. Hints appreciated. Victor. -- Victor Eijkhout -- eijkhout at tacc utexas edu -- http://mail.python.org/mailman/listinfo/python-list You likely want a class variable: #!/usr/bin/python def generator(): i = 0 while True: yield i i += 1 class Object: gen = generator() def __init__(self): self.data = Object.gen.next() def __str__(self): return str(self.data) o1 = Object() o2 = Object() o3 = Object() print o1 print o2 print o3 -- http://mail.python.org/mailman/listinfo/python-list
using python ftp
Hi, i was wondering whether someone can point me whether the following already exists. I want to connect to a server , download various files (for whose name i want to be able to use a wildcard), and store those files in a given location on the hard drive. If the file already exists i do not want to download it. This seems fairly trivial and i would assume that there should be some sort of implementation that does this easily but i didn't find anything googling it. Otherwise i was going to do it by hand using ftplib: 1) connect to server, 2) change to directory on server 3) get listing 4) match the file pattern i want to the listing 5) check if file already exists 6) download file if matched and doesn't exist Can anyone offer any advice whether this already done somewhere? thanks matt -- http://mail.python.org/mailman/listinfo/python-list
Re: Python Web App
I am creating one, is on test, what kind of app do you want create? 2010/12/22, Sean secr...@gmail.com: Anybody know where I can find a Python Development Environment in the form of a web app for use with Chrome OS. I have been looking for a few days and all i have been able to find is some old discussions with python developers talking about they will want one for the OS to be a success with them. -- http://mail.python.org/mailman/listinfo/python-list -- Enviado desde mi dispositivo móvil Diego I. Hidalgo D. -- http://mail.python.org/mailman/listinfo/python-list
Re: Python Web App
On 2010-12-22, Sean secr...@gmail.com wrote: Anybody know where I can find a Python Development Environment in the form of a web app for use with Chrome OS. I have been looking for a few days and all i have been able to find is some old discussions with python developers talking about they will want one for the OS to be a success with them. Personally, I think a web app based IDE would be ghastly; but, you might have a look at Mozilla Skywriter (formerly Bespin): https://mozillalabs.com/skywriter/ -- http://mail.python.org/mailman/listinfo/python-list
Re: Python Web App
Why grashtly? 2010/12/22, Tim Harig user...@ilthio.net: On 2010-12-22, Sean secr...@gmail.com wrote: Anybody know where I can find a Python Development Environment in the form of a web app for use with Chrome OS. I have been looking for a few days and all i have been able to find is some old discussions with python developers talking about they will want one for the OS to be a success with them. Personally, I think a web app based IDE would be ghastly; but, you might have a look at Mozilla Skywriter (formerly Bespin): https://mozillalabs.com/skywriter/ -- http://mail.python.org/mailman/listinfo/python-list -- Enviado desde mi dispositivo móvil Diego I. Hidalgo D. -- http://mail.python.org/mailman/listinfo/python-list
Re: how to handle output generated after execution of command/script on host unix machine?
On Sun, Dec 19, 2010 at 11:38 PM, Darshak Bavishi
bavishi.dars...@gmail.com wrote:
Hi Experts,
I am still struggling with handling output generated after execution of
command/script on host unix machine using windows client machine
ssh code :
import sys
import datetime
import time
# setup logging
paramiko.util.log_to_file('darshak_simple.log')
ssh=paramiko.SSHClient()
ssh.set_missing_host_key_policy(paramiko.AutoAddPolicy())
ssh.connect(*,username=,password=)
try:
stdin,stdout,stderr=ssh.exec_command(BsPlSMProbe -f node -d
/var/log/Darshak/3.txt ) // output of this command will be store in
/var/log/Darshak/ in remote machine
except:
{Issue is
files are generating but remaining blank pls pls help me out of this}
print check
time.sleep(10)
print stdout.readlines()
a=stdout.readlines()
print 1
ssh.close()
#print stdout.readlines()
Issue is files are generating but remaining blank pls pls help me out of
this
--
BR
Darshak Bavishi
--
BR
Darshak Bavishi
--
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I've never used paramiko, but I have done some python+ssh.
1) Are you wanting the output from BsPlSMProbe to go to
/var/log/Darshak/3.txt or your print stdout.readlines()? If you need
both, you'd probably better get a tee in there.
2) If /var/log/Darshak/3.txt is coming up empty, it could mean that
BsPlSMProbe simply produces no output. What if you ssh into the
server interactively (perhaps using openssh or putty), and your
command from there, as the same user, with the same options?
3) If you want errors as well as normal output in the same place, try
a 21 in your shell command, assuming you're using sh/ksh/bash (POSIX
shell). You can tell what shell you're in with echo $SHELL.
4) If paramiko allows you to access the exit status of the command,
you probably should retrieve that, not just stdout (and stderr).
Conventionally, if the exit status is 0, things are fine, if they're
nonzero, something's wrong - the oppose of what you see in most other
languages that treat integers as booleans, because there are usually
more ways things can fail than succeed. In fact, strictly speaking,
the presence or absence of text on stderr is not a good indication of
an error, compared to checking the exit status.
HTH
--
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general problem when subclassing a built-in class
Suppose that you want to implement a subclass of built-in class, to
meet some specific design requirements.
Where in the Python documentation can one find the information
required to determine the minimal[1] set of methods that one would
need to override to achieve this goal?
In my experience, educated guesswork doesn't get one very far with
this question.
Here's a *toy example*, just to illustrate this last point.
Suppose that one wants to implement a subclass of dict, call it
TSDict, to meet these two design requirements:
1. for each one of its keys, an instance of TSDict should keep a
timestamp (as given by time.time, and accessible via the new method
get_timestamp(key)) of the last time that the key had a value
assigned to it;
2. other than the added capability described in (1), an instance
of TSDict should behave *exactly* like a built-in dictionary.
In particular, we should be able to observe behavior like this:
d = TSDict((('uno', 1), ('dos', 2)), tres=3, cuatro=4)
d['cinco'] = 5
d
{'cuatro': 4, 'dos': 2, 'tres': 3, 'cinco': 5, 'uno': 1}
d.get_timestamp('uno')
1293046586.644436
OK, here's one strategy, right out of OOP 101:
#---
from time import time
class TSDict(dict):
def __setitem__(self, key, value):
# save the value and timestamp for key as a tuple;
# see footnote [2]
dict.__setitem__(self, key, (value, time()))
def __getitem__(self, key):
# extract the value from the value-timestamp pair and return it
return dict.__getitem__(self, key)[0]
def get_timestamp(self, key):
# extract the timestamp from the value-timestamp pair and return it
return dict.__getitem__(self, key)[1]
#---
This implementation *should* work (again, at least according to
OOP 101), but, in fact, it doesn't come *even close*:
d = TSDict((('uno', 1), ('dos', 2)), tres=3, cuatro=4)
d['cinco'] = 5
d
{'cuatro': 4, 'dos': 2, 'tres': 3, 'cinco': (5, 1293059516.942985), 'uno': 1}
d.get_timestamp('uno')
Traceback (most recent call last):
File stdin, line 1, in module
File /tmp/tsdict.py, line 23, in get_timestamp
return dict.__getitem__(self, key)[1]
TypeError: 'int' object is not subscriptable
From the above you can see that TSDict fails at *both* of the design
requirements listed above: it fails to add a timestamp to all keys in
the dictionary (e.g. 'uno', ..., 'cuatro' didn't get a timestamp), and
get_timestamp bombs; and it also fails to behave in every other
respect exactly like a built-in dict (e.g., repr(d) reveals the
timestamps and how they are kept).
So back to the general problem: to implement a subclass of a built-in
class to meet a given set of design specifications. Where is the
documentation needed to do this without guesswork?
Given results like the one illustrated above, I can think of only two
approaches (other than scrapping the whole idea of subclassing a
built-in class in the first place):
1) Study the Python C source code for the built-in class in the hopes
of somehow figuring out what API methods need to be overridden;
2) Through blind trial-and-error, keep trying different implementation
strategies and/or keep overriding additional built-in class methods
until the behavior of the resulting subclass approximates
sufficiently the design specs.
IMO, both of these approaches suck. Approach (1) would take *me*
forever, since I don't know the first thing about Python's internals,
and even if I did, going behind the documented API like that would
make whatever I implement very likely to break with future releases of
Python. Approach (2) could also take a very long time (probably much
longer than the implementation would take if no guesswork was
involved), but worse than that, one would have little assurance that
one's experimentation has truly uncovered all the necessary details;
IME, programming-by-guesswork leads to numerous and often nasty bugs.
Is there any other way?
TIA!
~kj
[1] The minimal bit in the question statement is just another way of
specifying a maximal reuse of the built-in's class code.
[2] For this example, I've accessed the parent's methods directly
through dict rather than through super(TSDict, self), just to keep
the code as uncluttered as possible, but the results are the same
if one uses super.
--
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Python programming
Dear python-list@python.org, Thank you for taking the time to listen to my request. I#39;m a beginner programmer and I se python 2.6. I am making a program that needs a command that can check if a value is in a list. For example to check whether 5 is in [2, 6, 5,]. Thank you for hearing my request. Maurice Shih -- http://mail.python.org/mailman/listinfo/python-list
Re: Python programming
If you're just starting out, look at the Python tutorial http://docs.python.org/tutorial/index.html This question is answered in the tutorial- specifically in http://docs.python.org/tutorial/datastructures.html#more-on-conditions Also, there's a separate list, the tu...@python.org , for people just learning python. http://www.python.org/mailman/listinfo/tutor On Wed, Dec 22, 2010 at 8:22 PM, Maurice Shih rockitout...@yahoo.com wrote: Dear python-list@python.org, Thank you for taking the time to listen to my request. I'm a beginner programmer and I se python 2.6. I am making a program that needs a command that can check if a value is in a list. For example to check whether 5 is in [2, 6, 5,]. Thank you for hearing my request. Maurice Shih -- http://mail.python.org/mailman/listinfo/python-list -- http://mail.python.org/mailman/listinfo/python-list
Re: Python programming
The most Pythonic ways of checking if a value is within a list is to use the in keyword, for example, using your data - 5 in [2, 6, 5] Which will return True, as 5 is in the list. You can then use this in the following generic way - if variable in list: do_things Where variable is the varible you wish to seek, and the list is the list you wish to search. Might I also suggest that you use the *tut...@*python*.org mailing list, where people are perhaps more ready to handle this sort of question. -- http://mail.python.org/mailman/listinfo/python-list
Re: issubclass(dict, Mapping)
In 4d127d5e$0$29997$c3e8da3$54964...@news.astraweb.com Steven D'Aprano steve+comp.lang.pyt...@pearwood.info writes: On Wed, 22 Dec 2010 14:20:51 +, kj wrote: Here's another example, fresh from today's crop of wonders: (v. 2.7.0) from collections import Mapping issubclass(dict, Mapping) True dict.__bases__ (type 'object',) [issubclass(b, Mapping) for b in dict.__bases__] [False] So dict is a subclass of Mapping, even though none of the bases of dict is either Mapping or a subclass of Mapping. Great. Yes. So what? That's being deliberately obtuse. The situation described goes smack against standard OOP semantics, which would be fine if all this stuff was documented clearly and reasonably, i.e. in one (preferably official) place rather than scattered over a bazillion separate documents, PEP this, module that, GvR musing #42, etc. Let's just say that I'm looking forward to the end to these surprises. ~kj -- http://mail.python.org/mailman/listinfo/python-list
Re: Toy http server
On 22/12/2010 22:34, Stefan Sonnenberg-Carstens wrote: Sorry, this one is cross post. I posted my question below some time ago to then jython ml, because this hit me first with jython. Anyway, time passed, problem not solved. So, I'd like to know if some of you know where my error lies: [snip] What happens if the conns list contains a writer that's ready? The select function returns immediately with that writer in the writer list. If it's not srv then nothing is done with it, so execution just loops back to the select function with that writer still in the conns list, and the select function then returns immediately with that writer in the writer list again. Infinite loop! -- http://mail.python.org/mailman/listinfo/python-list
Re: Python Web App
I am wanting to learn python and I am test a Chrome OS notebook at the same time so I need something that will atleast tell me if I have any syntax errors. Although the more features the better that way learning is an easier experience. On Dec 22, 7:05 pm, Hidura hid...@gmail.com wrote: I am creating one, is on test, what kind of app do you want create? 2010/12/22, Sean secr...@gmail.com: Anybody know where I can find a Python Development Environment in the form of a web app for use with Chrome OS. I have been looking for a few days and all i have been able to find is some old discussions with python developers talking about they will want one for the OS to be a success with them. -- http://mail.python.org/mailman/listinfo/python-list -- Enviado desde mi dispositivo móvil Diego I. Hidalgo D. -- http://mail.python.org/mailman/listinfo/python-list
Re: Python Web App
Forgot to point out that Chrome OS has no local storage accessable to the user. Hence why I need a web based solution. On Dec 22, 8:51 pm, Sean secr...@gmail.com wrote: I am wanting to learn python and I am test a Chrome OS notebook at the same time so I need something that will atleast tell me if I have any syntax errors. Although the more features the better that way learning is an easier experience. On Dec 22, 7:05 pm, Hidura hid...@gmail.com wrote: I am creating one, is on test, what kind of app do you want create? 2010/12/22, Sean secr...@gmail.com: Anybody know where I can find a Python Development Environment in the form of a web app for use with Chrome OS. I have been looking for a few days and all i have been able to find is some old discussions with python developers talking about they will want one for the OS to be a success with them. -- http://mail.python.org/mailman/listinfo/python-list -- Enviado desde mi dispositivo móvil Diego I. Hidalgo D. -- http://mail.python.org/mailman/listinfo/python-list
Re: using python ftp
Hi Matt,
I have a snippet to upload files (that match a particular search
pattern) to a remote server.
Variable names are self explanatory. You could tweak this a little to
download files instead.
from ftplib import FTP
ftp = FTP(hostname)
ftp.login(user_id,passwd)
ftp.cwd(remote_directory)
files_list=glob.glob(file_search_pattern)
for file in files_list:
try:
ftp.storlines('STOR ' + file, open(file))
except Exception, e:
print ('Failed to FTP file: %s' %(file))
ftp.close()
Regards,
Anurag
On Thu, Dec 23, 2010 at 5:33 AM, Matt Funk maf...@nmsu.edu wrote:
Hi,
i was wondering whether someone can point me whether the following
already exists.
I want to connect to a server , download various files (for whose name i
want to be able to use a wildcard), and store those files in a given
location on the hard drive. If the file already exists i do not want to
download it.
This seems fairly trivial and i would assume that there should be some
sort of implementation that does this easily but i didn't find anything
googling it.
Otherwise i was going to do it by hand using ftplib:
1) connect to server,
2) change to directory on server
3) get listing
4) match the file pattern i want to the listing
5) check if file already exists
6) download file if matched and doesn't exist
Can anyone offer any advice whether this already done somewhere?
thanks
matt
--
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--
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Re: Python Web App
Use editarea, that's the best option if you want something small, but as i said before i am developing a framework that allows you to create app's from the web and is much more complete than editarea. 2010/12/22, Sean secr...@gmail.com: I am wanting to learn python and I am test a Chrome OS notebook at the same time so I need something that will atleast tell me if I have any syntax errors. Although the more features the better that way learning is an easier experience. On Dec 22, 7:05 pm, Hidura hid...@gmail.com wrote: I am creating one, is on test, what kind of app do you want create? 2010/12/22, Sean secr...@gmail.com: Anybody know where I can find a Python Development Environment in the form of a web app for use with Chrome OS. I have been looking for a few days and all i have been able to find is some old discussions with python developers talking about they will want one for the OS to be a success with them. -- http://mail.python.org/mailman/listinfo/python-list -- Enviado desde mi dispositivo móvil Diego I. Hidalgo D. -- http://mail.python.org/mailman/listinfo/python-list -- Enviado desde mi dispositivo móvil Diego I. Hidalgo D. -- http://mail.python.org/mailman/listinfo/python-list
Re: Python Web App
My framework let you store online on a hosting server that the same framework provide. 2010/12/22, Hidura hid...@gmail.com: Use editarea, that's the best option if you want something small, but as i said before i am developing a framework that allows you to create app's from the web and is much more complete than editarea. 2010/12/22, Sean secr...@gmail.com: I am wanting to learn python and I am test a Chrome OS notebook at the same time so I need something that will atleast tell me if I have any syntax errors. Although the more features the better that way learning is an easier experience. On Dec 22, 7:05 pm, Hidura hid...@gmail.com wrote: I am creating one, is on test, what kind of app do you want create? 2010/12/22, Sean secr...@gmail.com: Anybody know where I can find a Python Development Environment in the form of a web app for use with Chrome OS. I have been looking for a few days and all i have been able to find is some old discussions with python developers talking about they will want one for the OS to be a success with them. -- http://mail.python.org/mailman/listinfo/python-list -- Enviado desde mi dispositivo móvil Diego I. Hidalgo D. -- http://mail.python.org/mailman/listinfo/python-list -- Enviado desde mi dispositivo móvil Diego I. Hidalgo D. -- Enviado desde mi dispositivo móvil Diego I. Hidalgo D. -- http://mail.python.org/mailman/listinfo/python-list
Re: using python ftp
On 23/12/2010 02:12, Anurag Chourasia wrote:
Hi Matt,
I have a snippet to upload files (that match a particular search
pattern) to a remote server.
Variable names are self explanatory. You could tweak this a little to
download files instead.
from ftplib import FTP
ftp = FTP(hostname)
ftp.login(user_id,passwd)
ftp.cwd(remote_directory)
files_list=glob.glob(file_search_pattern)
for file in files_list:
try:
ftp.storlines('STOR ' + file, open(file))
You should open the file in binary mode:
ftp.storlines('STOR ' + file, open(file, 'rb'))
This isn't necessary on *nix, but it's recommended for portability.
except Exception, e:
print ('Failed to FTP file: %s' %(file))
ftp.close()
[snip]
--
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Re: Python programming
5 in [2, 6, 5] True Sent from my iPhone On Dec 22, 2010, at 20:22, Maurice Shih rockitout...@yahoo.com wrote: Dear python-list@python.org, Thank you for taking the time to listen to my request. I'm a beginner programmer and I se python 2.6. I am making a program that needs a command that can check if a value is in a list. For example to check whether 5 is in [2, 6, 5,]. Thank you for hearing my request. Maurice Shih -- http://mail.python.org/mailman/listinfo/python-list -- http://mail.python.org/mailman/listinfo/python-list
Re: Python programming
Here you go. $ python Python 2.5.2 (r252:60911, Dec 2 2008, 09:26:14) [GCC 3.4.4 (cygming special, gdc 0.12, using dmd 0.125)] on cygwin Type help, copyright, credits or license for more information. A=[2,6,5] if 5 in A: ... print 'Yes' ... else: ... print 'No' ... Yes Regards, Anurag On Thu, Dec 23, 2010 at 6:52 AM, Maurice Shih rockitout...@yahoo.comwrote: Dear python-list@python.org, Thank you for taking the time to listen to my request. I'm a beginner programmer and I se python 2.6. I am making a program that needs a command that can check if a value is in a list. For example to check whether 5 is in [2, 6, 5,]. Thank you for hearing my request. Maurice Shih -- http://mail.python.org/mailman/listinfo/python-list -- http://mail.python.org/mailman/listinfo/python-list
Re: Python Web App
[Reordered to preserve context in bottom posting] On 2010-12-23, Hidura hid...@gmail.com wrote: 2010/12/22, Tim Harig user...@ilthio.net: On 2010-12-22, Sean secr...@gmail.com wrote: Anybody know where I can find a Python Development Environment in the form of a web app for use with Chrome OS. I have been looking for a few days and all i have been able to find is some old discussions with python developers talking about they will want one for the OS to be a success with them. Personally, I think a web app based IDE would be ghastly; but, you might have a look at Mozilla Skywriter (formerly Bespin): Why grashtly? I don't personally think the web makes a good framework for highly interactive applications as they must work within the constraints of the browser and IDEs are highly interactive applications by their very nature. Perhaps HTML5/CSS3 will change things; but, standard DOM manipulation, as I am accustomed to seeing it, cannot generate the kind of rendering that is available from native applications. Attempts to do so end up being kludgy. It also cannot handle the kinds of desktop integrations that are common for native applications without opening up serious security trust issues. (Can everybody say ActiveX fiasco?) Finally, there are difficulties in handling keystrokes without conflicting with the browser's native key bindings. I seldom ever touch a mouse and I am a huge fan of vi, mutt, slrn, screen, ratpoison, etc. where the primary interface is totally accessable through the keyboard without having to tab through many options. -- http://mail.python.org/mailman/listinfo/python-list
Re: Generator question
Dan Stromberg drsali...@gmail.com wrote: You likely want a class variable: Sounds like an elegant solution. Thanks! Victor. -- Victor Eijkhout -- eijkhout at tacc utexas edu -- http://mail.python.org/mailman/listinfo/python-list
Re: Python Web App
Ok, but you are comparing a web-based framework with a native-based framework that use the components of the system to make all the things that need, a web-based framewok use the resourses of the browser to make it all, so the developer that use a framework on the web can't expect get the same results, in my case i beleive that a web-based framework adjust better to the needs if you'll make a web-app, otherwise use eclipse or netbeans. 2010/12/22, Tim Harig user...@ilthio.net: [Reordered to preserve context in bottom posting] On 2010-12-23, Hidura hid...@gmail.com wrote: 2010/12/22, Tim Harig user...@ilthio.net: On 2010-12-22, Sean secr...@gmail.com wrote: Anybody know where I can find a Python Development Environment in the form of a web app for use with Chrome OS. I have been looking for a few days and all i have been able to find is some old discussions with python developers talking about they will want one for the OS to be a success with them. Personally, I think a web app based IDE would be ghastly; but, you might have a look at Mozilla Skywriter (formerly Bespin): Why grashtly? I don't personally think the web makes a good framework for highly interactive applications as they must work within the constraints of the browser and IDEs are highly interactive applications by their very nature. Perhaps HTML5/CSS3 will change things; but, standard DOM manipulation, as I am accustomed to seeing it, cannot generate the kind of rendering that is available from native applications. Attempts to do so end up being kludgy. It also cannot handle the kinds of desktop integrations that are common for native applications without opening up serious security trust issues. (Can everybody say ActiveX fiasco?) Finally, there are difficulties in handling keystrokes without conflicting with the browser's native key bindings. I seldom ever touch a mouse and I am a huge fan of vi, mutt, slrn, screen, ratpoison, etc. where the primary interface is totally accessable through the keyboard without having to tab through many options. -- http://mail.python.org/mailman/listinfo/python-list -- Enviado desde mi dispositivo móvil Diego I. Hidalgo D. -- http://mail.python.org/mailman/listinfo/python-list
Re: How to pop the interpreter's stack?
On Wed, 22 Dec 2010 13:53:20 -0800, Carl Banks wrote:
On Dec 22, 8:52 am, kj no.em...@please.post wrote:
In mailman.65.1292517591.6505.python-l...@python.org Robert Kern
robert.k...@gmail.com writes:
Obfuscating the location that an exception gets raised prevents a lot
of debugging...
The Python interpreter does a lot of that obfuscation already, and I
find the resulting tracebacks more useful for it.
An error message is only useful to a given audience if that audience
can use the information in the message to modify what they are doing to
avoid the error.
So when the audience files a bug report it's not useful for them to
include the whole traceback?
Well, given the type of error KJ has been discussing, no, it isn't useful.
Fault: function raises documented exception when passed input that
is documented as being invalid
What steps will reproduce the problem?
1. call the function with invalid input
2. read the exception that is raised
3. note that it is the same exception as documented
What is the expected output? What do you see instead?
Excepted somebody to hit me on the back of the head and tell me
not to call the function with invalid input. Instead I just got
an exception.
You seem to have completely missed that there will be no bug report,
because this isn't a bug. (Or if it is a bug, the bug is elsewhere,
external to the function that raises the exception.) It is part of the
promised API. The fact that the exception is generated deep down some
chain of function calls is irrelevant.
The analogy is this: imagine a function that delegates processing of the
return result to different subroutines:
def func(arg):
if arg 0:
return _inner1(arg)
else:
return _inner2(arg)
This is entirely irrelevant to the caller. When they receive the return
result from calling func(), they have no way of knowing where the result
came from, and wouldn't care even if they could. Return results hide
information about where the result was calculated, as they should. Why
shouldn't deliberate, explicit, documented exceptions be treated the same?
Tracebacks expose the implementation details of where the exception was
generated. This is the right behaviour if the exception is unexpected --
a bug internal to func -- since you need knowledge of the implementation
of func in order to fix the unexpected exception. So far so good -- we
accept that Python's behaviour under these circumstances is correct.
But this is not the right behaviour when the exception is expected, e.g.
an explicitly raised exception in response to an invalid argument. In
this case, the traceback exposes internal details of no possible use to
the caller. What does the caller care if func() delegates (e.g.) input
checking to a subroutine? The subroutine is an irrelevant implementation
detail. The exception is promised output of the function, just as much so
as if it were a return value.
Consider the principle that exceptions should be dealt with as close as
possible to the actual source of the problem:
f('good input')
Traceback (most recent call last):
File stdin, line 1, in module
File stdin, line 2, in f
File stdin, line 2, in g
File stdin, line 2, in h
File stdin, line 2, in i
File stdin, line 2, in j
File stdin, line 2, in k=== error occurs here, and shown here
ValueError
But now consider the scenario where the error is not internal to f, but
external. The deeper down the stack trace you go, the further away from
the source of the error you get. The stack trace now obscures the source
of the error, rather than illuminating it:
f('bad input')=== error occurs here
Traceback (most recent call last):
File stdin, line 1, in module
File stdin, line 2, in f
File stdin, line 2, in g
File stdin, line 2, in h
File stdin, line 2, in i
File stdin, line 2, in j
File stdin, line 2, in k=== far from the source of error
ValueError
There's no point in inspecting function k for a bug when the problem has
nothing to do with k. The problem is that the input fails to match the
pre-conditions for f. From the perspective of the caller, the error has
nothing to do with k, k is a meaningless implementation detail, and the
source of the error is the mismatch between the input and what f expects.
And so by the principle of dealing with exceptions as close as possible
to the source of the error, we should desire this traceback instead:
f('bad input')=== error occurs here
Traceback (most recent call last):
File stdin, line 1, in module
File stdin, line 2, in f=== matches where the error occurs
ValueError
In the absence of any practical way for function f to know whether an
arbitrary exception in a subroutine is a bug or not, the least-worst
decision is Python's current behaviour: take the conservative, risk-
adverse path and assume the worst, treat the exception as a bug in the
subroutine, and
Re: issubclass(dict, Mapping)
On Thu, 23 Dec 2010 01:41:08 +, kj wrote: In 4d127d5e$0$29997$c3e8da3$54964...@news.astraweb.com Steven D'Aprano steve+comp.lang.pyt...@pearwood.info writes: On Wed, 22 Dec 2010 14:20:51 +, kj wrote: Here's another example, fresh from today's crop of wonders: (v. 2.7.0) from collections import Mapping issubclass(dict, Mapping) True dict.__bases__ (type 'object',) [issubclass(b, Mapping) for b in dict.__bases__] [False] So dict is a subclass of Mapping, even though none of the bases of dict is either Mapping or a subclass of Mapping. Great. Yes. So what? That's being deliberately obtuse. The situation described goes smack against standard OOP semantics, What are these standard OOP semantics you're referring to, and who made them standard? If people can't even decide whether multiple inheritance should be allowed or not, what makes you think that there is any such thing as standard OOP? I think you are confusing concrete implementation details with the interface. The interface for subclass testing in Python is as follows: A class K is a subclass of class C if, and only if, issubclass(C, K) returns a true result. That's it. Everything else is implementation. __bases__ is implementation. __subclasscheck__ is implementation. If Python adds a third mechanism for implementing subclass checks in version 3.3 or 3.4, the interface will just continue to work correctly. which would be fine if all this stuff was documented clearly and reasonably, i.e. in one (preferably official) place rather than scattered over a bazillion separate documents, PEP this, module that, GvR musing #42, etc. This is documented, in the docs. http://docs.python.org/reference/datamodel.html#customizing-instance-and-subclass-checks Nobody says the Python docs are perfect, but most things you ask are in there. Patches for the docs to improve them are welcome. -- Steven -- http://mail.python.org/mailman/listinfo/python-list
Re: general problem when subclassing a built-in class
On 2010-12-22 20:22:36 -0500, kj said: Suppose that you want to implement a subclass of built-in class, to meet some specific design requirements. Where in the Python documentation can one find the information required to determine the minimal[1] set of methods that one would need to override to achieve this goal? (Rest elided.) The short answer is that you can't everything you want. If some behaviour or implementation detail isn't documented, you can't make any assumptions about how a class works, even if you really want to. Whatever you figure out by educated guesswork (or, even better, reading the source) is, absent documentation, not guaranteed, and behaviour that's not guaranteed can and will change whenever the code's maintaners feel like it. This is true for for builtins, for things in the standard library, and for things in competently-maintained third party libraries. Requiring that every class document its internals extensively enough to permit subclasses to modify behaviour in totally arbitrary ways has to be balanced against allowing each class's interface to usefully abstract its internal workings. Especially in a duck-typed language like Python, there's very little need for subclassing simply to intercept one or two method calls, and the resulting composition-based system is both more flexible and, being based on documented and stable interfaces, easier to maintain and support. Subclassing is a powerful tool, not suited to every design problem. In your case (tracking timestamps in a dict-like container), you're probably better off implementing your own dict-like container, with support for as much or as little of the protocol you want. You can do that without subclassing dict: the protocol for dict is not difficult to implement, especially if your backing storage is a real dict. What forces do you imagine require you to use a subclass for this? -o -- http://mail.python.org/mailman/listinfo/python-list
Re: Python Web App
On 2010-12-23, Hidura hid...@gmail.com wrote: Ok, but you are comparing a web-based framework with a native-based framework that use the components of the system to make all the things that need, a web-based framewok use the resourses of the browser to Right. That is exactly what I am comparing. make it all, so the developer that use a framework on the web can't expect get the same results, in my case i beleive that a web-based Which is exactly the problem with web apps that are highly interactive. My suggestion, is not to develope a web based IDE or use one. It just isn't something that the web was designed to do well. expect get the same results, in my case i beleive that a web-based framework adjust better to the needs if you'll make a web-app, Most IDEs that are targeted at web developement have a built in web browser or strong integration with one to run the web app as you are developing it. I don't see any advantage or the necessity of actually running the IDE code itself in the browser. otherwise use eclipse or netbeans. I would; but then, I wouldn't purchase an operating system that is entirely based on a web browser. -- http://mail.python.org/mailman/listinfo/python-list
Re: Re: Python Web App
Which is exactly the problem with web apps that are highly interactive. My suggestion, is not to develope a web based IDE or use one. It just isn't something that the web was designed to do well. Is not a problem of the IDE, the problem is on what the developer expect as i said i you want something to the desktop well use an IDE that creates apps for desktop, but if you need something for the web you can try on a web-based IDE. Most IDEs that are targeted at web developement have a built in web browser or strong integration with one to run the web app as you are developing it. I don't see any advantage or the necessity of actually running the IDE code itself in the browser. That's the problem an integration with one, my IDE works on all of them and the result is the same in IE and Chrome or FF, a web page cannot be designed to one browser it has to be designed to all the browser and have to be same. On the visualization is more difficult but nobody could control perfectly that but on the results of the data is has to be the same. I would; but then, I wouldn't purchase an operating system that is entirely based on a web browser. I support that, but the target of those OS are use the share resources of the pc, smartphone, etc and the server. On Dec 22, 2010 11:54pm, Tim Harig user...@ilthio.net wrote: On 2010-12-23, Hidura hid...@gmail.com wrote: Ok, but you are comparing a web-based framework with a native-based framework that use the components of the system to make all the things that need, a web-based framewok use the resourses of the browser to Right. That is exactly what I am comparing. make it all, so the developer that use a framework on the web can't expect get the same results, in my case i beleive that a web-based Which is exactly the problem with web apps that are highly interactive. My suggestion, is not to develope a web based IDE or use one. It just isn't something that the web was designed to do well. expect get the same results, in my case i beleive that a web-based framework adjust better to the needs if you'll make a web-app, Most IDEs that are targeted at web developement have a built in web browser or strong integration with one to run the web app as you are developing it. I don't see any advantage or the necessity of actually running the IDE code itself in the browser. otherwise use eclipse or netbeans. I would; but then, I wouldn't purchase an operating system that is entirely based on a web browser. -- http://mail.python.org/mailman/listinfo/python-list -- http://mail.python.org/mailman/listinfo/python-list
Re: Python programming
If it's a big list and you're checking multiple times, you're probably better off converting the list to a set, and using in on the set. Once you have your list converted to a set, you can update both quickly. On Wed, Dec 22, 2010 at 5:22 PM, Maurice Shih rockitout...@yahoo.comwrote: Dear python-list@python.org, Thank you for taking the time to listen to my request. I'm a beginner programmer and I se python 2.6. I am making a program that needs a command that can check if a value is in a list. For example to check whether 5 is in [2, 6, 5,]. Thank you for hearing my request. Maurice Shih -- http://mail.python.org/mailman/listinfo/python-list -- http://mail.python.org/mailman/listinfo/python-list
Re: simple games w/o pygame
On Dec 22, 11:40 am, William Gill nore...@domain.invalid wrote: I am teaching an 11 year old who wants to learn programming. I chose Python, and it is working well. I seem to remember lots of simple script games, like quizzes, number games etc. that would be good for his tutorial. However, now all I can find is more complex games using Pygame. Can anyone help me out here? Maybe you can check out the book Python Programming for the Absolute Beginner, 3rd Edition by Michael Dawson. Its emphasis is on simple games. My son is (who is older - just turned 17) is working through it now and finding it easy going. -- http://mail.python.org/mailman/listinfo/python-list
Re: compiling Python 2.7.1 with readline module fails on Debian (Virtualbox)
On 22/12/2010 18:57, Jim Pharis wrote: are you running make clean for good measure? Yes, i am. I am gong to try and uninstall Python2.7 from $HOME/local and see if that makes a difference. Maybe it interferes with the build process? Regards, Benedict -- http://mail.python.org/mailman/listinfo/python-list
[issue9017] doctest option flag to enable/disable some chunk of doctests?
Changes by Éric Araujo mer...@netwok.org: -- nosy: +eric.araujo stage: unit test needed - needs patch versions: +Python 3.3 -Python 3.2 ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue9017 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue10755] Add posix.fdlistdir
Martin v. Löwis mar...@v.loewis.de added the comment: What's the use case for this function? -- ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue10755 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue9085] Version number inconsistency in email package
Éric Araujo mer...@netwok.org added the comment: If there is no further discussion, I’d say the original bug is fixed anc this report should be closed. -- nosy: +eric.araujo ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue9085 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue8847] crash appending list and namedtuple
Changes by Éric Araujo mer...@netwok.org: -- nosy: +eric.araujo ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue8847 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue10755] Add posix.fdlistdir
Ross Lagerwall rosslagerw...@gmail.com added the comment: When maintaining an fd to implement a per thread current directory, you can use it to get a list of files in the directory. For security reasons, instead of a named path, you can keep an fd to a directory so that if the path is changed externally while performing an operation, the open fd still points to the original directory. This function then allows you to list the contents of that fd. I think this is needed for #4489. -- ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue10755 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue8885] markupbase declaration errors aren't recoverable
Changes by Éric Araujo mer...@netwok.org: -- nosy: +eric.araujo resolution: invalid - stage: - needs patch title: markerbase declaration errors aren't recoverable - markupbase declaration errors aren't recoverable versions: +Python 2.7 -Python 2.6 ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue8885 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue8964] platform._sys_version does not parse correctly IronPython 2.x version
Éric Araujo mer...@netwok.org added the comment: Do you want to work on a patch? -- nosy: +eric.araujo stage: - needs patch title: Method _sys_version() module Lib\platform.py does not parse correctly IronPython 2.x version - platform._sys_version does not parse correctly IronPython 2.x version versions: +Python 2.7, Python 3.1, Python 3.2 -Python 2.6 ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue8964 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue9074] subprocess closes standard file descriptors when it should not
Changes by Éric Araujo mer...@netwok.org: -- keywords: +needs review nosy: +astrand stage: - patch review title: [includes patch] subprocess module closes standard file descriptors when it should not - subprocess closes standard file descriptors when it should not versions: +Python 2.7, Python 3.1, Python 3.2 -Python 2.6 ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue9074 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue4489] shutil.rmtree is vulnerable to a symlink attack
Changes by Éric Araujo mer...@netwok.org: -- nosy: +eric.araujo stage: - needs patch versions: +Python 2.5 ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue4489 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue9399] Provide a 'print' action for argparse
Éric Araujo mer...@netwok.org added the comment: Thinking again about that, what’s wrong with argparse replacing \n with spaces and doing its own line wrapping? -- versions: +Python 3.3 -Python 3.2 ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue9399 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue8754] ImportError: quote bad module name in message
Georg Brandl ge...@python.org added the comment: I suppose it's not a good test, since your non-ascii name presumably was encoded in UTF-8, which is the encoding that PyUnicode_FromString uses. -- ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue8754 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue4761] create Python wrappers for openat() and others
Georg Brandl ge...@python.org added the comment: Reference counting is not always correct. For example, in unlinkat if (res 0) return posix_error(); Py_DECREF(opath); (return None) the DECREF should be before the error check. (Note that you can use the Py_RETURN_NONE macro to save INCREF'ing Py_None explicitly.) Sometimes you use posix_error, sometimes posix_error_with_allocated_filename; is that deliberate? Also, the documentation for each function should get .. versionadded:: 3.3 tags. Otherwise, this looks good and ready for inclusion when py3k is open for new features again. -- nosy: +georg.brandl ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue4761 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue4761] create Python wrappers for openat() and others
Ross Lagerwall rosslagerw...@gmail.com added the comment: New patch *should* have fixed up reference counting and version tags. I standardized all the error calls to posix_error. -- Added file: http://bugs.python.org/file20137/i4761_v4.patch ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue4761 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue10757] zipfile.write, arcname should be bytestring
New submission from Jacek Jabłoński conexion2...@gmail.com:
file = 'somefile.dat'
filename = ółśąśółąś.dat
zip = zipfile.ZipFile('archive.zip', 'w', zipfile.ZIP_DEFLATED)
zip.write(file, filename)
above produces very nasty filename in zip archive.
*
file = 'somefile.dat'
filename = ółśąśółąś.dat
zip = zipfile.ZipFile('archive.zip', 'w', zipfile.ZIP_DEFLATED)
zip.write(file, filename.encode('cp852'))
this produces TypeError: expected an object with the buffer interface
Documentation says that:
There is no official file name encoding for ZIP files. If you have unicode file
names, you must convert them to byte strings in your desired encoding before
passing them to write().
I convert them to byte string but it ends with an error.
If it is documentation bug, what is the proper way to have filenames like
ółśąśółąś in zip archive?
--
components: Library (Lib)
messages: 124499
nosy: connexion2000
priority: normal
severity: normal
status: open
title: zipfile.write, arcname should be bytestring
type: compile error
versions: Python 3.1
___
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http://bugs.python.org/issue10757
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[issue10758] posix_access swallows all errors
New submission from Georg Brandl ge...@python.org: access(2) can return errnos that correspond to input errors or general system faults, such as EINVAL, EIO or ENOMEM. In this case, an exception should be raised instead of returning False. It is probably best to whitelist those errnos that indicate missing access -- it needs to be discussed whether that is just EACCES, or also e.g. ENOENT. -- components: Library (Lib) messages: 124500 nosy: georg.brandl priority: normal severity: normal stage: needs patch status: open title: posix_access swallows all errors type: behavior versions: Python 2.7, Python 3.1, Python 3.2 ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue10758 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue4761] create Python wrappers for openat() and others
Georg Brandl ge...@python.org added the comment: Thanks for the update! Three more comments: * the new constants doc should also get a versionadded * faccessat should check for EBADF, EINVAL and ENOTDIR and raise an error if they are returned, since these are input errors Or, alternately, a range of errnos should be whitelisted for both access and faccessat. However, this problem should be handled in a separate issue, I've opened #10758 for that. * The octal modes in docstrings and docs should be specified in Python 3 octal syntax, e.g. 0o777. -- ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue4761 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue9990] PyMemoryView_FromObject alters the Py_buffer after calling PyObject_GetBuffer when ndim 1
Mark Dickinson dicki...@gmail.com added the comment: Antoine, a couple of questions: (1) Is there documentation for the 'smalltable' field of the Py_buffer struct anywhere? What are the requirements for the exporter here? E.g., is it / should it be a requirement that shape, strides and suboffsets are all NULL whenever 'smalltable' is used? (2) Same question for the 'obj' field: what's the purpose of this field, from the POV of 3rd party buffer exporters? -- ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue9990 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
