Re: subprocess.Popen does not close pipe in an error case
On Wed, 06 Jan 2010 19:05:40 -0800, Steven K. Wong wrote: > Well, the example code at > http://www.python.org/ ... /subprocess.html#replacing-shell-pipeline > has the same issue: > Perhaps the doc can be improved to remind folks to close p1.stdout if > the calling process doesn't need it, unless wait() is changed to close > it and p1.wait() is called. > > Am I making any sense here? The docs should include the p1.stdout.close(). It isn't needed in the typical case, where p2 runs until EOF on stdin, but (as you have noticed) it matters if p2 terminates prematurely. -- http://mail.python.org/mailman/listinfo/python-list
Re: Ask how to use HTMLParser
On Fri, 08 Jan 2010 11:44:48 +0800, Water Lin wrote: > I am a new guy to use Python, but I want to parse a html page now. I > tried to use HTMLParse. Here is my sample code: > -- > from HTMLParser import HTMLParser Note that HTMLParser only tokenises HTML; it doesn't actually *parse* it. You just get a stream of tag, text, entity, text, tag, ..., not a parse tree. In particular, if an element has its start and/or end tags omitted, you won't get any notification about the start and/or end of the element; you have to figure that out yourself from the fact that you're getting a tag which wouldn't be allowed outside or inside the element. E.g. if the document has omitted tags, if you get a tag when you are (or *thought* that you were) already within a paragraph, you can infer the omitted tag. If you want an actual parser, look at BeautifulSoup. This also does a good job of handling invalid HTML (which seems to be far more common than genuine HTML). -- http://mail.python.org/mailman/listinfo/python-list
Re: lightweight encryption of text file
On Fri, 08 Jan 2010 20:14:51 +0100, Daniel Fetchinson wrote: > I have a plain text file which I would like to protect in a very > simple minded, yet for my purposes sufficient, way. I'd like to > encrypt/convert it into a binary file in such a way that possession of > a password allows anyone to convert it back into the original text > file while not possessing the password one would only see the > following with the standard linux utility 'file': > What would be the simplest way to achieve this using preferably stock > python without 3rd party modules? If a not too complex 3rd party > module made it really simple that would be acceptable too. RC4 (aka ArcFour) is quite trivial to implement, and better than inventing your own cipher or using a Vignere: import itertools class arcfour: def __init__(self, key): self.s = range(256) self.schedule(map(ord, key)) self.pad = self.prng() def swap(self, i, j): self.s[i], self.s[j] = self.s[j], self.s[i] def schedule(self, key): j = 0 for i, c in zip(xrange(256), itertools.cycle(key)): j = (j + self.s[i] + c) % 256 self.swap(i, j) def prng(self): i = j = 0 while True: i = (i + 1) % 256 j = (j + self.s[i]) % 256 self.swap(i, j) yield self.s[(self.s[i] + self.s[j]) % 256] def crypt(self, string): chars = (chr(c ^ r) for c, r in zip(map(ord, string), self.pad)) return ''.join(chars) I suggest that you don't use the password itself as the key, unless you're sure that a low-entropy string won't be used. Instead, create an SHA hash (see the sha and hashlib modules) of the password and use that. -- http://mail.python.org/mailman/listinfo/python-list
Re: lightweight encryption of text file
>> I have a plain text file which I would like to protect in a very >> simple minded, yet for my purposes sufficient, way. I'd like to >> encrypt/convert it into a binary file in such a way that possession of >> a password allows anyone to convert it back into the original text >> file while not possessing the password one would only see the >> following with the standard linux utility 'file': > >> What would be the simplest way to achieve this using preferably stock >> python without 3rd party modules? If a not too complex 3rd party >> module made it really simple that would be acceptable too. > > RC4 (aka ArcFour) is quite trivial to implement, and better than inventing > your own cipher or using a Vignere: > > import itertools > > class arcfour: > def __init__(self, key): > self.s = range(256) > self.schedule(map(ord, key)) > self.pad = self.prng() > > def swap(self, i, j): > self.s[i], self.s[j] = self.s[j], self.s[i] > > def schedule(self, key): > j = 0 > for i, c in zip(xrange(256), itertools.cycle(key)): > j = (j + self.s[i] + c) % 256 > self.swap(i, j) > > def prng(self): > i = j = 0 > while True: > i = (i + 1) % 256 > j = (j + self.s[i]) % 256 > self.swap(i, j) > yield self.s[(self.s[i] + self.s[j]) % 256] > > def crypt(self, string): > chars = (chr(c ^ r) for c, r in zip(map(ord, string), self.pad)) > return ''.join(chars) > > I suggest that you don't use the password itself as the key, unless you're > sure that a low-entropy string won't be used. Instead, create an SHA hash > (see the sha and hashlib modules) of the password and use that. Thanks, this looks very simple too, but where is the decryption code? Wikipedia seems to suggest that encryption and decryption are both the same but running crypt on the output of crypt doesn't give back the original string. So probably I'm misunderstanding something. Cheers, Daniel -- Psss, psss, put it down! - http://www.cafepress.com/putitdown -- http://mail.python.org/mailman/listinfo/python-list
Computer Music Toolkit (CMT) ?
Greetings. Is there a way to get at the Computer Music Toolkit (CMT) http://www.ladspa.org/cmt/ functionality from Python (Python3 in my case) ? Googling is confusing because of www.cmt.com and cmt-graph and openscientist.lal.in2p3.fr/v9/cmt.html and pyAMISecure_and_cmt and so on... Regards, Peter -- Peter Billam www.pjb.com.auwww.pjb.com.au/comp/contact.html -- http://mail.python.org/mailman/listinfo/python-list
Re: Direct use of bytearray buffers with ctypes ?
Oki, it seems I've found. To directly use a bytearray buffer from ctypes, you must first create a compatible ctypes type (I.E, a char array of same size), and only then instanciate this new type with newtype.from_buffer (bytearray_object). The little danger is : you must NOT change the size of bytearray as long as the ctypes array targets its inner buffer, else of cousre memory reallocations occurs, and your ctypes array points to invalid memory (awaiting a pretty segfault). But modifying chars or characters ranges from the buffer, as well via the bytearray object than via the ctypes array, is fine. I don't think problems can occur if both sides are accessed simultaneously, even though ctypes operations may release the GIL while they execute... the only race condition is the access of a memory segment, isn't it ? No crash shall occur with this... IDLE 2.6.4 >>> import ctypes >>> a = bytearray(3) >>> mytype = ctypes.c_char * 3 >>> h = mytype.from_buffer(a) >>> h <__main__.c_char_Array_3 object at 0x02B06350> >>> h[:] = "abc" >>> a bytearray(b'abc') >>> h[0] = "k" >>> a bytearray(b'kbc') -- http://mail.python.org/mailman/listinfo/python-list
Re: Prepend to logging message
On 10 ene, 03:27, Ishwor Gurung wrote:
> Joan,
>
> 2010/1/10 Joan Miller :
>
>
>
> > How to prepend anything to a logging message? Is possible to do it
> > from the dictionary object (ExtraLog) or is there is that override
> > process() [1]?
>
> > --
> > class ExtraLog(object):
>
> > def __getitem__(self, name):
> > if name == 'foo':
> > result = 'testing'
> > return result
>
> > def __iter__(self):
> > keys = ['foo',]
> > keys.extend(self.__dict__.keys())
> > return iter(keys)
>
> > logger = logging.LoggerAdapter(logging.getLogger('foo'), ExtraLog())
> > --
>
> Yep. Just subclass LoggerAdapter and override process(..)
> Read
> this:http://docs.python.org/library/logging.html#adding-contextual-informa...
> --
> Regards
> Ishwor Gurung
> Key id:0xa98db35e
> Key fingerprint:FBEF 0D69 6DE1 C72B A5A8 35FE 5A9B F3BB 4E5E 17B5
Any example to override process() ?
--
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Re: Computer Music Toolkit (CMT) ?
Peter Billam, 10.01.2010 10:15: Greetings. Is there a way to get at the Computer Music Toolkit (CMT) http://www.ladspa.org/cmt/ functionality from Python (Python3 in my case) ? Googling is confusing because of www.cmt.com and cmt-graph and openscientist.lal.in2p3.fr/v9/cmt.html and pyAMISecure_and_cmt and so on... Just a note on the last paragraph: searching for acronyms is usually simplified by adding the spelled-out name to the search keywords. It's highly unlikely that someone would write a Python tool for a library or application without putting the complete name of the thing it's made for on the project homepage. Stefan -- http://mail.python.org/mailman/listinfo/python-list
Re: Porblem with xlutils/xlrd/xlwt
On Jan 9, 8:23 am, John Machin wrote:
> On Jan 9, 9:56 pm, pp wrote:
>
> > On Jan 9, 3:52 am, Jon Clements wrote:
>
> > > On Jan 9, 10:44 am, pp wrote:
>
> > > > On Jan 9, 3:42 am, Jon Clements wrote:
>
> > > > > On Jan 9, 10:24 am, pp wrote:
> > > > yeah all my versions are latest fromhttp://www.python-excel.org.
> > > > just checked!!
>
> How did you check?
>
> > > > what could be the problem?
>
> > > Does rb = xlrd.open_workbook('somesheet.xls', on_demand=True) work by
> > > itself?
>
> > Yes it does. The problem is with line: wb = copy(rb)
> > here I am getting the error: AttributeError: 'Book' object has no
> > attribute 'on_demand'
>
> Please replace the first 4 lines of your script by these 6 lines:
>
> import xlrd
> assert xlrd.__VERSION__ == "0.7.1"
> from xlwt import easyxf
> from xlutils.copy import copy
> rb = xlrd.open_workbook(
> 'source.xls',formatting_info=True, on_demand=False)
>
> and run it again. Please copy all the output and paste it into your
> response.
This time when I ran the code sent by you I got the following
results:I am using ipython for running the code.
AssertionErrorTraceback (most recent call
last)
/home/parul/CODES/copy_1.py in ()
1
> 2 import xlrd
3 assert xlrd.__VERSION__ == "0.7.1"
4 from xlwt import easyxf
5 from xlutils.copy import copy
6 rb = xlrd.open_workbook('source.xls',formatting_info=True,
on_demand=False)
AssertionError:
WARNING: Failure executing file:
I used www.python-excel.org to get xlrd and xlwt .. so they are latest
versions.
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Re: Prepend to logging message
Joan Miller wrote:
> How to prepend anything to a logging message? Is possible to do it
> from the dictionary object (ExtraLog) or is there is that override
> process() [1]?
>
> --
> class ExtraLog(object):
>
> def __getitem__(self, name):
> if name == 'foo':
> result = 'testing'
> return result
>
> def __iter__(self):
> keys = ['foo',]
> keys.extend(self.__dict__.keys())
> return iter(keys)
format = "foo=%(foo)s " + logging.BASIC_FORMAT
logging.basicConfig(format=format)
logger = logging.LoggerAdapter(logging.getLogger('foo'), ExtraLog())
logger.error("yadda")
Is that what you want?
Peter
--
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(non-python) upgrading a MySQL database
>> ... And I am interested in cleaning this up. I should probably >> start with the matter of databases, since that's something I won't be able >> to easily change once clients actually start entering data. Please share >> with me any further concepts or questions to get me thinking how to redesign >> the databases. I maintain my (MySQL) databases in an agile fashion. That means I start small, and let my databases evolve along with my applications. So the schema changes a lot during development. I take into account that the databases already contain data and that it must be preserved and migrated. I wrote a howto on my upgrading method and it can be found here: http://www.howtoforge.org/node/4833 Hope this is of any help. Good luck, Dikkie -- http://mail.python.org/mailman/listinfo/python-list
Re: Porblem with xlutils/xlrd/xlwt
On Jan 10, 8:51 pm, pp wrote:
> On Jan 9, 8:23 am, John Machin wrote:
>
>
>
> > On Jan 9, 9:56 pm, pp wrote:
>
> > > On Jan 9, 3:52 am, Jon Clements wrote:
>
> > > > On Jan 9, 10:44 am, pp wrote:
>
> > > > > On Jan 9, 3:42 am, Jon Clements wrote:
>
> > > > > > On Jan 9, 10:24 am, pp wrote:
> > > > > yeah all my versions are latest fromhttp://www.python-excel.org.
> > > > > just checked!!
>
> > How did you check?
You didn't answer this question.
>
> > > > > what could be the problem?
>
> > > > Does rb = xlrd.open_workbook('somesheet.xls', on_demand=True) work by
> > > > itself?
>
> > > Yes it does. The problem is with line: wb = copy(rb)
> > > here I am getting the error: AttributeError: 'Book' object has no
> > > attribute 'on_demand'
>
> > Please replace the first 4 lines of your script by these 6 lines:
>
> > import xlrd
> > assert xlrd.__VERSION__ == "0.7.1"
> > from xlwt import easyxf
> > from xlutils.copy import copy
> > rb = xlrd.open_workbook(
> > 'source.xls',formatting_info=True, on_demand=False)
>
> > and run it again. Please copy all the output and paste it into your
> > response.
>
> This time when I ran the code sent by you I got the following
> results:I am using ipython for running the code.
>
> AssertionError Traceback (most recent call
> last)
>
> /home/parul/CODES/copy_1.py in ()
> 1
> > 2 import xlrd
> 3 assert xlrd.__VERSION__ == "0.7.1"
> 4 from xlwt import easyxf
> 5 from xlutils.copy import copy
> 6 rb = xlrd.open_workbook('source.xls',formatting_info=True,
> on_demand=False)
>
> AssertionError:
> WARNING: Failure executing file:
>
Your traceback appears to show an AssertionError from an import
statement. We could do without an extra layer of noise in the channel;
please consider giving ipython the flick (for debug purposes, at
least) and use Python to run your script from the shell prompt.
Change the second line to read:
print xlrd.__VERSION__
> I used www.python-excel.org to get xlrd and xlwt .. so they are latest
> versions.
Let's concentrate on xlrd. I presume that means that you clicked
on the xlrd Download link which took you to http://pypi.python.org/pypi/xlrd
from which you can download the latest version of the package. That
page has "xlrd 0.7.1" in a relatively large font at the top. You would
have been presented with options to download one of these
xlrd-0.7.1.tar.gz
xlrd-0.7.1.win32.exe
xlrd-0.7.1.zip
(each uploaded on 2009-06-01).
Which one did you download, and then what did you do with it?
Or perhaps you ignored those and read further down to "Download link"
which took you to an out-of-date page but you didn't notice the
"0.6.1" in large bold type at the top nor the "Page last updated on 11
June 2007" at the bottom nor the "0.6.1" in the name of the file that
you downloaded ... sorry about that; I've smacked the webmaster about
the chops :-)
Cheers,
John
--
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Re: Prepend to logging message
On 10 ene, 10:26, Peter Otten <__pete...@web.de> wrote:
> Joan Miller wrote:
> > How to prepend anything to a logging message? Is possible to do it
> > from the dictionary object (ExtraLog) or is there is that override
> > process() [1]?
>
> > --
> > class ExtraLog(object):
>
> > def __getitem__(self, name):
> > if name == 'foo':
> > result = 'testing'
> > return result
>
> > def __iter__(self):
> > keys = ['foo',]
> > keys.extend(self.__dict__.keys())
> > return iter(keys)
>
> format = "foo=%(foo)s " + logging.BASIC_FORMAT
> logging.basicConfig(format=format)
> logger = logging.LoggerAdapter(logging.getLogger('foo'), ExtraLog())
> logger.error("yadda")
>
> Is that what you want?
>
> Peter
I want that a message can be modified before of being logged. i.e. for
"yadda" I would that were preppend 2 spaces. (And I want not manage
that in the format to manage the indentation of all text)
--
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getopt not raising exception
Hello, I'm having problems getting getopt to function correctly. Basically, no exception is being raised if no argument is passed to the code snippet below. I've read the Python documentation and tried example code from various sources which should cause an exception, only they don't. I've also tried executing the code on different machines too but to no avail. I'm sure I'm obviously doing something wrong but can't determine what. Any help would be much appreciated indeed. import sys, getopt try: opts, args = getopt.getopt(sys.argv, "h:", ["help"]) except getopt.GetoptError: print "error" sys.exit(2) If no args are passed when the script is run there is no exception raised. Why? Surely the "h:" means that this option must be passed? Thanks, -- Matt -- http://mail.python.org/mailman/listinfo/python-list
Re: getopt not raising exception
Matthew Lear wrote: > Hello, > > I'm having problems getting getopt to function correctly. Basically, no > exception is being raised if no argument is passed to the code snippet > below. I've read the Python documentation and tried example code from > various sources which should cause an exception, only they don't. I've > also tried executing the code on different machines too but to no avail. > I'm sure I'm obviously doing something wrong but can't determine what. > Any help would be much appreciated indeed. > > import sys, getopt > > try: > opts, args = getopt.getopt(sys.argv, "h:", ["help"]) > except getopt.GetoptError: > print "error" > sys.exit(2) > > If no args are passed when the script is run there is no exception > raised. Why? Surely the "h:" means that this option must be passed? > > Thanks, > -- Matt That's not what ":" means. It means that, *if* the option is passed, it must be followed by an additional argument, e.g.: foo.py -h something If you require that -h be passed, it's not much of an option! You should use a regular argument and check len(args) or somesuch. Or, if you must keep it an "option", do something equivalent for that. BTW: Checked out optparse? It's bigger and sexier! -- Matt Nordhoff -- http://mail.python.org/mailman/listinfo/python-list
integer and string compare, is that correct?
Hi, being a causal python user (who likes the language quite a lot) it took me a while to realize the following: l...@sylvester py_count $ python Python 2.6.3 (r263:75183, Oct 26 2009, 12:34:23) [GCC 4.4.1] on linux2 Type "help", "copyright", "credits" or "license" for more information. >>> max = '5' >>> n = 5 >>> n >= max False >>> n + max Traceback (most recent call last): File "", line 1, in TypeError: unsupported operand type(s) for +: 'int' and 'str' >>> Section 5.9 Comparison describes this. Can someone give me examples of use cases TIA Hellmut -- Dr. Hellmut Weber m...@hellmutweber.de Degenfeldstraße 2 tel +49-89-3081172 D-80803 München-Schwabing mobil +49-172-8450321 please: No DOCs, no PPTs. why: tinyurl.com/cbgq -- http://mail.python.org/mailman/listinfo/python-list
Re: Prepend to logging message
Joan Miller wrote:
> On 10 ene, 10:26, Peter Otten <__pete...@web.de> wrote:
>> Joan Miller wrote:
>> > How to prepend anything to a logging message? Is possible to do it
>> > from the dictionary object (ExtraLog) or is there is that override
>> > process() [1]?
>>
>> > --
>> > class ExtraLog(object):
>>
>> > def __getitem__(self, name):
>> > if name == 'foo':
>> > result = 'testing'
>> > return result
>>
>> > def __iter__(self):
>> > keys = ['foo',]
>> > keys.extend(self.__dict__.keys())
>> > return iter(keys)
>>
>> format = "foo=%(foo)s " + logging.BASIC_FORMAT
>> logging.basicConfig(format=format)
>> logger = logging.LoggerAdapter(logging.getLogger('foo'), ExtraLog())
>> logger.error("yadda")
>>
>> Is that what you want?
>>
>> Peter
>
> I want that a message can be modified before of being logged. i.e. for
> "yadda" I would that were preppend 2 spaces. (And I want not manage
> that in the format to manage the indentation of all text)
Following Ishwor's advice:
import logging
class MyLoggerAdapter(logging.LoggerAdapter):
def process(self, msg, kwargs):
return "message->" + msg.upper(), kwargs
logging.basicConfig()
logger = MyLoggerAdapter(logging.getLogger('foo'), {})
logger.error("yadda")
Peter
--
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Re: integer and string compare, is that correct?
On Sun, Jan 10, 2010 at 4:26 AM, Hellmut Weber wrote: > Hi, > being a causal python user (who likes the language quite a lot) > it took me a while to realize the following: > > > l...@sylvester py_count $ python > Python 2.6.3 (r263:75183, Oct 26 2009, 12:34:23) > [GCC 4.4.1] on linux2 > Type "help", "copyright", "credits" or "license" for more information. max = '5' n = 5 n >= max > False n + max > Traceback (most recent call last): > File "", line 1, in > TypeError: unsupported operand type(s) for +: 'int' and 'str' > > > Section 5.9 Comparison describes this. > > Can someone give me examples of use cases The behavior of disparate types being comparable is deprecated and has been removed in Python 3.0+; don't rely upon it. (The ordering used is arbitrary but consistent) IIRC, the feature existed in prior versions to make lists containing mixed types sortable; this was found to be not all that useful and to hide what are quite arguably errors. Cheers, Chris -- http://blog.rebertia.com -- http://mail.python.org/mailman/listinfo/python-list
Re: integer and string compare, is that correct?
On Sun, Jan 10, 2010 at 4:46 AM, Chris Rebert wrote: > The behavior of disparate types being comparable is deprecated and has > been removed in Python 3.0+; don't rely upon it. Clarification: Equality testing between disparate types still works unaltered however. By "comparable", I meant >, <, >=, <= comparisons. Cheers, Chris -- http://mail.python.org/mailman/listinfo/python-list
Re: Prepend to logging message
On 10 ene, 12:36, Peter Otten <__pete...@web.de> wrote:
> Joan Miller wrote:
> > On 10 ene, 10:26, Peter Otten <__pete...@web.de> wrote:
> >> Joan Miller wrote:
> >> > How to prepend anything to a logging message? Is possible to do it
> >> > from the dictionary object (ExtraLog) or is there is that override
> >> > process() [1]?
>
> >> > --
> >> > class ExtraLog(object):
>
> >> > def __getitem__(self, name):
> >> > if name == 'foo':
> >> > result = 'testing'
> >> > return result
>
> >> > def __iter__(self):
> >> > keys = ['foo',]
> >> > keys.extend(self.__dict__.keys())
> >> > return iter(keys)
>
> >> format = "foo=%(foo)s " + logging.BASIC_FORMAT
> >> logging.basicConfig(format=format)
> >> logger = logging.LoggerAdapter(logging.getLogger('foo'), ExtraLog())
> >> logger.error("yadda")
>
> >> Is that what you want?
>
> >> Peter
>
> > I want that a message can be modified before of being logged. i.e. for
> > "yadda" I would that were preppend 2 spaces. (And I want not manage
> > that in the format to manage the indentation of all text)
>
> Following Ishwor's advice:
>
> import logging
>
> class MyLoggerAdapter(logging.LoggerAdapter):
> def process(self, msg, kwargs):
> return "message->" + msg.upper(), kwargs
>
> logging.basicConfig()
> logger = MyLoggerAdapter(logging.getLogger('foo'), {})
> logger.error("yadda")
>
> Peter
Thanks!
I had to see the code to override it correctly [1]
class LoggerAdapter_(logging.LoggerAdapter):
def __init__(self, logger, extra):
self.logger = logger
self.extra = extra
def process(self, msg, kwargs):
kwargs["extra"] = self.extra
return "message->" + msg.upper(), kwargs
[1]
http://bitbucket.org/mirror/python-trunk/src/tip/Lib/logging/__init__.py#cl-1264
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Re: integer and string compare, is that correct?
Hellmut Weber wrote: > being a causal python user (who likes the language quite a lot) > it took me a while to realize the following: > > > l...@sylvester py_count $ python > Python 2.6.3 (r263:75183, Oct 26 2009, 12:34:23) > [GCC 4.4.1] on linux2 > Type "help", "copyright", "credits" or "license" for more information. > >>> max = '5' > >>> n = 5 > >>> n >= max > False > Section 5.9 Comparison describes this. > > Can someone give me examples of use cases The use cases for an order that works across types like int and str are weak to non-existent. Implementing it was considered a mistake and has been fixed in Python 3: Python 3.1.1+ (r311:74480, Nov 2 2009, 15:45:00) [GCC 4.4.1] on linux2 Type "help", "copyright", "credits" or "license" for more information. >>> 5 > "5" Traceback (most recent call last): File "", line 1, in TypeError: unorderable types: int() > str() Checking for equality is still possible: >>> 5 == "5" False Peter -- http://mail.python.org/mailman/listinfo/python-list
"Advanced" Python programming book?
I've just finished reading a sort of beginner Python book, and I know quite a bit now but I'm looking for a book that can teach me advanced aspects of Python - code optimisation, threading, etc. Any recommendations? Cheers. -- http://mail.python.org/mailman/listinfo/python-list
Re: Prepend to logging message
On 10 ene, 13:10, Joan Miller wrote:
> On 10 ene, 12:36, Peter Otten <__pete...@web.de> wrote:
>
>
>
> > Joan Miller wrote:
> > > On 10 ene, 10:26, Peter Otten <__pete...@web.de> wrote:
> > >> Joan Miller wrote:
> > >> > How to prepend anything to a logging message? Is possible to do it
> > >> > from the dictionary object (ExtraLog) or is there is that override
> > >> > process() [1]?
>
> > >> > --
> > >> > class ExtraLog(object):
>
> > >> > def __getitem__(self, name):
> > >> > if name == 'foo':
> > >> > result = 'testing'
> > >> > return result
>
> > >> > def __iter__(self):
> > >> > keys = ['foo',]
> > >> > keys.extend(self.__dict__.keys())
> > >> > return iter(keys)
>
> > >> format = "foo=%(foo)s " + logging.BASIC_FORMAT
> > >> logging.basicConfig(format=format)
> > >> logger = logging.LoggerAdapter(logging.getLogger('foo'), ExtraLog())
> > >> logger.error("yadda")
>
> > >> Is that what you want?
>
> > >> Peter
>
> > > I want that a message can be modified before of being logged. i.e. for
> > > "yadda" I would that were preppend 2 spaces. (And I want not manage
> > > that in the format to manage the indentation of all text)
>
> > Following Ishwor's advice:
>
> > import logging
>
> > class MyLoggerAdapter(logging.LoggerAdapter):
> > def process(self, msg, kwargs):
> > return "message->" + msg.upper(), kwargs
>
> > logging.basicConfig()
> > logger = MyLoggerAdapter(logging.getLogger('foo'), {})
> > logger.error("yadda")
>
> > Peter
>
> Thanks!
>
> I had to see the code to override it correctly [1]
>
>
> class LoggerAdapter_(logging.LoggerAdapter):
>
> def __init__(self, logger, extra):
> self.logger = logger
> self.extra = extra
>
> def process(self, msg, kwargs):
> kwargs["extra"] = self.extra
> return "message->" + msg.upper(), kwargs
>
>
> [1]http://bitbucket.org/mirror/python-trunk/src/tip/Lib/logging/__init__...
Sorry! It isn't necessary to copy __init__().
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"Advanced" Python programming book?
> I've just finished reading a sort of beginner Python book, and I know > quite a bit now but I'm looking for a book that can teach me advanced > aspects of Python - code optimisation, threading, etc. > > Any recommendations? > > Cheers. Check those link: http://www.amazon.com/Beginning-Python-Visualization-Transformation-Professionals/dp/1430218436/ref=sr_1_11?ie=UTF8&s=books&qid=1263136036&sr=1-11 http://www.amazon.com/Gray-Hat-Python-Programming-Engineers/dp/1593271921/ref=sr_1_12?ie=UTF8&s=books&qid=1263136036&sr=1-12 http://www.amazon.com/Python-Cookbook-Alex-Martelli/dp/0596007973/ref=sr_1_4?ie=UTF8&s=books&qid=1263136036&sr=1-4 http://www.amazon.com/High-Performance-Python-Anthony-Lewis/dp/0596522088/ref=sr_1_14?ie=UTF8&s=books&qid=1263136082&sr=1-14 http://www.amazon.com/Natural-Language-Processing-Python-Steve/dp/0596516495/ref=sr_1_16?ie=UTF8&s=books&qid=1263136082&sr=1-16 http://www.amazon.com/Python-Scripting-Computational-Science-Engineering/dp/3540739157/ref=sr_1_17?ie=UTF8&s=books&qid=1263136082&sr=1-17 http://www.amazon.com/Expert-Python-Programming-practices-distributing/dp/184719494X/ref=sr_1_20?ie=UTF8&s=books&qid=1263136082&sr=1-20 http://www.djangobook.com/ Similar topics you can find in Google. Check python technologies, like: PyCuda, SciPy, NumPy, PyGame, Django, Pylons, Zope, TurboGears, Twisted, PyGTK, PyQt and so on. Check this link: http://www.python.org/about/apps/ and this http://wiki.python.org/moin/ Cheers :) -- http://mail.python.org/mailman/listinfo/python-list
Re: lightweight encryption of text file
On Sun, 10 Jan 2010 09:59:31 +0100, Daniel Fetchinson wrote:
> Thanks, this looks very simple too, but where is the decryption code?
> Wikipedia seems to suggest that encryption and decryption are both the
> same but running crypt on the output of crypt doesn't give back the
> original string. So probably I'm misunderstanding something.
Yes, the nature of a stream cipher :)
What you're probably doing is what I did, before I had my Aha!!! moment:
>>> arc = arcfour("password")
>>> plaintext = "attack at dawn"
>>> ciphertext = arc.crypt(plaintext)
>>> print plaintext; print ciphertext.encode("hex").upper()
attack at dawn
6371736C6E7C3F495C185629210B
>>> x = arc.crypt(ciphertext)
>>> assert x == plaintext
Traceback (most recent call last):
File "", line 1, in
AssertionError
>>> x
'\x16\xf7\xf1\xcc\xda\xb5\xe0\xbf\x0b\x13 bF\x8f'
So what's going on? Consider:
Because Arcfour uses xor for the encryption step, decryption is exactly
the same. So you only need one method to do both.
But because Arcfour stores state, calling it twice in a row doesn't give
the same result:
>>> arc.crypt("hello").encode("hex").upper()
'CAA48DE953'
>>> arc.crypt("hello").encode("hex").upper()
'03405412CA'
Arcfour is a stream cipher. When you call it twice on two different
strings, that is logically equivalent to calling it once on a single long
string made up of concatenating the two strings together. Each time you
encrypt a single character, the internal state ("self.s") changes. To
undo the change, you need the same state. The easiest way to do this is
by creating a new instance:
>>> encrypter = arcfour("password")
>>> decrypter = arcfour("password")
>>> plaintext = "attack at dawn"
>>> ciphertext = encrypter.crypt(plaintext)
>>> assert decrypter.crypt(ciphertext) == plaintext
>>>
So long as the two instances stay in lock-step (every time you use up a
byte from the keystream in one, you do the same in the other) you can use
one to decrypt the output of the other. It doesn't even really matter
which one you use:
>>> x = decrypter.crypt("Nobody expects the Spanish Inquisition!!!")
>>> encrypter.crypt(x)
'Nobody expects the Spanish Inquisition!!!'
In summary: use the arcfour class to create a stream. If you are just
encrypting, or just decrypting, you can use one stream, or as many
streams as you like, using different keys. But to do both, you need two
streams, initiated with the same key, and kept in lockstep.
The advantage of a stream cipher is that you can encrypt a text without
needing all the text at once, and then decrypt it the same way:
>>> output = []
>>> output.append(encrypt.crypt("abcdefghi"))
>>> output.append(encrypt.crypt("jklmno"))
>>> output.append(encrypt.crypt("p"))
>>> output.append(encrypt.crypt("qrstuvwxyz"))
>>> output = ''.join(output)
>>>
>>> plain = []
>>> plain.append(decrypt.crypt(output[0:20]))
>>> plain.append(decrypt.crypt(output[20:24]))
>>> plain.append(decrypt.crypt(output[24:]))
>>> ''.join(plain)
'abcdefghijklmnopqrstuvwxyz'
--
Steven
--
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[ANN] Spyder v1.0.2 released
Hi all, I'm pleased to announce here that Spyder version 1.0.2 has been released: http://packages.python.org/spyder Previously known as Pydee, Spyder (Scientific PYthon Development EnviRonment) is a free open-source Python development environment providing MATLAB-like features in a simple and light-weighted software, available for Windows XP/Vista/7, GNU/Linux and MacOS X: * advanced code editing features (code analysis, ...) * interactive console with MATLAB-like workpace (with GUI-based list, dictionary, tuple, text and array editors -- screenshots: http://packages.python.org/spyder/console.html#the-workspace) and integrated matplotlib figures * external console to open an interpreter or run a script in a separate process (with a global variable explorer providing the same features as the interactive console's workspace) * code analysis with pyflakes and pylint * search in files features * documentation viewer: automatically retrieves docstrings or source code of the function/class called in the interactive/external console * integrated file/directories explorer * MATLAB-like path management ...and more! Spyder is part of spyderlib, a Python module based on PyQt4 and QScintilla2 which provides powerful console-related PyQt4 widgets. Spyder v1.0.2 is a bugfix release: * External console: subprocess python calls were using the external console's sitecustomize.py (instead of system sitecustomize.py) * Added workaround for PyQt4 v4.6+ major bug with matplotlib * Added option to customize the way matplotlib figures are embedded (docked or floating window) * Matplotlib's "Option" dialog box is now supporting subplots * Array editor now supports complex arrays * Editor: replaced "Run selection or current line" option by "Run selection or current block" (without selection, this feature is similar to MATLAB's cell mode) * ...and a lot of minor bugfixes. - Pierre -- http://mail.python.org/mailman/listinfo/python-list
Re: lightweight encryption of text file
On Sun, 10 Jan 2010 09:59:31 +0100, Daniel Fetchinson wrote: > Thanks, this looks very simple too, but where is the decryption code? > Wikipedia seems to suggest that encryption and decryption are both the > same but running crypt on the output of crypt doesn't give back the > original string. So probably I'm misunderstanding something. The encryption is stateful (it wouldn't be very good if it wasn't), so you need to create and initialise a new arcfour instance for decryption; you can't re-use the existing instance. -- http://mail.python.org/mailman/listinfo/python-list
Re: lightweight encryption of text file
On Sun, 10 Jan 2010 15:30:12 +, Steven D'Aprano wrote: >> Thanks, this looks very simple too, but where is the decryption code? >> Wikipedia seems to suggest that encryption and decryption are both the >> same but running crypt on the output of crypt doesn't give back the >> original string. So probably I'm misunderstanding something. > > Yes, the nature of a stream cipher :) It isn't limited to stream ciphers. You would have the same issue for a block cipher with chaining (i.e. *not* ECB mode). -- http://mail.python.org/mailman/listinfo/python-list
Re: integer and string compare, is that correct?
Hellmut Weber wrote: >> being a causal python user (who likes the language quite a lot) >> it took me a while to realize the following: >> >>> max = '5' >> >>> n = 5 >> >>> n >= max >> False > >> Section 5.9 Comparison describes this. >> >> Can someone give me examples of use cases Peter Otten wrote: > The use cases for an order that works across types like int and str are weak > to non-existent. Implementing it was considered a mistake and has been fixed > in Python 3: 5 > "5" > Traceback (most recent call last): > File "", line 1, in > TypeError: unorderable types: int() > str() If you actually need to perform comparisons across types, you can rely upon the fact that tuple comparisons are non-strict and use e.g.: > a = 5 > b = '5' > (type(a).__name__, a) < (type(b).__name__, b) True > (type(a).__name__, a) > (type(b).__name__, b) False The second elements will only be compared if the first elements are equal (i.e. the values have the same type). -- http://mail.python.org/mailman/listinfo/python-list
Re: "Advanced" Python programming book?
Ryniek90 wrote: I've just finished reading a sort of beginner Python book, and I know quite a bit now but I'm looking for a book that can teach me advanced aspects of Python - code optimisation, threading, etc. Any recommendations? Cheers. Check those link: http://www.amazon.com/Beginning-Python-Visualization-Transformation-Professionals/dp/1430218436/ref=sr_1_11?ie=UTF8&s=books&qid=1263136036&sr=1-11 http://www.amazon.com/Gray-Hat-Python-Programming-Engineers/dp/1593271921/ref=sr_1_12?ie=UTF8&s=books&qid=1263136036&sr=1-12 http://www.amazon.com/Python-Cookbook-Alex-Martelli/dp/0596007973/ref=sr_1_4?ie=UTF8&s=books&qid=1263136036&sr=1-4 http://www.amazon.com/High-Performance-Python-Anthony-Lewis/dp/0596522088/ref=sr_1_14?ie=UTF8&s=books&qid=1263136082&sr=1-14 http://www.amazon.com/Natural-Language-Processing-Python-Steve/dp/0596516495/ref=sr_1_16?ie=UTF8&s=books&qid=1263136082&sr=1-16 http://www.amazon.com/Python-Scripting-Computational-Science-Engineering/dp/3540739157/ref=sr_1_17?ie=UTF8&s=books&qid=1263136082&sr=1-17 http://www.amazon.com/Expert-Python-Programming-practices-distributing/dp/184719494X/ref=sr_1_20?ie=UTF8&s=books&qid=1263136082&sr=1-20 http://www.djangobook.com/ Similar topics you can find in Google. Check python technologies, like: PyCuda, SciPy, NumPy, PyGame, Django, Pylons, Zope, TurboGears, Twisted, PyGTK, PyQt and so on. Check this link: http://www.python.org/about/apps/ and this http://wiki.python.org/moin/ Cheers :) some good books.. i might add this to the list http://www.amazon.com/Python-Essential-Reference-David-Beazley/dp/0672329786/ref=pd_sim_b_2 -- http://mail.python.org/mailman/listinfo/python-list
Re: lightweight encryption of text file
>> Thanks, this looks very simple too, but where is the decryption code?
>> Wikipedia seems to suggest that encryption and decryption are both the
>> same but running crypt on the output of crypt doesn't give back the
>> original string. So probably I'm misunderstanding something.
>
> Yes, the nature of a stream cipher :)
>
> What you're probably doing is what I did, before I had my Aha!!! moment:
>
>
arc = arcfour("password")
plaintext = "attack at dawn"
ciphertext = arc.crypt(plaintext)
print plaintext; print ciphertext.encode("hex").upper()
> attack at dawn
> 6371736C6E7C3F495C185629210B
x = arc.crypt(ciphertext)
assert x == plaintext
> Traceback (most recent call last):
> File "", line 1, in
> AssertionError
x
> '\x16\xf7\xf1\xcc\xda\xb5\xe0\xbf\x0b\x13 bF\x8f'
>
>
> So what's going on? Consider:
>
> Because Arcfour uses xor for the encryption step, decryption is exactly
> the same. So you only need one method to do both.
>
> But because Arcfour stores state, calling it twice in a row doesn't give
> the same result:
>
arc.crypt("hello").encode("hex").upper()
> 'CAA48DE953'
arc.crypt("hello").encode("hex").upper()
> '03405412CA'
>
>
> Arcfour is a stream cipher. When you call it twice on two different
> strings, that is logically equivalent to calling it once on a single long
> string made up of concatenating the two strings together. Each time you
> encrypt a single character, the internal state ("self.s") changes. To
> undo the change, you need the same state. The easiest way to do this is
> by creating a new instance:
>
>
encrypter = arcfour("password")
decrypter = arcfour("password")
plaintext = "attack at dawn"
ciphertext = encrypter.crypt(plaintext)
assert decrypter.crypt(ciphertext) == plaintext
>
>
> So long as the two instances stay in lock-step (every time you use up a
> byte from the keystream in one, you do the same in the other) you can use
> one to decrypt the output of the other. It doesn't even really matter
> which one you use:
>
x = decrypter.crypt("Nobody expects the Spanish Inquisition!!!")
encrypter.crypt(x)
> 'Nobody expects the Spanish Inquisition!!!'
>
>
> In summary: use the arcfour class to create a stream. If you are just
> encrypting, or just decrypting, you can use one stream, or as many
> streams as you like, using different keys. But to do both, you need two
> streams, initiated with the same key, and kept in lockstep.
>
> The advantage of a stream cipher is that you can encrypt a text without
> needing all the text at once, and then decrypt it the same way:
>
output = []
output.append(encrypt.crypt("abcdefghi"))
output.append(encrypt.crypt("jklmno"))
output.append(encrypt.crypt("p"))
output.append(encrypt.crypt("qrstuvwxyz"))
output = ''.join(output)
plain = []
plain.append(decrypt.crypt(output[0:20]))
plain.append(decrypt.crypt(output[20:24]))
plain.append(decrypt.crypt(output[24:]))
''.join(plain)
> 'abcdefghijklmnopqrstuvwxyz'
Thanks Steven, this was very helpful!
Cheers,
Daniel
--
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--
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Re: lightweight encryption of text file
Nobody writes: > RC4 (aka ArcFour) is quite trivial to implement, and better than inventing > your own cipher or using a Vignere: ... That's a cute implementation, but it has no authentication and doesn't include any randomness, which means if you use the same key for two inputs, there is a security failure (xor'ing the two ciphertexts reveals the xor of the plaintexts). It also looks rather slow. I don't make any guarantees about p3.py, but it has been reviewed by several experts and appears to be reasonably sound for the type of casual use being discussed here, and it is tuned for speed (given the implementation constraints). For more demanding purposes, you should use a more serious library like one of the OpenSSL wrappers. -- http://mail.python.org/mailman/listinfo/python-list
Academic Question
Hi;
The following code that works:
#! /usr/bin/python
import string
import cgitb; cgitb.enable()
import cgi
import MySQLdb
import sys,os
from sets import Set
import fpformat
cwd = os.getcwd()
sys.path.append(cwd)
from login import login
from particulars import ourOptions
form = cgi.FieldStorage()
store = form.getfirst('store')
cat = form.getfirst('cat')
id = form.getfirst('id')
patientID = form.getfirst('patientID')
try:
browser = form.getfirst('browser', 'all')
except:
browser = headers()
os.chdir('%s/..' % cwd)
sys.path.append(os.getcwd())
from templateFrame import top, bottom
os.chdir(cwd)
Why doesn't it work if I move the bottom imports to the top? The form values
get lost, even though I chdir to cwd.
TIA,
beno
--
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http://logos.13gems.com/
--
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Re: Something More Elegant
On Sat, Jan 9, 2010 at 3:00 PM, Stephen Hansen wrote:
> On Sat, Jan 9, 2010 at 7:15 AM, Victor Subervi wrote:
>
>> On Sat, Jan 9, 2010 at 9:35 AM, Steve Holden wrote:
>>
>>> But we are now in the realm of theory as far as you are concerned, since
>>> you have already stated several times that you aren't interested in
>>> correcting your design until after you have got the current mess into
>>> production. So good luck with that.
>>>
>>
>> And if you were in my shoes, I'm sure you'd do the same thing.
>
>
> ... Really, no, he wouldn't :)
>
Let's not argue an academic point.
> We're not all just hobbyists here who only do work for random open source
> projects. A lot of us are professionals who actually do have clients,
> actually do have deadlines, actually do have an understanding for production
> requirements. Getting something into production as soon as possible is
> certainly an important goal in commercial work. But it is not the only goal.
> Proper database design is very important because if you don't do it, you'll
> actually end up usually wasting *more* time and effort then if you just bite
> the bullet and fix it now.
>
Clearly. That's why when it was pointed out to me, I jumped on it.
>
> Proper database design -- in particular in your case, not having multiple
> tables with various names that even need "%sThis" or "%sThat", and using
> parameterized queries to access those tables, is really important. It will
> save you time, it will save you effort, and it'll save you money-- because
> /not/ doing it is among other things, a major security risk. Getting code
> out fast and now is a noble goal in commercial projects, getting code out
> which is by design prone to attacks by hackers is negligence.
>
You're preaching to the choir ;) Read the above. The only exception to this
is putting all store stuff in the same table. The columns of each store
table are different and automatically created through what I believe are
called "mixins".
>
> Well, it *is* working now :)) And I am interested in cleaning this up. I
>> should probably start with the matter of databases, since that's something I
>> won't be able to easily change once clients actually start entering data.
>> Please share with me any further concepts or questions to get me thinking
>> how to redesign the databases.
>>
>
> The next thing to do is to re-do your SQL queries. You should never do
> string interpolation, e.g:
>
> SQL="SELECT x FROM y WHERE z = %s" % (arg,)
> cur.execute(SQL)
>
> If you have done the first step, your tables always have a set names so you
> never need to interpolate to do the queries-- and then at this point, under
> no circumstances ever, ever-- consider this a law that you will get fined
> for violation-- use string interpolation to generate your queries.
>
> Instead, do:
>
> cur.execute("SELECT x FROM y WHERE z = %s", (arg,))
>
> That looks really similar, but is lightyears away. Its very unfortunate
> that some database drivers use 'format' as the paramstyle because it
> confuses issues, but the two effects are very different. In one, Python is
> just munging together and creating a new string. In the other, the database
> driver is doing a few things. Its analyzing the query, its storing it (often
> caching it, which speeds up further executions of that query), etc, etc, and
> then finally its seeing that you are passing arguments into it, and it is
> -safely- binding those arguments into the expression; this prevents SQL
> Injection attacks. You can use interpolation and prevent injection if you
> -meticulously- check -every- string that comes from the user, and -never-
> trust it (even if that string was written out to a hidden and
> legitimate users have no way to alter, because illegitimate users will alter
> it anyways). Or you can use parameterized queries and just avoid it, while
> getting plenty of other benefits as well.
>
>
> At work, we had a third-party package that we re-sold as part of our
> offering, and glancing over its source, I noticed something. It did, in
> essence to check login:
>
> cur.execute("SELECT user_id FROM usertable WHERE username = '%s' AND
> password = '%s' % (username, password))
>
> I blinked, and emailed them to point out the problem. I suggested they log
> in as:
>
> Username = dummyuser
> Password = '; DROP usertable
>
> You see, when using interpolation, the string that got sent to the database
> was:
>
> SELECT user_id FROM usertable WHERE username = 'dummyuser' AND password
> = ''; DROP usertable
>
> And thus, from the login screen of this app-- I destroyed their
> environment.
>
> Its sort of important that you not put code out into production which is
> susceptible to such things. Your clients will not at all appreciate it if
> and when some hacker discovers it and destroys their site, loosing them
> money. But even beyond that, there are many other benefits to just doing
> this right. You want to, believe me. Now, before yo
Re: integer and string compare, is that correct?
Somebody wrote: > If you actually need to perform comparisons across types, you can rely > upon the fact that tuple comparisons are non-strict and use e.g.: > > > a = 5 > > b = '5' > > (type(a).__name__, a) < (type(b).__name__, b) > True > > (type(a).__name__, a) > (type(b).__name__, b) > False > > The second elements will only be compared if the first elements are equal > (i.e. the values have the same type). The same type *name*. To play it safe you'll have to compare the id, too: >>> items = [] >>> for i in range(2): ... class A: pass ... items.append(A()) ... >>> sorted(items, key=lambda a: (type(a).__name__, a)) Traceback (most recent call last): File "", line 1, in TypeError: unorderable types: A() < A() >>> sorted(items, key=lambda a: (type(a).__name__, id(type(a)), a)) [<__main__.A object at 0x14dfbd0>, <__main__.A object at 0x14dfc50>] Peter -- http://mail.python.org/mailman/listinfo/python-list
Re: problem with cheetah
In article <0fd84b05-cf12-485b-a14e-608e47679...@s20g2000yqd.googlegroups.com>, mlowicki wrote: > >Hi!, i get such error when I try to install cheetah: Probably better to ask on the Cheetah list: https://lists.sourceforge.net/lists/listinfo/cheetahtemplate-discuss -- Aahz (a...@pythoncraft.com) <*> http://www.pythoncraft.com/ "If you think it's expensive to hire a professional to do the job, wait until you hire an amateur." --Red Adair -- http://mail.python.org/mailman/listinfo/python-list
Milliseconds in logging format
How the logging '%(asctime)s' [1] specifier to gets the millisecond portion of the time if there is not a directive to get it from the time module [2] ? "The date format string follows the requirements of strftime()" [1] http://docs.python.org/library/logging.html#basic-example [2] http://docs.python.org/library/time.html#time.strftime -- http://mail.python.org/mailman/listinfo/python-list
Re: Academic Question
Victor Subervi wrote:
Hi;
The following code that works:
#! /usr/bin/python
import string
import cgitb; cgitb.enable()
import cgi
import MySQLdb
import sys,os
from sets import Set
import fpformat
cwd = os.getcwd()
sys.path.append(cwd)
from login import login
from particulars import ourOptions
form = cgi.FieldStorage()
store = form.getfirst('store')
cat = form.getfirst('cat')
id = form.getfirst('id')
patientID = form.getfirst('patientID')
try:
browser = form.getfirst('browser', 'all')
except:
browser = headers()
A bare except, and if an exception _does_ occur, they'll be a NameError
because 'headers' isn't defined.
os.chdir('%s/..' % cwd)
sys.path.append(os.getcwd())
from templateFrame import top, bottom
os.chdir(cwd)
Why doesn't it work if I move the bottom imports to the top? The form
values get lost, even though I chdir to cwd.
I try to avoid changing the directory.
--
http://mail.python.org/mailman/listinfo/python-list
Re: lightweight encryption of text file
Not sure why in the world you would homebrew something like this- a small dependency isn't that bad, and aes can be pretty simple to use. Might as well go for the industrial strength approach. Geremy Condra -- http://mail.python.org/mailman/listinfo/python-list
Re: Milliseconds in logging format
On 10-1-2010 20:04, Joan Miller wrote: How the logging '%(asctime)s' [1] specifier to gets the millisecond portion of the time if there is not a directive to get it from the time module [2] ? "The date format string follows the requirements of strftime()" [1] http://docs.python.org/library/logging.html#basic-example [2] http://docs.python.org/library/time.html#time.strftime It appends them to the string that strftime() returned. If you set a custom datefmt, it will stop doing this and you'll have to use %(msecs) in your log format to get them back. See the source, Lib/logging/__init__.py around line 400. (Python 2.6.4) -irmen -- http://mail.python.org/mailman/listinfo/python-list
"Bad file descriptor" in HTTPServer using Multiprocessing.
I have a Python multiprocessing application where a master process
starts server sub-processes and communicates with them via Pipes; that
works very well. But one of the subprocesses, in turn, starts a
collection of HTTPServer 'workers' (almost exactly as demonstrated in
the docs). This works perfectly so long as the subprocess that
starts the HTTPServer workers is the *first* process started by the
master process. Otherwise the HTTPServer's serve_forever immediately
abends with: "(9, 'Bad file descriptor')"
I'm confused why the order of starting the processes matter, especially
given that the HTTPServer's are start in a subprocess of a subprocess.
The master doesn't do much of anything between starting each subprocess
(which it does in a loop; identify all the subprocesses to start, and
start them.).
subprocess
..
self._httpd = HTTPServer((HTTP_HOST, HTTP_PORT), HTTPRequestHandler)
print 'HTTPServer created.'
for i in range(10):
p = multiprocessing.Process(target=serve_forever,
args=(self._httpd, i, self))
self._workers.append(p)
p.start()
.
def serve_forever(server, i, control):
print 'coils.http starting HTTP worker #{0}'.format(i)
try:
server.serve_forever()
except KeyboardInterrupt:
pass
except Exception, e:
control.log.exception(e)
print 'coils.http worker #{0} abended with exception.'.format(i)
print e
return
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How to use list type generated by SWIG?
I am writing a small script to manage my ipod. I am using the python
bindings for libgpod. I have never used swig, or used python to
program against a c/c++ library.
I can get the library to find my ipod, and parse its DB format, but
I'm not sure how to interact with the types that some of the functions
return, specifically a Swig Glist (gtk's doubly-linked list)
import gpod
db = gpod.itdb_parse('/media/ipod', None)
print db.tracks
>>>
Glist is not iterable or subscriptable. It contains a 'next' function
which always seems to return None after printing "swig/python detected
a memory leak of type 'GList *', no destructor found." to the console.
How can I interact with this list?
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Re: lightweight encryption of text file
geremy condra writes: > Not sure why in the world you would homebrew something like this- a > small dependency isn't that bad, and aes can be pretty simple to use. > Might as well go for the industrial strength approach. In my experience, 1) small dependencies ARE that bad, since they mean you have to develop and test on every platform that you want your code to run on; 2) using a serious library requires quite a bit of knowledge and decision-making which not everyone is equipped to do. "AES" is not so simple to use unless you know what you're doing in terms of modes, nonces, etc. Having supported this kind of package in a commercial setting in the past, IMO, for the sort of (common) application in question, it's best to keep things as simple as possible and supply a single interface that provides encryption, authentication, and random initialization all in one call. The cost is a little bit of ciphertext bloat, but it prevents all kinds of security failures frequently overlooked by novices. I'd like it a lot if the Python stdlib could include a serious cryptography module. That was rejected for regulatory reasons several years ago, but maybe things are changing enough that the issue can be revisited sometime. -- http://mail.python.org/mailman/listinfo/python-list
Re: Microsoft Office Word and Python (Win XP)
so does anyone know how I could do this? -- http://mail.python.org/mailman/listinfo/python-list
Re: getopt not raising exception
Matt Nordhoff wrote: > BTW: Checked out optparse? It's bigger and sexier! Thanks for the tip. Works a treat. -- Matt -- http://mail.python.org/mailman/listinfo/python-list
Re: getopt not raising exception
> Matt Nordhoff wrote: > > BTW: Checked out optparse? It's bigger and sexier! If you're doing things with positional arguments, you should consider using argparse (http://argparse.googlecode.com/svn/tags/r101/doc/index.html). It's like optparse, but (much) better. Cheers, Emm -- http://mail.python.org/mailman/listinfo/python-list
class viewer ?
hello, I'd like to have a class viewer, something different from pydoc, and I wonder if someone has made something similar. from the given class, it's ancestors and it's derived classes, I'ld like to get the following information in a tree like structure: - the file were the class is definied - the attributes, split in inherited / created / overriden - the methodes, split in inherited / created / overriden - the files were instances of the class are created - and probably I forget a few any suggestions ? thanks, Stef Mientki -- http://mail.python.org/mailman/listinfo/python-list
setTextAlignment function Qtablewidget PyQt
Hey! I am trying to align contents of some table cells but find the code below working for some fields and not for others. I am stuck as to why this is happening. Help will be gretly appreciated! setTextAlignment(QtCore.Qt.AlignVCenter) Cheers Zabin -- http://mail.python.org/mailman/listinfo/python-list
sys.stdout vs. sys.stderr
In Python 3.1 is there any difference in the buffering behavior of the initial sys.stdout and sys.stderr streams? They are both line_buffered and stdout doesn't seem to use a larger-grain buffering, so they seem to be identical with respect to buffering. Were they different at some earlier point in Python's evolution? -- http://mail.python.org/mailman/listinfo/python-list
Re: setTextAlignment function Qtablewidget PyQt
On Jan 11, 1:10 pm, Zabin wrote: > Hey! > > I am trying to align contents of some table cells but find the code > below working for some fields and not for others. I am stuck as to why > this is happening. Help will be gretly appreciated! > > setTextAlignment(QtCore.Qt.AlignVCenter) > > Cheers > Zabin Figured it out! It was just the '\n' character being read with the line from the text file that messed up the formatting. just needed to use the line.strip() function before passing it to the table as a table widget item. -- http://mail.python.org/mailman/listinfo/python-list
Fractional Hours from datetime?
Maybe there's a more elegant way to do this. I want to express the result of datetime.datetime.now() in fractional hours. Here's one way. dt=datetime.datetime.now() xtup = dt.timetuple() h = xtup[3]+xtup[4]/60.0+xtup[5]/3600.00+xtup[6]/10**6 # now is in fractions of an hour -- http://mail.python.org/mailman/listinfo/python-list
Python Goldmine has been updated: http://preciseinfo.org/Convert/index_Convert_Python.html
Python Goldmine collection contains the extensive collection of articles going back several years. It includes thousands of code examples and expert discussions on all major topics. The information is organized by relevant topics, covered by the corresponding chapters. The information was filtered with sophisticated filters and vast majority of artilces with little relevance have been filtered out. If you have any specific requests for some new chapters to be added and it is of interest to others, please post your requests on this thread. If anyone feels he has above average level of competence, or can reccommend someone who posts on this group, you may request to be included in the expert chapters. The Python Goldmine is at: http://preciseinfo.org/Convert/index_Convert_Python.html -- Programmer's Goldmine collections: http://preciseinfo.org Tens of thousands of code examples and expert discussions on C++, MFC, VC, ATL, STL, templates, Java, Python, Javascript, PHP, organized by major topics of language, tools, methods, techniques. -- http://mail.python.org/mailman/listinfo/python-list
Re: Introspection
Thanks Miki and Jason. I knew it could be done :-) -- http://mail.python.org/mailman/listinfo/python-list
Re: Manipulating pointers in C using ctypes
Thanks for valuable answers. Both solutions work and I understand my mistake. Best regards, Daniel -- http://mail.python.org/mailman/listinfo/python-list
Re: Microsoft Office Word and Python (Win XP)
? -- http://mail.python.org/mailman/listinfo/python-list
Re: Microsoft Office Word and Python (Win XP)
no idea :-( -- http://mail.python.org/mailman/listinfo/python-list
Re: Computer Music Toolkit (CMT) ?
On 1/10/2010 4:15 AM, Peter Billam wrote: Greetings. Is there a way to get at the Computer Music Toolkit (CMT) http://www.ladspa.org/cmt/ functionality from Python (Python3 in my case) ? You can access compiled C shared libraries most easily via the ctypes module. Searching Python CMT "Computer Music Toolkit" (following Stefan's suggestion) returns a few hits that might be useful. Searching PyPI for CMT does not turn up any relevant packages, so if you do develop a ctypes wrapping, consider contributing it. Terry Jan Reedy -- http://mail.python.org/mailman/listinfo/python-list
Re: Python Goldmine has been updated: http://preciseinfo.org/Convert/index_Convert_Python.html
On 1/8/2010 11:50 AM, tanix wrote: Python Goldmine collection contains the extensive collection of articles going back several years. It includes thousands of code examples and expert discussions on all major topics. The information is organized by relevant topics, covered by the corresponding chapters. The information was filtered with sophisticated filters and vast majority of artilces with little relevance have been filtered out. If you have any specific requests for some new chapters to be added and it is of interest to others, please post your requests on this thread. If anyone feels he has above average level of competence, or can reccommend someone who posts on this group, you may request to be included in the expert chapters. The Python Goldmine is at: http://preciseinfo.org/Convert/index_Convert_Python.html -- Programmer's Goldmine collections: http://preciseinfo.org Tens of thousands of code examples and expert discussions on C++, MFC, VC, ATL, STL, templates, Java, Python, Javascript, PHP, organized by major topics of language, tools, methods, techniques. This site pops up spam windowns. One was blocked, one managed to bypass the popup blocker. Tnis is not friendly behaviour. Some categories have 100s of entries. Better, I think, to use a search engine such as Google with more specific search terms and a snippet of context for each result. tjr -- http://mail.python.org/mailman/listinfo/python-list
Re: Python Goldmine has been updated: http://preciseinfo.org/Convert/index_Convert_Python.html
Terry Reedy wrote: > On 1/8/2010 11:50 AM, tanix wrote: >> Python Goldmine collection contains the extensive collection of articles >> going back several years. It includes thousands of code >> examples and expert discussions on all major topics. >> >> The information is organized by relevant topics, covered >> by the corresponding chapters. >> >> The information was filtered with sophisticated filters and vast >> majority of artilces with little relevance have been filtered out. >> >> If you have any specific requests for some new chapters to be added >> and it is of interest to others, please post your requests on this >> thread. >> >> If anyone feels he has above average level of competence, or can >> reccommend someone who posts on this group, you may request to be >> included in the expert chapters. >> >> The Python Goldmine is at: >> >> http://preciseinfo.org/Convert/index_Convert_Python.html >> >> -- >> Programmer's Goldmine collections: >> >> http://preciseinfo.org >> >> Tens of thousands of code examples and expert discussions on >> C++, MFC, VC, ATL, STL, templates, Java, Python, Javascript, PHP, >> organized by major topics of language, tools, methods, techniques. > > This site pops up spam windowns. One was blocked, one managed to bypass > the popup blocker. Tnis is not friendly behaviour. > > Some categories have 100s of entries. Better, I think, to use a search > engine such as Google with more specific search terms and a snippet of > context for each result. > Because I habitually run the NoScript extension to Firefox the popups didn't appear, but there didn't seem to be any original content on this site. Google continues to be your friend. regards Steve -- Steve Holden +1 571 484 6266 +1 800 494 3119 PyCon is coming! Atlanta, Feb 2010 http://us.pycon.org/ Holden Web LLC http://www.holdenweb.com/ UPCOMING EVENTS:http://holdenweb.eventbrite.com/ -- http://mail.python.org/mailman/listinfo/python-list
Re: Python Goldmine has been updated: http://preciseinfo.org/Convert/index_Convert_Python.html
Steve Holden wrote: [...] > Because I habitually run the NoScript extension to Firefox the popups > didn't appear, but there didn't seem to be any original content on this > site. Google continues to be your friend. > And dammit, why didn't I think to strip the links out instead of creating yet one more link to it? Sorry ... regards Steve -- Steve Holden +1 571 484 6266 +1 800 494 3119 PyCon is coming! Atlanta, Feb 2010 http://us.pycon.org/ Holden Web LLC http://www.holdenweb.com/ UPCOMING EVENTS:http://holdenweb.eventbrite.com/ -- http://mail.python.org/mailman/listinfo/python-list
Re: lightweight encryption of text file
On Sun, 10 Jan 2010 08:54:51 -0800, Paul Rubin wrote: > Nobody writes: >> RC4 (aka ArcFour) is quite trivial to implement, and better than inventing >> your own cipher or using a Vignere: ... > > That's a cute implementation, but it has no authentication and doesn't > include any randomness, which means if you use the same key for two > inputs, there is a security failure (xor'ing the two ciphertexts reveals > the xor of the plaintexts). Right. RC4 is a cipher, not a cryptosystem. But, yeah, the OP needs to be aware of the difference (and probably isn't, yet). So to take that a step further ... The key passed to arcfour.schedule() shouldn't be re-used. If you need to encrypt multiple files, use a different key for each. If you want to encrypt multiple files with the same "password", generate a unique key by hashing a combination of the password and a random salt (e.g. from /dev/random), and prepend the salt to the beginning of the stream. To decrypt, extract the salt from the stream to generate the key. If you need to verify the data, append a hash of the ciphertext (a hash of the plaintext would allow an attacker to confirm a guessed plaintext or to confirm that two files contain the same plaintext). Stream ciphers are vulnerable to replacement attacks: (p1 xor r) xor (p1 xor p2) == (p2 xor r) So if you can guess any part of the plaintext p1, you can replace it with alternative plaintext p2 without needing to decrypt/encrypt or knowing anything about the pad r. Also, if this is for something important, I'd be concerned about how to protect the key. That's hard enough to do in C, let alone in Python. > It also looks rather slow. Any kind of bulk binary data processing in pure Python is slow. The code was written mainly for simplicity, e.g. using generators means that you don't have to deal with buffer sizes. Replacing " % 256" with " & 255" might be worthwhile. > I don't make > any guarantees about p3.py, but it has been reviewed by several experts > and appears to be reasonably sound for the type of casual use being > discussed here, and it is tuned for speed (given the implementation > constraints). For more demanding purposes, you should use a more > serious library like one of the OpenSSL wrappers. The OP specifically wanted to avoid third-party libraries. -- http://mail.python.org/mailman/listinfo/python-list
Re: lightweight encryption of text file
On Sun, 10 Jan 2010 12:26:05 -0800, Paul Rubin wrote: > I'd like it a lot if the Python stdlib could include a serious > cryptography module. And I'd like a truckload of gold ;) Right now, even asking for HTTPS support is too much to ask. Heck, even asking for the fake HTTPS support to be identified as such is too much, apparently. -- http://mail.python.org/mailman/listinfo/python-list
Re: lightweight encryption of text file
Nobody wrote: > On Sun, 10 Jan 2010 12:26:05 -0800, Paul Rubin wrote: > >> I'd like it a lot if the Python stdlib could include a serious >> cryptography module. > > And I'd like a truckload of gold ;) > > Right now, even asking for HTTPS support is too much to ask. Heck, > even asking for the fake HTTPS support to be identified as such is too > much, apparently. > No, Paul, nobody will complain if you *ask* ... A question I've been asking myself quite a lot recently is how the PSF could, were funding to be available, direct the development of Python in specific directions, and what those directions should be. Unfortunately there are probably as many answers as Python programmers in terms of the priorities to be adopted. regards Steve -- Steve Holden +1 571 484 6266 +1 800 494 3119 PyCon is coming! Atlanta, Feb 2010 http://us.pycon.org/ Holden Web LLC http://www.holdenweb.com/ UPCOMING EVENTS:http://holdenweb.eventbrite.com/ -- http://mail.python.org/mailman/listinfo/python-list
Re: Fractional Hours from datetime?
How about: import time arizona_utc_offset = -7.00 h = (time.time() / 3600 + arizona_utc_offset) % 24 dt.timetuple()[6] is the day of the week; struct tm_time doesn't include a sub-second field. On Jan 10, 10:28 am, "W. eWatson" wrote: > Maybe there's a more elegant way to do this. I want to express the > result of datetime.datetime.now() in fractional hours. > > Here's one way. > > dt=datetime.datetime.now() > xtup = dt.timetuple() > h = xtup[3]+xtup[4]/60.0+xtup[5]/3600.00+xtup[6]/10**6 > # now is in fractions of an hour -- http://mail.python.org/mailman/listinfo/python-list
Re: interactive terminal in Ubuntu Linux : libreadline5-dev works only in Python 2.6 not 3.1
On Sat, 9 Jan 2010 16:48:52 -0800 (PST), casevh wrote: >On Jan 9, 3:10 pm, pdlem...@earthlink.net wrote: >> On Sat, 9 Jan 2010 13:27:07 -0800 (PST), casevh >> wrote: > >1) Try the commands again. Make sure all the "./configure" options are >on one line. Make sure to do "sudo make altinstall". (Don't use "sudo >make install"; it will give your version of Python the name "python" >and that can cause confusion on your system.) > >2) Move your applications to another directory. > >3) Try running "python3.1" while you are in that directory. > >If this doesn't work, report back on the error messages you receive. > Thanks casevh for your time & patience. The ./configure . . . was a "continuous" line , although it ran over to next line even on 132 char wide terminal because of names of system & dir. I was careful with the spaces and hyphens. In my reply the "make install" was a typo , I did run make altinstall. Moved all my code to pycode dir on my home directory. Removed all files from /usr/local/lib/python3.1/dlmodules and removed that dir. Twice ran the recompile : make distclean ./configure --prefix=/usr/local --with-computed-gotos --with-wide-unicode <^ one space> make sudo make altinstall After each reinstall had same problems : cannot import random or any code using it, although random.py is in Lib : Traceback File "", line 1, in File "random.py", line 46, in import collections as _collections File "collections.py", line 9 in from _collections import deque, default dict ImportError: /usr/local/lib/python3.1/lib-dynload/collections.so: undefined symbol: PyUnicodeUCS4_FromString After second reinstall today I also found that a module importing "time" would not run. Likewise could not import time at >>> . Same error, ending : undefined symbol: PyUnicode UCS4_FromString And my original problem still there : fouled up keys in interactive terminal. Seems minor now ; ) Should I try to remove everything and reopen the tarball ? Dave WB3DWE, central Texas -- http://mail.python.org/mailman/listinfo/python-list
Re: Fractional Hours from datetime?
Here's an improvement in case you want your code to work outside of Arizona: from time import time, timezone h = ((time() - timezone) / 3600) % 24 On Jan 10, 9:04 pm, Austyn wrote: > How about: > > import time > arizona_utc_offset = -7.00 > h = (time.time() / 3600 + arizona_utc_offset) % 24 > > dt.timetuple()[6] is the day of the week; struct tm_time doesn't > include a sub-second field. > > On Jan 10, 10:28 am, "W. eWatson" wrote: > > > > > Maybe there's a more elegant way to do this. I want to express the > > result of datetime.datetime.now() in fractional hours. > > > Here's one way. > > > dt=datetime.datetime.now() > > xtup = dt.timetuple() > > h = xtup[3]+xtup[4]/60.0+xtup[5]/3600.00+xtup[6]/10**6 > > # now is in fractions of an hour -- http://mail.python.org/mailman/listinfo/python-list
Re: lightweight encryption of text file
Steve Holden writes: >> Right now, even asking for HTTPS support is too much to ask. Heck, >> even asking for the fake HTTPS support to be identified as such is too >> much, apparently. >> > No, Paul, nobody will complain if you *ask* ... Er, that wasn't me... > A question I've been asking myself quite a lot recently is how the PSF > could, were funding to be available, direct the development of Python in > specific directions,... Crypto in the stdlib is not a matter of funding or (technical) priorities. It's a policy issue; the maintainers were (at least as of a few years ago) concerned about legal restrictions on crypto in some jurisdictions causing problems with distributing Python if it included crypto. I know that other systems (Java, Mozilla, etc) include crypto but they may have had to jump through some hoops for that purpose. -- http://mail.python.org/mailman/listinfo/python-list
Re: lightweight encryption of text file
Nobody writes: > But, yeah, the OP needs to be aware of the difference (and probably isn't, > yet). So to take that a step further ... > The key passed to arcfour.schedule() shouldn't be re-used > If you need to verify the data, append a hash of the ciphertext ... > If you want to encrypt multiple files with the same "password", > generate a unique key by hashing a combination of the password and a > random salt (e.g. from /dev/random)... Yep, a whole lot of stuff that's easy to get wrong if it's left to the user (for example, you mean "a MAC of the ciphertext", not "a hash of the ciphertext"), and a lot of extra work even if the user gets it right. It's simplest for the library to provide a single interface that does all of it. >> It also looks rather slow. > > Any kind of bulk binary data processing in pure Python is slow. Well, slow is a relative term, but p3.py is about 5x faster than the fastest pure-Python rc4 implementation that I compared it to. Its heavy lifting is done by the SHA and array modules, that are written in C. -- http://mail.python.org/mailman/listinfo/python-list
Re: py2exe "for loop" hangs in compiled program
In article , p_tierchen <1...@sms.at> wrote: > >the application is an interface to a sqlite database and stores image >metadata (such as year, event, photographer, people on image etc.). i >use pyqt4 for the interface and developed this application on a linux >platform (python 2.5.4). friends of mine liked what i have done an want >it for their windows computers. so i setup a test system (win XP and >python 2.6.?). copying the code to this system and starting it: works >as intended. however they complain python whats this, this is sooo >complicated etc. so i took refuge in using py2exe, planing to give them >a zip compressed archive ... testing this option i found out that on >the surface all looks nice (GUI and functions etc) however: extending >to "larger" datasets (>~50 images) some of the for loops stop after >some time. https://lists.sourceforge.net/lists/listinfo/py2exe-users -- Aahz (a...@pythoncraft.com) <*> http://www.pythoncraft.com/ "If you think it's expensive to hire a professional to do the job, wait until you hire an amateur." --Red Adair -- http://mail.python.org/mailman/listinfo/python-list
Re: How to validate the __init__ parameters
In article ,
Jean-Michel Pichavant wrote:
>
>class A:
>def __init__(self, foo = None, bar = None):
>if len(foo) > 5:
> raise ValueError('foo cannot exceed 5 characters')
Bad Idea -- what happens when foo is None?
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until you hire an amateur." --Red Adair
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Re: lightweight encryption of text file
Paul Rubin wrote: > Steve Holden writes: >>> Right now, even asking for HTTPS support is too much to ask. Heck, >>> even asking for the fake HTTPS support to be identified as such is too >>> much, apparently. >>> >> No, Paul, nobody will complain if you *ask* ... > > Er, that wasn't me... > Oh sorry, no more it was. >> A question I've been asking myself quite a lot recently is how the PSF >> could, were funding to be available, direct the development of Python in >> specific directions,... > > Crypto in the stdlib is not a matter of funding or (technical) > priorities. It's a policy issue; the maintainers were (at least as of a > few years ago) concerned about legal restrictions on crypto in some > jurisdictions causing problems with distributing Python if it included > crypto. I know that other systems (Java, Mozilla, etc) include crypto > but they may have had to jump through some hoops for that purpose. > There are administrative hoops to jump through still in the US to export cryptographic code. Further, if the standard distribution were to include it then the requirements of the US government do still come into play, and it would be a pain to have to have people downloading the software certify (for example) that they weren't intending to re-export it to a "prohibited" country. We can get around some of these issues by retaining the hosting on mainland Europe rather than in the USA, but these issues do demand careful study which apparently nobody really has time for at present. regards Steve -- Steve Holden +1 571 484 6266 +1 800 494 3119 PyCon is coming! Atlanta, Feb 2010 http://us.pycon.org/ Holden Web LLC http://www.holdenweb.com/ UPCOMING EVENTS:http://holdenweb.eventbrite.com/ -- http://mail.python.org/mailman/listinfo/python-list
Re: lightweight encryption of text file
On Jan 8, 11:14 am, Daniel Fetchinson wrote: > I have a plain text file which I would like to protect in a very > simple minded, yet for my purposes sufficient, way. I'd like to > encrypt/convert it into a binary file in such a way that possession of > a password allows anyone to convert it back into the original text > file while not possessing the password one would only see the > following with the standard linux utility 'file': > > [fetchin...@fetch ~]$ file encrypted.data > encrypted.data: data > > and the effort required to convert the file back to the original text > file without the password would be equivalent to guessing the > password. gpg -c simpletextfile.txt -o simpletextfile.gpg But I guess you can't depend on users to have gpg installed so you have to roll out some unvetted Python tool. Carl Banks -- http://mail.python.org/mailman/listinfo/python-list
Re: lightweight encryption of text file
On Sun, Jan 10, 2010 at 3:26 PM, Paul Rubin wrote: > geremy condra writes: >> Not sure why in the world you would homebrew something like this- a >> small dependency isn't that bad, and aes can be pretty simple to use. >> Might as well go for the industrial strength approach. > > In my experience, 1) small dependencies ARE that bad, since they mean > you have to develop and test on every platform that you want your code > to run on; And having no dependencies frees you from the burden of testing where your software will be deployed? I don't think so. > 2) using a serious library requires quite a bit of knowledge > and decision-making which not everyone is equipped to do. Homebrewing is not a good solution to the problem of being ignorant of modern cryptography. > "AES" is not so simple to use unless you know what you're doing in > terms of modes, nonces, etc. Seems pretty simple to me- use AES 192, don't use ECB mode, and use your library of choice's key strengthening utilities. Even blatantly ignoring that advice would still probably give you better results than homebrewing though, so I don't really see the issue here. > Having supported this kind of package in a commercial > setting in the past, IMO, for the sort of (common) application in > question, it's best to keep things as simple as possible and supply a > single interface that provides encryption, authentication, and random > initialization all in one call. The cost is a little bit of ciphertext > bloat, but it prevents all kinds of security failures frequently > overlooked by novices. > > I'd like it a lot if the Python stdlib could include a serious > cryptography module. That was rejected for regulatory reasons several > years ago, but maybe things are changing enough that the issue can be > revisited sometime. I agree. I inquired about it not too long ago on python-ideas; little serious discussion ensued. Geremy Condra -- http://mail.python.org/mailman/listinfo/python-list
Re: lightweight encryption of text file
Carl Banks wrote: > On Jan 8, 11:14 am, Daniel Fetchinson > wrote: >> I have a plain text file which I would like to protect in a very >> simple minded, yet for my purposes sufficient, way. I'd like to >> encrypt/convert it into a binary file in such a way that possession of >> a password allows anyone to convert it back into the original text >> file while not possessing the password one would only see the >> following with the standard linux utility 'file': >> >> [fetchin...@fetch ~]$ file encrypted.data >> encrypted.data: data >> >> and the effort required to convert the file back to the original text >> file without the password would be equivalent to guessing the >> password. > > > gpg -c simpletextfile.txt -o simpletextfile.gpg > > But I guess you can't depend on users to have gpg installed so you > have to roll out some unvetted Python tool. > > The OP's statement of requirements would be pretty much satisfied by the "crypt" utility. He can even run it under Cygwin on Windows if necessary. Cryptographic sophistication (or even cryptographic security) was not requested (and would not be provided anyway by most of the suggested solutions). If any real protection is required then an ad-hoc program is definitely not the way to provide it. regards Steve -- Steve Holden +1 571 484 6266 +1 800 494 3119 PyCon is coming! Atlanta, Feb 2010 http://us.pycon.org/ Holden Web LLC http://www.holdenweb.com/ UPCOMING EVENTS:http://holdenweb.eventbrite.com/ -- http://mail.python.org/mailman/listinfo/python-list
Re: interactive terminal in Ubuntu Linux : libreadline5-dev works only in Python 2.6 not 3.1
On Jan 10, 8:16 pm, Dave WB3DWE wrote: > On Sat, 9 Jan 2010 16:48:52 -0800 (PST), casevh > wrote: > > >On Jan 9, 3:10 pm, pdlem...@earthlink.net wrote: > >> On Sat, 9 Jan 2010 13:27:07 -0800 (PST), casevh > >> wrote: > > >1) Try the commands again. Make sure all the "./configure" options are > >on one line. Make sure to do "sudo make altinstall". (Don't use "sudo > >make install"; it will give your version of Python the name "python" > >and that can cause confusion on your system.) > > >2) Move your applications to another directory. > > >3) Try running "python3.1" while you are in that directory. > > >If this doesn't work, report back on the error messages you receive. > > Thanks casevh for your time & patience. > The ./configure . . . was a "continuous" line , although it ran over to > next line even on 132 char wide terminal because of names of system & > dir. I was careful with the spaces and hyphens. > In my reply the "make install" was a typo , I did run make altinstall. > > Moved all my code to pycode dir on my home directory. Removed all > files from /usr/local/lib/python3.1/dlmodules and removed that dir. > > Twice ran the recompile : > make distclean > ./configure --prefix=/usr/local --with-computed-gotos > --with-wide-unicode > <^ one space> > make > sudo make altinstall > After each reinstall had same problems : cannot import random or > any code using it, although random.py is in Lib : > Traceback > File "", line 1, in > File "random.py", line 46, in > import collections as _collections > File "collections.py", line 9 in > from _collections import deque, default dict > ImportError: /usr/local/lib/python3.1/lib-dynload/collections.so: > undefined symbol: PyUnicodeUCS4_FromString > > After second reinstall today I also found that a module importing > "time" would not run. Likewise could not import time at >>> . > Same error, ending : undefined symbol: PyUnicode UCS4_FromString > > And my original problem still there : fouled up keys in interactive > terminal. Seems minor now ; ) Should I try to remove everything > and reopen the tarball ? > Dave WB3DWE, central Texas Are you sure you are using the new version of python3.1 (the one located in /usr/local/bin/)? What is the result of "which python3.1"? What happens if you run "/usr/local/bin/python3.1"? casevh -- http://mail.python.org/mailman/listinfo/python-list
how to duplicate array entries
Hi there, I have an array x=[1,2,3] Is there an operator which I can use to get the result [1,1,1,2,2,2,3,3,3] ? I tried x*3, which resulted in [1,2,3,1,2,3,1,2,3] I also tried [[b,b,b] for b in x] which led to [[1,2,3],[1,2,3], [1,2,3]], but this isn't what I want either. Cheers, Sebastian -- http://mail.python.org/mailman/listinfo/python-list
Re: how to duplicate array entries
On Jan 11, 4:21 pm, Sebastian wrote: > I also tried [[b,b,b] for b in x] which led to [[1,2,3],[1,2,3], > [1,2,3]] Sorry, I have to correct myself. The quoted line above resulted in [[1,1,1],[2,2,2],[3,3,3]] of course! Cheers, Sebastian -- http://mail.python.org/mailman/listinfo/python-list
Re: how to duplicate array entries
On Sun, Jan 10, 2010 at 10:21 PM, Sebastian wrote: > Hi there, > > I have an array x=[1,2,3] > > Is there an operator which I can use to get the result > [1,1,1,2,2,2,3,3,3] ? > > I tried x*3, which resulted in [1,2,3,1,2,3,1,2,3] > I also tried [[b,b,b] for b in x] which led to [[1,2,3],[1,2,3], > [1,2,3]], but this isn't what I want either. from itertools import chain, repeat n = 3 stretched = list(chain(*[repeat(item, n) for item in x])) Cheers, Chris -- http://blog.rebertia.com -- http://mail.python.org/mailman/listinfo/python-list
Re: how to duplicate array entries
Sebastian writes: > Hi there, > > I have an array x=[1,2,3] In python such an object is called a "list". (In cpython it's implemented as an automatically resizable array.) > > Is there an operator which I can use to get the result > [1,1,1,2,2,2,3,3,3] ? There's no operator that will give you that directly - but there are plenty of one-liners that will yield that list. e.g: >>> list(itertools.chain(*([x]*3 for x in [1,2,3]))) [1, 1, 1, 2, 2, 2, 3, 3, 3] -- http://mail.python.org/mailman/listinfo/python-list
Re: integer and string compare, is that correct?
On Jan 10, 10:34 am, Nobody wrote: > Hellmut Weber wrote: > >> being a causal python user (who likes the language quite a lot) > >> it took me a while to realize the following: > >> >>> max = '5' > >> >>> n = 5 > >> >>> n >= max > >> False > > >> Section 5.9 Comparison describes this. > > >> Can someone give me examples of use cases > Peter Otten wrote: > > The use cases for an order that works across types like int and str are weak > > to non-existent. Implementing it was considered a mistake and has been fixed > > in Python 3: > 5 > "5" > > Traceback (most recent call last): > > File "", line 1, in > > TypeError: unorderable types: int() > str() > > If you actually need to perform comparisons across types, you can rely > upon the fact that tuple comparisons are non-strict and use e.g.: > > > a = 5 > > b = '5' > > (type(a).__name__, a) < (type(b).__name__, b) > True > > (type(a).__name__, a) > (type(b).__name__, b) > False > > The second elements will only be compared if the first elements are equal > (i.e. the values have the same type). But this method gives you 3.0 < 2 because 'float' < 'int'. Probably not what you want. -- http://mail.python.org/mailman/listinfo/python-list
Re: how to duplicate array entries
Paul Rudin wrote: Sebastian writes: Hi there, I have an array x=[1,2,3] In python such an object is called a "list". (In cpython it's implemented as an automatically resizable array.) Is there an operator which I can use to get the result [1,1,1,2,2,2,3,3,3] ? There's no operator that will give you that directly - but there are plenty of one-liners that will yield that list. e.g: list(itertools.chain(*([x]*3 for x in [1,2,3]))) [1, 1, 1, 2, 2, 2, 3, 3, 3] List comprehension also works nicely for this problem, and may be clearer to some. >>> x = [1,2,3] >>> print [ifor i in xfor k in range(3)] [1, 1, 1, 2, 2, 2, 3, 3, 3] Gary Herron -- http://mail.python.org/mailman/listinfo/python-list
Re: how to duplicate array entries
On Sun, 10 Jan 2010 22:21:54 -0800, Sebastian wrote: > Hi there, > > I have an array x=[1,2,3] You have a list. Python has an array type, but you have to "import array" to use it. > Is there an operator which I can use to get the result > [1,1,1,2,2,2,3,3,3] ? Not an operator, but you can do it easily with a function. Here's the simple version: >>> def duplicate(items, count): ... L = [] ... for item in items: ... L.extend([item]*count) ... return L ... >>> duplicate([1,2,3], 3) [1, 1, 1, 2, 2, 2, 3, 3, 3] Here's a version which is short and simple enough to use in-line, but will be slow for large lists: >>> x = [1,2,3] >>> count = 3 >>> sum([[item]*count for item in x], []) [1, 1, 1, 2, 2, 2, 3, 3, 3] Finally, here's a nasty hack that you should never, ever, ever use for any reason except to win a bet: >>> [locals()['_[1]'].extend([item]*(count-1)) or item for item in x] [1, 1, 1, 2, 2, 2, 3, 3, 3] -- Steven -- http://mail.python.org/mailman/listinfo/python-list
Re: "Advanced" Python programming book?
On Jan 10, 2:35 pm, flow wrote: > I've just finished reading a sort of beginner Python book, and I know > quite a bit now but I'm looking for a book that can teach me advanced > aspects of Python - code optimisation, threading, etc. > > Any recommendations? > > Cheers. I like to add this one, which is nice to read just after reading the "starters", covers all kinds of topics, and written by someone who knows Python (I think at least). http://oreilly.com/catalog/9780596009250/ HTH, Marco -- http://mail.python.org/mailman/listinfo/python-list
Re: class viewer ?
Stef Mientki writes: > from the given class, it's ancestors and it's derived classes, > I'ld like to get the following information in a tree like structure: > > - the file were the class is definied > - the attributes, split in inherited / created / overriden > - the methodes, split in inherited / created / overriden > - the files were instances of the class are created > - and probably I forget a few > > any suggestions ? The “Emacs Code Browser” http://ecb.sourceforge.net/> was seemingly designed for languages like C++ and Java, but it serves well enough for Python also. I find it annoying to use, since it seems to assume mouse navigation and has rather impenetrable (for me) documentation. But it does seem to do much of what you're asking for, and a big plus is that it's not specific to Python. -- \ “The most common way people give up their power is by thinking | `\ they don't have any.” —Alice Walker | _o__) | Ben Finney -- http://mail.python.org/mailman/listinfo/python-list
