🌐 Mailman 3 July 2010 - Python-list - python.org

Performance ordered dictionary vs normal dictionary
by Navkirat Singh July 29, 2010

July 29, 2010

Hi guys, I was wondering what would be better to do some medium to heavy book keeping in memory - Ordered Dictionary or a plain simple Dictionary object?? Regards, N4v

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Newbie question regarding SSL and certificate verification
by geremy condra July 29, 2010

July 29, 2010

On Wed, Jul 28, 2010 at 4:41 PM, Jeffrey Gaynor <jgaynor(a)ncsa.uiuc.edu> wrote: > Hi, > > I am making a first large project in python and am having quite a bit of difficulty unscrambling various python versions and what they can/cannot do. To wit, I must communicate with certain services via https and am required to perform certificate verification on them. > > The problem is that I also have to do this under CentOS 5.5 which only uses python 2.4 as its default -- this is not negotiable. As near as I can tell from reading various posts, the https client does not do verification and there is no low-level SSL support to provide a workaround. Near as I can tell from reading, 2.6 does include this. Am I getting this right? Is there a simple way to do this? More to the point, I need to know pretty darn quick if this is impossible so we can try and plan for it. > > So the quick question: Has anyone done certificate verification using 2.4 and if so, how? > > Thanks! M2Crypto is the way to go here. I think there's an example on their site. Geremy Condra

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Newbie question regarding SSL and certificate verification
by Jeffrey Gaynor July 28, 2010

July 28, 2010

Hi, I am making a first large project in python and am having quite a bit of difficulty unscrambling various python versions and what they can/cannot do. To wit, I must communicate with certain services via https and am required to perform certificate verification on them. The problem is that I also have to do this under CentOS 5.5 which only uses python 2.4 as its default -- this is not negotiable. As near as I can tell from reading various posts, the https client does not do verification and there is no low-level SSL support to provide a workaround. Near as I can tell from reading, 2.6 does include this. Am I getting this right? Is there a simple way to do this? More to the point, I need to know pretty darn quick if this is impossible so we can try and plan for it. So the quick question: Has anyone done certificate verification using 2.4 and if so, how? Thanks!

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Re: Ascii to Unicode.
by John Machin July 28, 2010

July 28, 2010

On Jul 29, 4:32 am, "Joe Goldthwaite" <j...(a)goldthwaites.com> wrote: > Hi, > > I've got an Ascii file with some latin characters. Specifically \xe1 and > \xfc. I'm trying to import it into a Postgresql database that's running in > Unicode mode. The Unicode converter chokes on those two characters. > > I could just manually replace those to characters with something valid but > if any other invalid characters show up in later versions of the file, I'd > like to handle them correctly. > > I've been playing with the Unicode stuff and I found out that I could > convert both those characters correctly using the latin1 encoder like this; > > import unicodedata > > s = '\xe1\xfc' > print unicode(s,'latin1') > > The above works. When I try to convert my file however, I still get an > error; > > import unicodedata > > input = file('ascii.csv', 'r') > output = file('unicode.csv','w') > > for line in input.xreadlines(): > output.write(unicode(line,'latin1')) > > input.close() > output.close() > > Traceback (most recent call last): > File "C:\Users\jgold\CloudmartFiles\UnicodeTest.py", line 10, in __main__ > output.write(unicode(line,'latin1')) > UnicodeEncodeError: 'ascii' codec can't encode character u'\xe1' in position > 295: ordinal not in range(128) > > I'm stuck using Python 2.4.4 which may be handling the strings differently > depending on if they're in the program or coming from the file. I just > haven't been able to figure out how to get the Unicode conversion working > from the file data. > > Can anyone explain what is going on? Hello hello ... you are running on Windows; the likelihood that you actually have data encoded in latin1 is very very small. Follow MRAB's answer but replace "latin1" by "cp1252".

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Ascii to Unicode.
by Joe Goldthwaite July 28, 2010

July 28, 2010

Thanks to all of you who responded. I guess I was working from the wrong premise. I was thinking that a file could write any kind of data and that once I had my Unicode string, I could just write it out with a standard file.write() operation. What is actually happening is the file.write() operation was generating the error until I re-encoded the string as utf-8. This is what worked; import unicodedata input = file('ascii.csv', 'rb') output = file('unicode.csv','wb') for line in input.xreadlines(): unicodestring = unicode(line, 'latin1') output.write(unicodestring.encode('utf-8')) # This second encode is what I was missing. input.close() output.close() A number of you pointed out what I was doing wrong but I couldn't understand it until I realized that the write operation didn't work until it was using a properly encoded Unicode string. I thought I was getting the error on the initial latin Unicode conversion not in the write operation. This still seems odd to me. I would have thought that the unicode function would return a properly encoded byte stream that could then simply be written to disk. Instead it seems like you have to re-encode the byte stream to some kind of escaped Ascii before it can be written back out. Thanks to all of you who took the time to respond. I really do appreciate it. I think with my mental block, I couldn't have figure it out without your help.

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Re: python terminology on classes
by Bruno Desthuilliers July 28, 2010

July 28, 2010

Peng Yu a écrit : > Hi > > I'm still kind of confused about the terminology on classes in python. > > Could you please let me know what the equivalent terms for the > following C++ terms? C++ and Python having very different semantics and object models, there's not necessarily a straight one to one mapping. > > constructor Python uses a smalltalk-like 2 phases instanciation / initialisation scheme. First the "proper" construction (__new__) is called with the class object as first argument, and it must return an unintialised instance of the class. Then the initialiser (__init__) is called on this instance. Now one usually only implements the initialiser, as the default object.__new__ method does what you would expect, so you'll often see people qualifying __init__ as the constructor. > destructor Python has no real destructor. You can implement a __del__ method that will _eventually_ be called before the instance gets garbage-collected, but you'd rather not rely on it. Also, implementing this method will prevent cycle detection. > member function => method. Note that Python's "methods" are really thin wrappers around function objects that are attributes of the class object. You'll find more on this here: http://wiki.python.org/moin/FromFunctionToMethod > member variable => Attribute > virtual member function All Python's methods are virtual. > function => function !-) Note that in Python, functions and classes are objects. > I think that C++ "function" is equivalent to python "function" and C++ > "member function" is equivalent to python "method". But I couldn't > locate where the original definitions of the corresponding python > terms in the manual as these term appear many times. Could you please > point me where to look for the definition of these python > corresponding terms? You just cannot directly translate C++ into Python, and while there are similarities trying to write C++ in Python will not get you very far.

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Re: Ascii to Unicode.
by John Nagle July 28, 2010

July 28, 2010

On 7/28/2010 11:32 AM, Joe Goldthwaite wrote: > Hi, > > I've got an Ascii file with some latin characters. Specifically \xe1 and > \xfc. I'm trying to import it into a Postgresql database that's running in > Unicode mode. The Unicode converter chokes on those two characters. > > I could just manually replace those to characters with something valid but > if any other invalid characters show up in later versions of the file, I'd > like to handle them correctly. > > > I've been playing with the Unicode stuff and I found out that I could > convert both those characters correctly using the latin1 encoder like this; > > > import unicodedata > > s = '\xe1\xfc' > print unicode(s,'latin1') > > > The above works. When I try to convert my file however, I still get an > error; > > import unicodedata > > input = file('ascii.csv', 'r') > output = file('unicode.csv','w') > > for line in input.xreadlines(): > output.write(unicode(line,'latin1')) > > input.close() > output.close() > Try this, which will get you a UTF-8 file, the usual standard for Unicode in a file. for rawline in input : unicodeline = unicode(line,'latin1') # Latin-1 to Unicode output.write(unicodeline.encode('utf-8')) # Unicode to as UTF-8 John Nagle

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Ascii to Unicode.
by Joe Goldthwaite July 28, 2010

July 28, 2010

Hi, I've got an Ascii file with some latin characters. Specifically \xe1 and \xfc. I'm trying to import it into a Postgresql database that's running in Unicode mode. The Unicode converter chokes on those two characters. I could just manually replace those to characters with something valid but if any other invalid characters show up in later versions of the file, I'd like to handle them correctly. I've been playing with the Unicode stuff and I found out that I could convert both those characters correctly using the latin1 encoder like this; import unicodedata s = '\xe1\xfc' print unicode(s,'latin1') The above works. When I try to convert my file however, I still get an error; import unicodedata input = file('ascii.csv', 'r') output = file('unicode.csv','w') for line in input.xreadlines(): output.write(unicode(line,'latin1')) input.close() output.close() Traceback (most recent call last): File "C:\Users\jgold\CloudmartFiles\UnicodeTest.py", line 10, in __main__ output.write(unicode(line,'latin1')) UnicodeEncodeError: 'ascii' codec can't encode character u'\xe1' in position 295: ordinal not in range(128) I'm stuck using Python 2.4.4 which may be handling the strings differently depending on if they're in the program or coming from the file. I just haven't been able to figure out how to get the Unicode conversion working from the file data. Can anyone explain what is going on?

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Re: Why is there no platform independent way of clearing a terminal?
by Jonathan Hartley July 28, 2010

July 28, 2010

On Jul 28, 5:47 pm, Thomas Jollans <tho...(a)jollans.com> wrote: > On 07/28/2010 06:01 PM, Jonathan Hartley wrote: > > > > > Oh, plus, while we're on this subject: > > > Am I right that curses in Python stdlib doesn't work on Windows, and > > there is currently no simple way to fix this? > > > Also, is it crazy to imagine that if colorama was pushed through to > > completion (ie. to support a majority of the relevant ANSI codes) then > > Python's stdlib curses module, unmodified, would suddenly just work on > > Windows? (after a call to 'colorama.init()') > > > I presume these ideas are oversimplifications or just plain wrong. If > > anyone would care to correct my misunderstandings, I'd be very > > grateful. > > Correct: it's not THAT simple. > > Python's curses module is a (I'm not sure how thin) wrapper around the > good old UNIX curses (ncurses, ...) library. This is written in C, not > Python, so it doesn't use Python's sys.stdout object to do I/O. > > I haven't had a look at colorama, but it sounds like it hooks into > sys.stdout, or Python file objects anyway. Far, far above the layer > curses does I/O on. So, if you ported a normal curses library to > Windows, colorama wouldn't help you a bit. > > It might be possible to write a curses-compatible library that works > with cmd.exe. Maybe. But, even if it's possible, I don't think it's > easy, and I especially don't think it would be particularly rewarding. > > Also, I just stumbled uponhttp://adamv.com/dev/python/curses/-- this > is probably the only reasonable way to get a useful curses API on > Windows: forget the DOS box. > ncurses ... is written in C, not > Python, so it doesn't use Python's sys.stdout object to do I/O. Ah, I should have spotted that. Of course. Thanks for the enlightenment. And Neil Cerutti, I think I'll just email the whole source tree to myself, and have a script that scans my inbox, unzips source trees and runs their tests. Much nicer. :-)

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Re: urllib timeout
by kBob July 28, 2010

July 28, 2010

On Jul 27, 4:56 pm, MRAB <pyt...(a)mrabarnett.plus.com> wrote: > kBob wrote: > > On Jul 27, 4:23 pm, MRAB <pyt...(a)mrabarnett.plus.com> wrote: > >> kBob wrote: > > >>> I created a script to access weather satellite imagery fron NOAA's > >>> ADDS. > >>> It worked fine until recently with Python 2.6. > >>> The company changed the Internet LAN connections to "Accept Automatic > >>> settings" and "Use automatic configuration script" > >>> How do you get urllib.urlopen to use the the "automatic script" > >>> configuration? > >>> This code worked recently, until the company implemented these LAN > >>> connections... > >>> SAT_URL = "http://adds.aviationweather.gov/data/satellite/ > >>> latest_BWI_vis.jpg" > >>> satpic = urllib.urlopen(SAT_URL, proxies=0 ) > >>> satimg = satpic.read() > >> For the record, I got: > > >> >>> import urllib > >> >>> SAT_URL = > >> "http://adds.aviationweather.gov/data/satellite/latest_BWI_vis.jpg" > >> >>> satpic = urllib.urlopen(SAT_URL, proxies=0 ) > >> Traceback (most recent call last): > >> File "<stdin>", line 1, in <module> > >> File "C:\Python26\lib\urllib.py", line 79, in urlopen > >> opener = FancyURLopener(proxies=proxies) > >> File "C:\Python26\lib\urllib.py", line 617, in __init__ > >> URLopener.__init__(self, *args, **kwargs) > >> File "C:\Python26\lib\urllib.py", line 129, in __init__ > >> assert hasattr(proxies, 'has_key'), "proxies must be a mapping" > >> AssertionError: proxies must be a mapping > > >> However, urllib.urlretrieve(...) works.- Hide quoted text - > > >> - Show quoted text - > > > I saw that, but I still get the same error time out error ... > > >>>> import urllib > >>>> SAT_URL = "http://adds.aviationweather.gov/data/satellite/" > >>>> SAT_FILE = "latest_BWI_vis.jpg" > >>>> satimg = urllib.urlretrieve( SAT_URL, SAT_FILE ) > > Traceback (most recent call last): > > File "<stdin>", line 1, in <module> > > File "c:\python26\lib\urllib.py", line 93, in urlretrieve > > return _urlopener.retrieve(url, filename, reporthook, data) > > File "c:\python26\lib\urllib.py", line 237, in retrieve > > fp = self.open(url, data) > > File "c:\python26\lib\urllib.py", line 205, in open > > return getattr(self, name)(url) > > File "c:\python26\lib\urllib.py", line 344, in open_http > > h.endheaders() > > File "c:\python26\lib\httplib.py", line 904, in endheaders > > self._send_output() > > File "c:\python26\lib\httplib.py", line 776, in _send_output > > self.send(msg) > > File "c:\python26\lib\httplib.py", line 735, in send > > self.connect() > > File "c:\python26\lib\httplib.py", line 716, in connect > > self.timeout) > > File "c:\python26\lib\socket.py", line 514, in create_connection > > raise error, msg > > IOError: [Errno socket error] [Errno 10060] A connection attempt > > failed because > > the connected party did not properly respond after a period of time, > > or establis > > hed connection failed because connected host has failed to respond > > It should be like this: > > SAT_URL = > "http://adds.aviationweather.gov/data/satellite/latest_BWI_vis.jpg" > SAT_FILE = r"C:\latest_BWI_vis.jpg" > urllib.urlretrieve(SAT_URL, SAT_FILE)- Hide quoted text - > > - Show quoted text - It doesn't matter, the same error 10060 appears . The connection problem has to do with the proxy settings. In order for me to use Internet Explorer, the LAN's Automatic configuration must be turned on and use a script found on the company's proxy server. I was wondering how to get urllib.urlopen to access the script on the proxy server. Thanks for your help. Kelly

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