Re: [Tutor] OT: need computer advice from wise Tutors
On Sat, Jun 26, 2010 at 4:46 PM, Steven D'Aprano wrote: > Apart from: > The OP was asking about upgrading from Vista to 7, so let me answer your objections here... having no default email client (what sort of two-bit operating system > doesn't have an email client in 2010?); > Jesus, you _miss_ Outlook Express? Seriously: the new default is webmail. Like it, don't like it, but it's really not as if you can't get your mail. > the automatic upgrades that run silently in the background with no easy > way to turn them on or off Just like XP and Vista, you're asked during installation whether you want to allow or disallow automatic updates. If you breeze past that question, then - just like in XP and Vista - you can right-click on the little icon that appears in your system tray (oops, I mean "notification area.") True, Windows 7 is proactive about hiding stuff in the tray... but it does still appear there. A more legitimate gripe is that, after downloading those updates, Windows insists on applying them when you shut down the computer. If you're in a hurry, that can be a PITA. > (always fun when your Internet download cap > is completely used up TWO DAYS into the month -- especially when you > don't know because you can't read the email from your ISP due to not > having an email client, To paraphrase, "what sort of two-bit ISP doesn't have a webmail site in 2010?" the gratuitous UI changes (am I missing something, or does Internet > Explorer no longer have a menubar?); > That's IE, not Windows. Windows 7 comes with IE 8; Vista came with IE 7; XP came with IE 6. I don't care for the look myself, but then I never use IE if I can avoid it (Firefox for mail and searching, 'cause I love me some plugins; Chrome for everything else, 'cause it's fast as hell. IE when I'm on a client machine and there's nothing better.) IE 8 is being rolled out to all versions of Windows in any case, so that's not a reason not to upgrade - unless you were planning to turn off Windows Update in Vista, which is a bad idea for security reasons... the use of third-party applications like Adobe Acrobat Reader which have > become overloaded with *stupid* security vulnerabilities *by design* > (years after Microsoft themselves got burnt, time and time again, by > allowing the web-browser and mail client to execute random code found > on the internet, somebody at Adobe apparently thought it would be a > good idea for the PDF reader to do the same thing *facepalms*); and > Microsoft doesn't provide a PDF reader of its own - I'm not sure, but I suspect that's for legal reasons - so whatever PDF reader you use, it HAS to be third-party. Why Adobe? Probably because it's called "_Adobe_ Acrobat?" Now, I hate Adobe products for the same reasons you mentioned, so I use and recommend the free Foxit Reader (www.foxitsoftware.com). But that was the same under XP and Vista. > consequently the proliferation of adware and spyware (even > the "legitimate" anti-malware companies fill your browser with ad-laden > toolbars and try terrifying the user with "your computer is > unprotected" warnings -- no wonder the average user can't tell the > difference between legitimate anti-malware and trojan horses). > Again, not new in 7 - and, as a matter of fact, possibly somewhat better than in Vista. > On the other hand, it is quite pretty. > Screw pretty. Pretty don't pay the rent. First thing I do on any machine I get my hands on is turn off the $%^&* Aero Glass - why would I take that kind of performance hit for the dubious pleasure of a translucent titlebar? But guess what? MS introduced that piece of idiotism in - wait for it - Vista. My reasons FOR upgrading: - Better UAC. UAC is never going to feel natural to users (like me - I freely admit it) who came up from DOS, and are stuck in a single-user mindset. Users raised on *nixes, on the other hand, find UAC to be a laughable baby step on the way to a real least-privilege security model. That said, 7 does a much more natural job (than Vista) of asking for elevation only when needed, and staying out of the way most of the rest of the time. - Faster sleep/hibernation and wakeup. I have no idea what they did under the covers, but on my laptop under Vista 64-bit, it took a minute or so to hibernate, and 30 seconds or so to wake up. 7 takes 30 seconds or so to hibernate, and 15 seconds to wake up. Not astronomical, but coupled with the next point, it's HUGE. - Better wireless networking. Coming out of sleep or hibernation, it used to take up to a minute and a half to connect to a known wireless network (in other words, a network I'd previously connected to and saved settings for.) Now, I'm generally connected even before I can see the desktop - 3 to 5 seconds, maybe. I carry my laptop everywhere, and connect to wireless networks at my clients (and Starbucks!) all day long, so this is a MAJOR deal for me. - Seriously improved multi-monitor support. I've loved using dual m
Re: [Tutor] Advice on math
>> Hello, I've enjoying learning python for the first few years, and >> appreciate all the help I have received from this list. I had some >> interest in programming and am very glad to have made python my choice >> of programming language. Since I didn't go to college for computer >> studies, I feel my math is kind of rusty in some areas, and looks like >> improving/regaining math skills would help a lot in programming, >> logic, algorithms, etc. >> Right now I think I need a better understanding of logarithm, arrays >> (matrixes), and even probability. What links would you all recommend >> that would be useful for me to learn these things in a newbie-friendly >> way? >> >> >> > If you want to code+learn, nothing beats ProjectEuler ( > http://projecteuler.net/ ). However I assume you have basic understanding of > maths. Not to hijack the thread, but that's awesome! Only when you solve the problems and then read the forum thread, do you realize how crude your own solutions are, compared to some very clever fellows. Far better than a crossword to keep things stimulated. -Modulok- ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] class questions
On Sun, Jun 27, 2010 at 2:09 AM, Steven D'Aprano wrote: > On Sun, 27 Jun 2010 03:05:16 am Payal wrote: >> >> Can you give any simple example where this simple mro will work >> incorrectly? > > Probably not... it's quite complicated, which is why it's rare. I'll > have a think about it and see what I can come up with. > Here's my attempt. Consider this simple Diamond hierarchy: class A: def x(self): return "in A" class B(A): pass class C(A): def x(self): return "in C" class D(B, C): pass A / \ / \ B C \/ \ / D Now, with this diagram the following code probably doesn't do what you expect: >>> obj = D() >>> obj.x() 'in A' D inherits from C, which overrides the x method. But this is seemingly completely ignored by python, which produces the A.x method! So why does this happen? well, the old MRO uses a simple depth-first, left-to-right search. This means that to find a method, python first looks into the leftmost parent, then its leftmost parent, et cetera et cetera. For our diamond, that means this MRO: D, B, A, C, A so, when you try to access D.x, it will look first in D (not found), B (not found), then A, producing the A.x method. And this probably isn't what you want (we inherited from C for a reason, you know). For new style classes, the MRO is actually D, B, C, A. That produces the correct results. The algorithm is a little complicated, and if you would like to know, the link you posted earlier has all the details. Hugo ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] class questions
Hi Hugo, On Sun, Jun 27, 2010 at 01:27:37PM +0200, Hugo Arts wrote: > Here's my attempt. Consider this simple Diamond hierarchy: [...] > Now, with this diagram the following code probably doesn't do what you expect: Actually, it does what is expected. The old mro specifically says, bottom-top, left-right. So we expected D-B-A-C-A. Steven says in some cases even this simple logic of bottom-top, left-right search will not work. As he says, a simple example of it failing is diffclt to write, so meanwhile I will take his word for it. Thanks for the help. With warm regards, -Payal -- ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] class questions
Hi Steven, Thanks a lot for patiently explaining the concepts. I uderstood most of it. With warm regards, -Payal -- On Sun, Jun 27, 2010 at 10:09:38AM +1000, Steven D'Aprano wrote: > Probably not... it's quite complicated, which is why it's rare. I'll > have a think about it and see what I can come up with. ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] OT: need computer advice from wise Tutors
"Steven D'Aprano" wrote having no default email client (what sort of two-bit operating system doesn't have an email client in 2010?); To be fair to MS - and it pains me to do so - they have been beat up so much by the lawyers that its hardlly surprising. After all they have been forced to remove the browser from the OS in Europe (and elsewhere?). Why not the email client too? After all, Linux doesn't tecchnically have a mail client (unless you count command line mail), it's the distros that add that. the automatic upgrades that run silently in the background with no easy way to turn them on or off Yes I really hate that! the gratuitous UI changes (am I missing something, or does Internet Explorer no longer have a menubar?); None of the new MS applications do, the menu bar has been merged into the new look toolbar. Thus making something small and unobtrusive large and extremely obtrusive and requiring a relearning of the whole command structure! I really don't like the new MS UI thing, even after 6 montrhs of use it still drives me nuts! (I use Win7 on my laptop at work) the use of third-party applications like Adobe Acrobat Reader which have become overloaded with *stupid* security vulnerabilities *by design* But that applies to all OS that Reader runs on doesn't it? Can't blame Windows 7 for that. consequently the proliferation of adware and spyware (even Yep, agree with this too. On the other hand, it is quite pretty. Hmm, I'm stlll not sure about that... But then, I srtill run Windows XP in Classic mode with Windows95 style menu and start button etc. Alan G. ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] class questions
Thanks a lot Eike for the code snippet. I got the idea now. With warm regards, -Payal -- On Sat, Jun 26, 2010 at 10:41:59PM +0200, Eike Welk wrote: > Hello Payal! > > On Saturday June 26 2010 19:05:16 Payal wrote: > > Can we say that our own exception classes have only maybe a doc-string > > and pass, nothing more? > > No, you let the exception transport the information that you need for > handling > the error. This is an exception that I use to transport user visible error > messages in a compiler, that I write as a hobby: > > > class UserException(Exception): > '''Exception that transports user visible error messages.''' > def __init__(self, message, loc=None, errno=None): > Exception.__init__(self) > self.msg = message > self.loc = loc > self.errno = errno > > def __str__(self): > if self.errno is None: > num_str = '' > else: > num_str = '(#%s) ' % str(self.errno) > return 'Error! ' + num_str + self.msg + '\n' + str(self.loc) + '\n' > > def __repr__(self): > return self.__class__.__name__ + str((self.msg, self.loc, > self.errno)) > > It contains: > self.msg : The error message > self.loc : An object encoding the location of the error in the program's >text. Together with the file name and the text. > self.errno : An integer to identify the error, for the test framework. > > That said; the expression's type and the error message are often sufficient > to > handle the error. > > > Eike. ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] OT: need computer advice from wise Tutors
"Marc Tompkins" wrote having no default email client (what sort of two-bit operating system doesn't have an email client in 2010?); Jesus, you _miss_ Outlook Express? Seriously: the new default is webmail. Like it, don't like it, but it's really not as if you can't get your mail. I will miss OE. I actually quite like it, its simple but has all the bits I need for both email and newrgroups. I tried thunderbird and use it on my Linux box but on windows I usually revert to OE. And its lots better than webmail which is only useful for occasional browsing. But I get around 200 plus emails a day (and sometimes the same again in news messages) and trying to manage that on webmail is a nightmare - and you can't read it while offline. I really need an offline mail client. Just like XP and Vista, you're asked during installation whether you want to allow or disallow automatic updates. If you breeze past that question, then - just like in XP and Vista - you can right-click on the little icon that appears in your system tray (oops, I mean "notification area.") OOh. I've never noticed the icon - what does it look like? I didn't do the install so had no say in the decision for work, but for my home PC I'd much rather decide if/when I do "upgrades" - I've had too mamy Windows upgrades kill my PC to the point of needing rebuiilds! To paraphrase, "what sort of two-bit ISP doesn't have a webmail site in 2010?" But webmail is no good if you've used up your bandwidth. A background client might just have received the warning before the quota went bang... - Better wireless networking. Coming out of sleep or hibernation, it used to take up to a minute and a half to connect to a known wireless network I'll need to check that - I've just gotten used to going for a coffee when I boot up - it usually takes me around 5 minutes for everything to get started so I've never noticed the WiFi changes. - Seriously improved multi-monitor support. I've loved using dual monitors I only user this when doing powerpoint presentations but I'll need to take a closer look. Thanks for sharing your comments, even if this thread is seriously off topic! Alan G. ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] socket
"Christopher King" wrote process. In other words, I want to connect two computers. I've looked up socket but the explanations are too complex. I think I need a 2-way conversation with a expert to understand it. Or even better, point me to a easier module. You can read the networking topic in my tutorial;(V2 only) and see a simple explanation with examples. It might be helpful to read the previous two topics as well as a general background to communicating between processes. -- Alan Gauld Author of the Learn to Program web site http://www.alan-g.me.uk/ ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
[Tutor] retrieve URLs and text from web pages
Hi,
I’m new to programming. I’m currently learning python to write a web crawler to
extract all text from a web page, in addition to, crawling to further URLs and
collecting the text there. The idea is to place all the extracted text in a
.txt file with each word in a single line. So the text has to be tokenized. All
punctuation marks, duplicate words and non-stop words have to be removed.
The program should crawl the web to a certain depth and collect the URLs and
text from each depth (level). I decided to choose a depth of 3. I divided the
code to two parts. Part one to collect the URLs and part two to extract the
text. Here is my problem:
1. The program is extremely slow.
2. I'm not sure if it functions properly.
3. Is there a better way to extract text?
4. Are there any available modules to help clean the text i.e. removing
duplicates, non-stop words ...
5. Any suggestions or feedback is appreciated.
(Please Note: the majority of the code (the first part) is written by “James
Mills”. I found the code online and it looks helpful so I used it. I just
modified it and added my code to it)
Thanks,
Kal
import sys
import urllib2
import urlparse
from BeautifulSoup import BeautifulSoup,NavigableString
__version__ = "0.1"
__copyright__ = "CopyRight (C) 2008 by James Mills"
__license__ = "GPL"
__author__ = "James Mills"
__author_email__ = "James Mills, James dot Mills st dotred dot com dot au"
USAGE = "%prog [options] "
VERSION = "%prog v" + __version__
AGENT = "%s/%s" % (__name__, __version__)
def encodeHTML(s=""):
"""encodeHTML(s) -> str
Encode HTML special characters from their ASCII form to
HTML entities.
"""
return s.replace("&", "&") \
.replace("<", "<") \
.replace(">", ">") \
.replace("\"", """) \
.replace("'", "'") \
.replace("--", "&mdash")
class Fetcher(object):
def __init__(self, url):
self.url = url
self.urls = []
def __contains__(self, x):
return x in self.urls
def __getitem__(self, x):
return self.urls[x]
def _addHeaders(self, request):
request.add_header("User-Agent", AGENT)
def open(self):
url = self.url
#print "\nFollowing %s" % url
try:
request = urllib2.Request(url)
handle = urllib2.build_opener()
except IOError:
return None
return (request, handle)
def fetch(self):
request, handle = self.open()
self._addHeaders(request)
if handle:
soup = BeautifulSoup()
try:
content = unicode(handle.open(request).read(), errors="ignore")
soup.feed(content)
#soup = BeautifulSoup(content)
tags = soup('a')
except urllib2.HTTPError, error:
if error.code == 404:
print >> sys.stderr, "ERROR: %s -> %s" % (error, error.url)
else:
print >> sys.stderr, "ERROR: %s" % error
tags = []
except urllib2.URLError, error:
print >> sys.stderr, "ERROR: %s" % error
tags = []
for tag in tags:
try:
href = tag["href"]
if href is not None:
url = urlparse.urljoin(self.url, encodeHTML(href))
if url not in self:
#print " Found: %s" % url
self.urls.append(url)
except KeyError:
pass
# I created 3 lists (root, level2 and level3). #
# Each list saves the URLs of that level i.e. depth. I choose to create 3 #
# lists so I can have the flexibility of testing the text in each level. Also, #
# the 3 lists can be easily combined into one list. #
# Level1:
root = Fetcher('http://www.wantasimplewebsite.co.uk/index.html')
root.fetch()
for url in root:
if url not in root: # Avoid duplicate links
root.append(url)
print "\nRoot URLs are:"
for i, url in enumerate(root):
print "%d. %s" % (i+1, url)
# Level2:
level2 = []
for url in root: # Traverse every element(i.e URL) in root and fetch the URLs
from it
temp = Fetcher(url)
temp.fetch()
for url in temp:
if url not in level2: # Avoid duplicate links
level2.append(url)
print "\nLevel2 URLs are:"
for i, url in enumerate(level2):
print "%d. %s" % (i+1, url)
# Level3:
level3 = []
for url in level2: # Traverse every element(i.e URL) in level2 and fetch the
URLs from it
temp = Fetcher(url)
temp.fetch()
for url in temp:
if url not in level3: # Avoid duplicate links
leve
Re: [Tutor] class questions
On Sun, Jun 27, 2010 at 4:13 PM, Payal wrote: > Hi Hugo, > > On Sun, Jun 27, 2010 at 01:27:37PM +0200, Hugo Arts wrote: >> Here's my attempt. Consider this simple Diamond hierarchy: > [...] >> Now, with this diagram the following code probably doesn't do what you >> expect: > > Actually, it does what is expected. The old mro specifically says, > bottom-top, left-right. So we expected D-B-A-C-A. > Steven says in some cases even this simple logic of bottom-top, > left-right search will not work. As he says, a simple example of it > failing is diffclt to write, so meanwhile I will take his word for it. > The problem of the MRO isn't that it doesn't work, it's that it causes behavior that is unintuitive. In my example, We would expect D.x to be equal to C.x (since D inherits from C, and C overrides the x method). However, this is not the case. This is what the problem is with the old MRO system, not so much that it doesn't work at all, but the results aren't consistent with what you'd expect from multiple inheritance. I just found this link, where Guido explains why he changed the MRO system for new-style classes. He uses the same example I do. http://www.python.org/download/releases/2.2.2/descrintro/#mro Hugo ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
[Tutor] capturing error msg in exception
Hi, Again a few queries regarding exceptions, a. What is the difference between, except ZeroDivisionError as e: print 'Msg : ' , e except ZeroDivisionError ,e: print 'Msg : ' , e Both show, Msg : integer division or modulo by zero b. What is portable and correct way of writing, except (NameError, ZeroDivisionError) as e: print 'Msg : ' , e c. What is the correct Python of writing, except as e: print 'Msg : ' , e# Capturing all exceptions Thanks a lot for the help in advance. With warm regards, -Payal -- p.s. I am always confused where does one put the "?" when I am framing the questions like I have done above (a, b and c)? This is completely OT query for native english speaking people :-) ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] class questions
> The problem of the MRO isn't that it doesn't work, it's that it causes > behavior that is unintuitive. In my example, We would expect D.x to be > equal to C.x (since D inherits from C, and C overrides the x method). > However, this is not the case. This is what the problem is with the > old MRO system, not so much that it doesn't work at all, but the > results aren't consistent with what you'd expect from multiple > inheritance. > > I tried your example in python2.6 >>> class A: ...def x(self): return "in A" ... >>> class B(A): pass ... >>> class C(A): ...def x(self): return "in C" ... >>> class D(B, C): pass ... >>> o = D() >>> o.x() 'in A' If MRO was in python2.3, the output of o.x() should be 'in C'. It works fine on 3.2alpha though. > I just found this link, where Guido explains why he changed the MRO > system for new-style classes. He uses the same example I do. > > http://www.python.org/download/releases/2.2.2/descrintro/#mro > > This was the only useful link I found upon googling. Thanks for your effort though. ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
[Tutor] statements vs. expression and types
Hello, Please forgive for such a silly questions. I have never taken a course on computers so am rough with some of basic technical terminology. a. I read in a book that "lambdas are expressions ... so they can go where functions are not allowed". What are expressions and what are statements? A simple example of both in Python will suffice. b. I read on web that Python has in new releases done "unifications of types and classes". I know what classes are, what are types in simple language. Again please excuse for simple questions and thanks a lot in advance. With warm regards, -Payal -- ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] OT: need computer advice from wise Tutors
On Sun, Jun 27, 2010 at 07:41, Alan Gauld wrote: > "Marc Tompkins" wrote > I will miss OE. I actually quite like it, its simple but has all the bits > I need for both email and newrgroups. I tried thunderbird and use it > on my Linux box but on windows I usually revert to OE. > > And its lots better than webmail which is only useful for occasional > browsing. But I get around 200 plus emails a day (and sometimes the > same again in news messages) and trying to manage that on webmail > is a nightmare - and you can't read it while offline. I really need an > offline mail client. I get 200-300 emails per weekday, and Gmail handles them with aplomb. I have over 300 labels (it's now, finally, possible to nest them). (Tip: use [(From:address) OR (From:me AND ((To: OR Cc:)address))] -- delete the square brackets -- in the "Has the words" textbox when making a filter that will apply to all mail from yourself to: or cc'd to an address OR from an address). Labels can be nested and color coded. Be sure to check out the numerous other features, including the ones on the "Labs" tab. BTW I used Eudora for a decade, and also OE because I had to teach it to my wife. A "feature" very important to me is that with Gmail, my mail is just always THERE, with no need to download it -- and often INSTANTLY there because there are so many other Gmail users. I'll stop my praise of Gmail here because this is an OT of an OT thread :) . Dick ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] capturing error msg in exception
On 27 June 2010 17:47, Payal wrote: > Hi, > Again a few queries regarding exceptions, > > a. What is the difference between, > > except ZeroDivisionError as e: print 'Msg : ' , e > except ZeroDivisionError ,e: print 'Msg : ' , e > > Both show, > Msg : integer division or modulo by zero > > b. What is portable and correct way of writing, > > except (NameError, ZeroDivisionError) as e: print 'Msg : ' , e > > c. What is the correct Python of writing, > except as e: print 'Msg : ' , e# Capturing all exceptions > > Thanks a lot for the help in advance. > With warm regards, > -Payal > -- > > p.s. I am always confused where does one put the "?" when I am framing the > questions like I have done above (a, b and c)? > This is completely OT query for native english speaking people :-) > > I think the 'as' syntax is only available in Python 3.x Question marks go at the end of the sentence where you would normally put a full stop if it wasn't a question. ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] capturing error msg in exception
On 27-Jun-10 10:12, Adam Bark wrote: On 27 June 2010 17:47, Payal c. What is the correct Python of writing, except as e: print 'Msg : ' , e# Capturing all exceptions Since exceptions are (should be?) subclasses of Exception, you can do: except Exception as e: I think the 'as' syntax is only available in Python 3.x It's in Python 2 as well. At least I see it in 2.6.4, probably earlier too (but I'm not sure ATM how early it showed up). ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] capturing error msg in exception
On 27 June 2010 18:22, Steve Willoughby wrote: > On 27-Jun-10 10:12, Adam Bark wrote: > >> On 27 June 2010 17:47, Payal > > > c. What is the correct Python of writing, >>except as e: print 'Msg : ' , e# Capturing all exceptions >> > > Since exceptions are (should be?) subclasses of Exception, you can do: > > except Exception as e: > > > I think the 'as' syntax is only available in Python 3.x >> > > It's in Python 2 as well. At least I see it in 2.6.4, probably earlier too > (but I'm not sure ATM how early it showed up). > > Ah yeah sorry I got confused, it's the comma version that is gone from 3.x isn't it? I assume that means 'as' is the preferred syntax. ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] OT: need computer advice from wise Tutors
On Sun, Jun 27, 2010 at 7:41 AM, Alan Gauld wrote: > "Marc Tompkins" wrote > > having no default email client (what sort of two-bit operating system >> >>> doesn't have an email client in 2010?); >>> >>> Jesus, you _miss_ Outlook Express? Seriously: the new default is >> webmail. >> Like it, don't like it, but it's really not as if you can't get your mail. >> > > I will miss OE. I actually quite like it, its simple but has all the bits > I need for both email and newrgroups. I tried thunderbird and use it > on my Linux box but on windows I usually revert to OE. > I always hated OE, but I suppose it does have its uses. Backing up OE was always problematic... > And its lots better than webmail which is only useful for occasional > browsing. But I get around 200 plus emails a day (and sometimes the > same again in news messages) and trying to manage that on webmail > is a nightmare - and you can't read it while offline. I really need an > offline mail client. As Richard mentioned and I will second, GMail handles that volume easily; Gears enables offline reading, and if you've drunk the Kool-Aid like I have, integration with Android is seamless. Also it's instantly portable from machine to machine. In any case, I only meant to whole-heartedly endorse upgrading from Vista to 7, and dismiss the loss of OE as a reason not to. Embracing the GMail way appears to be another one of those dreaded religious topics - I certainly can feel myself morphing into a ranting fanatic... > Just like XP and Vista, you're asked during installation whether you want >> to >> allow or disallow automatic updates. If you breeze past that question, >> then >> - just like in XP and Vista - you can right-click on the little icon that >> appears in your system tray (oops, I mean "notification area.") >> > > OOh. I've never noticed the icon - what does it look like? I didn't > do the install so had no say in the decision for work, but for my > home PC I'd much rather decide if/when I do "upgrades" - I've had > too mamy Windows upgrades kill my PC to the point of needing > rebuiilds! It looks like a rectangular pane of glass (a Window, maybe?) with an orange halo orbiting it. I don't see it on my machine at the moment (because I - wait for it - turned off automatic updates when I installed), so I'm a little fuzzy on whether it's a left-click, double-click, or right-click that gets you the option to turn off the auto updates. Regardless, here's a more direct way: Control Panel\System and Security\Windows Update\Change settings - Better wireless networking. Coming out of sleep or hibernation, it used > to take up to a minute and a half to connect to a known wireless network > I'll need to check that - I've just gotten used to going for a coffee when I > boot up - it usually takes me around 5 minutes for everything to get > started so I've never noticed the WiFi changes. I was driving on the freeway a while back, talking to my sister on the phone (hands-free!) when she mentioned that her computer was giving her trouble. I exited and pulled into a Starbucks I'd used before (so my machine already knew "attwifi7" or whatever it is). I opened my laptop, signed in, and used Chrome to sign into the AT&T captive portal; within less than a minute of my butt hitting the banquette I was in Copilot. She and I commiserated about the good old days when at least I could have ordered my coffee before I had to get down to work... 8-) -- www.fsrtechnologies.com ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] class questions
On Sun, Jun 27, 2010 at 6:47 PM, Shashwat Anand wrote: > >> >> The problem of the MRO isn't that it doesn't work, it's that it causes >> behavior that is unintuitive. In my example, We would expect D.x to be >> equal to C.x (since D inherits from C, and C overrides the x method). >> However, this is not the case. This is what the problem is with the >> old MRO system, not so much that it doesn't work at all, but the >> results aren't consistent with what you'd expect from multiple >> inheritance. >> > > I tried your example in python2.6 class A: > ... def x(self): return "in A" > ... class B(A): pass > ... class C(A): > ... def x(self): return "in C" > ... class D(B, C): pass > ... o = D() o.x() > 'in A' > If MRO was in python2.3, the output of o.x() should be 'in C'. It works fine > on 3.2alpha though. > You forgot that the example as is still uses the old MRO, even in 2.3. This is because these classes are still classic-style classes. To use the new MRO you will have to use new-style classes (A must inherit from object). In 3.x it will of course work fine, since everything without explicit inheritance inherits from object. Hugo ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] statements vs. expression and types
On Sun, Jun 27, 2010 at 6:57 PM, Payal wrote: > Hello, > Please forgive for such a silly questions. I have never taken a course on > computers so am rough with some of basic technical terminology. > > a. I read in a book that "lambdas are expressions ... so they can go > where functions are not allowed". What are expressions and what are > statements? A simple example of both in Python will suffice. > an expression is anything that yields a value. Simple expressions are 1 1 + 1 a [1, 2, 3] True and False lambda: 5 but anything that has a value is an expression. Expressions can be on the right side of an assignment statement. A statement is kind of the opposite. It does not have a value. Examples of statements: return 5 def x(): pass if True: sys.exit() while x < 4: pass > b. I read on web that Python has in new releases done "unifications of > types and classes". I know what classes are, what are types in simple > language. > a 'type,' in python before 2.2, was simply any of the builtin types, that is, int, str, list, dict, and so on. The unification that happened in 2.2 means that there are no more differences between a builtin 'type' and a user-defined 'class.' Nowadays a type is just any instance of the type class. Hugo ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] TypeError when io.open is used
Can you send the full error text please? I'm not sure which
is line 55 and Python normally displays the faulty line as
part of the error trace.
As it is I can't see any reason for it to fail but I'd like to
be sure I'm looking at the right place!
Also is there any reason why you explicitly call io.open()
instead of just using the built-in open() directly? I know
they are the same function but its quite unusual to use
the io version explicitly...
--
Alan Gauld
Author of the Learn to Program web site
http://www.alan-g.me.uk/
The full error message is:
Traceback :
File "insert_into_db_v9.py", line 55, in
WHERE testtable_n = %s""", data1,
str(os.path.splitext(file)[0]))
TypeError: an integer is required
And i would want to add that str() is not the problem. I have tried
without it and the problem persisted.
I have tried the following, too:
from pg8000 import DBAPI
import os
import os.path
import sys
# !!! that is test data. It must be changed
conn=DBAPI.connect(host="localhost", database="postgres",
user="postgres", password="test")
#conn.cursor will return a cursor oject, you can use this cursor to
perform queries
cursor = conn.cursor()
file = open(
"C:\\Blender_Library\\BlenderLib\\objectLib\\Faqns\\Osaka2\\faqns_osaka_2.jpg",
"rb" )
data1 = DBAPI.Binary(file.read())
data2 = 'faqns_osaka_2'
# execute our Query
cursor.execute("UPDATE testtable SET jpeg = %s WHERE testtable_n =
%s", data1, data2)
sys.stdout.flush()
# Save (commit) the changes
conn.commit()
# We can also close the cursor if we are done with it
cursor.close()
The problem this time was:
Traceback :
File "insertdb_pg8000.py", line 19, in
cursor.execute("UPDATE testtable SET jpeg = %s WHERE
testtable_n = %s", data1, data2)
File "build\bdist.win32\egg\pg8000\dbapi.py", line 243, in _fn
TypeError: execute() takes at most 3 arguments (4 given)
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Re: [Tutor] TypeError when io.open is used
On Sun, Jun 27, 2010 at 3:20 PM, wrote:
> I have tried the following, too:
>
> from pg8000 import DBAPI
> import os
> import os.path
> import sys
>
> # !!! that is test data. It must be changed
> conn=DBAPI.connect(host="localhost", database="postgres", user="postgres",
> password="test")
>
> #conn.cursor will return a cursor oject, you can use this cursor to perform
> queries
> cursor = conn.cursor()
>
> file = open(
> "C:\\Blender_Library\\BlenderLib\\objectLib\\Faqns\\Osaka2\\faqns_osaka_2.jpg",
> "rb" )
> data1 = DBAPI.Binary(file.read())
> data2 = 'faqns_osaka_2'
>
> # execute our Query
> cursor.execute("UPDATE testtable SET jpeg = %s WHERE testtable_n = %s",
> data1, data2)
> sys.stdout.flush()
>
> # Save (commit) the changes
> conn.commit()
>
> # We can also close the cursor if we are done with it
> cursor.close()
>
> The problem this time was:
> Traceback :
> File "insertdb_pg8000.py", line 19, in
> cursor.execute("UPDATE testtable SET jpeg = %s WHERE testtable_n =
> %s", data1, data2)
> File "build\bdist.win32\egg\pg8000\dbapi.py", line 243, in _fn
> TypeError: execute() takes at most 3 arguments (4 given)
>
>
I don't have any insight into your other piece of code, but here I think you
just need another set of parentheses - so that the string interpolation is
done first, and the result of it becomes the argument to cursor.execute().
I can't really test it at the moment, but try changing it to:
cursor.execute( ("UPDATE testtable SET jpeg = %s WHERE testtable_n = %s",
data1, data2) )
Either that, or break it into two lines:
myQuery = "UPDATE testtable SET jpeg = %s WHERE testtable_n = %s", data1,
data2
cursor.execute(myQuery)
--
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Re: [Tutor] OT: need computer advice from wise Tutors
On Mon, 28 Jun 2010 03:07:47 am Richard D. Moores wrote: > A "feature" very important to me > is that with Gmail, my mail is just always THERE, with no need to > download it You see your email without downloading it? You don't understand how the Internet works, do you? *wry grin* -- Steven D'Aprano ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] capturing error msg in exception
On Mon, 28 Jun 2010 03:12:39 am Adam Bark wrote: > I think the 'as' syntax is only available in Python 3.x You think wrong. It is available from Python 2.6 onwards. > Question marks go at the end of the sentence where you would normally > put a full stop if it wasn't a question. That's a terribly unhelpful answer given the context of Payal's question. I'm sure he knows the grammatical rules for questions in ordinary English sentences, but he's asking specifically about a particular form of sentence where you have a question consisting of two or more alternatives or examples separated as paragraphs: [example] Hello, which is better, a lambda: (1) lambda x: x+1 or a function definition: (2) def f(x): return x+1? [end example] It is very reasonable to ask where to put the question mark in examples like this. Unfortunately there is no good answer. If you put it on the same line as the second example, as shown, certainly isn't correct because it makes the question mark part of the example. It's *especially* dangerous in a programming context, because it leads to a syntax error. Putting it on a line on it's own after the example looks silly. Re-writing the question to avoid the problem is often awkward, but can be done: [rewritten example] Hello, which of these two are better? (1) lambda x: x+1 (2) def f(x): return x+1 [end rewritten example] Since there is no One Right Answer, you can do whichever seems best in context. -- Steven D'Aprano ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] TypeError when io.open is used
On Mon, 28 Jun 2010 08:20:01 am petko...@dir.bg wrote:
> The full error message is:
>
> Traceback :
> File "insert_into_db_v9.py", line 55, in
>WHERE testtable_n = %s""", data1,
> str(os.path.splitext(file)[0]))
> TypeError: an integer is required
Unfortunately this isn't helpful, because we're only seeing part of the
offending line of code. This is because Python tracebacks only show the
*physical* line which fails, but a logical line of code can be split
over more than one physical line.
E.g. if I have a module like this:
# test.py
x = 23
y = 23-x
z = (42/
y)
and then import it:
>>> import test
Traceback (most recent call last):
File "", line 1, in
File "test.py", line 5, in
y)
ZeroDivisionError: integer division or modulo by zero
it only shows me the last part of the expression (42/y).
So you will need to look at your source code and manually copy and paste
the rest of the logical line, that is, the line or lines immediately
before line 55.
> And i would want to add that str() is not the problem. I have tried
> without it and the problem persisted.
The call to str() is totally pointless, since os.path.splitext(file)[0]
is already a string.
[...]
> file = open(
> "C:\\Blender_Library\\BlenderLib\\objectLib\\Faqns\\Osaka2\\faqns_osa
>ka_2.jpg", "rb" )
Windows accepts forwards slashes for pathnames too, so the above can
more simply be written:
"C:/Blender_Library/BlenderLib/objectLib/Faqns/Osaka2/faqns_osaka_2.jpg"
with less chance of error.
> The problem this time was:
> Traceback :
> File "insertdb_pg8000.py", line 19, in
>cursor.execute("UPDATE testtable SET jpeg = %s WHERE
> testtable_n = %s", data1, data2)
> File "build\bdist.win32\egg\pg8000\dbapi.py", line 243, in _fn
> TypeError: execute() takes at most 3 arguments (4 given)
I'm afraid this is an example of a *slightly* misleading error message
in Python. the cursor.execute method takes at most three arguments:
# Something like this.
class Cursor:
def execute(self, a, b):
pass
*but* one of those arguments, self, is automatically filled in by
Python. So when you call execute, you can only supply TWO arguments:
cursor.execute(a, b)
If you provide three:
cmd = "UPDATE testtable SET jpeg = %s WHERE testtable_n = %s"
cursor.execute(cmd, data1, data2)
then Python fills in self and gives an error message that execute takes
only three arguments, not four.
So you need to read the documentation for execute to find out what
arguments it takes, because you can't pass all three of cmd, data1 and
data2.
--
Steven D'Aprano
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Re: [Tutor] OT: need computer advice from wise Tutors
On Sun, Jun 27, 2010 at 16:25, Steven D'Aprano wrote: > On Mon, 28 Jun 2010 03:07:47 am Richard D. Moores wrote: >> A "feature" very important to me >> is that with Gmail, my mail is just always THERE, with no need to >> download it > > You see your email without downloading it? You don't understand how the > Internet works, do you? I do, and I also know that you know what I meant. Dick ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] TypeError when io.open is used
On Sun, 27 Jun 2010 15:56:23 -0700
Marc Tompkins wrote:
On Sun, Jun 27, 2010 at 3:20 PM, wrote:
I don't have any insight into your other piece of code, but here
I think you
just need another set of parentheses - so that the string
interpolation is
done first, and the result of it becomes the argument to
cursor.execute().
I can't really test it at the moment, but try changing it to:
cursor.execute( ("UPDATE testtable SET jpeg = %s WHERE
testtable_n = %s",
data1, data2) )
Either that, or break it into two lines:
myQuery = "UPDATE testtable SET jpeg = %s WHERE testtable_n =
%s", data1,
data2
cursor.execute(myQuery)
-- www.fsrtechnologies.com
Thank you for the suggestion that i should enforce the parantheses. At
least that changed the error. Unfortunately that is wierd one, too:
Traceback :
File "insertdb_pg8000.py", line 20, in
cursor.execute( ("UPDATE testtable SET jpeg = %s WHERE
testtable_n = %s", data1, data2) )
File "build\bdist.win32\egg\pg8000\dbapi.py", line 243, in _fn
File "build\bdist.win32\egg\pg8000\dbapi.py", line 314, in execute
File "build\bdist.win32\egg\pg8000\dbapi.py", line 319, in
_execute
File "build\bdist.win32\egg\pg8000\interface.py", line 303, in
execute
File "build\bdist.win32\egg\pg8000\interface.py", line 108, in
_init_
File "build\bdist.win32\egg\pg8000\protocol.py", line 913, in _fn
File "build\bdist.win32\egg\pg8000\protocol.py", line 1048, in
parse
UnicodeDecodeError: 'ascii' codec can't decode byte 0xff in position
49: ordinal not in range()
I mean, as far as i know, for binary files i do not need to set
encoding when i open them.
PS: sorry for the direct E-Mail to Marc.
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Re: [Tutor] TypeError when io.open is used
On Sun, Jun 27, 2010 at 5:13 PM, wrote:
> On Sun, 27 Jun 2010 15:56:23 -0700
> Marc Tompkins wrote:
>
>> On Sun, Jun 27, 2010 at 3:20 PM, wrote:
>>
>> I don't have any insight into your other piece of code, but here I think
>> you
>> just need another set of parentheses - so that the string interpolation is
>> done first, and the result of it becomes the argument to cursor.execute().
>> I can't really test it at the moment, but try changing it to:
>> cursor.execute( ("UPDATE testtable SET jpeg = %s WHERE testtable_n = %s",
>> data1, data2) )
>>
>> Either that, or break it into two lines:
>>
>> myQuery = "UPDATE testtable SET jpeg = %s WHERE testtable_n = %s", data1,
>> data2
>> cursor.execute(myQuery)
>>
>> --
>> www.fsrtechnologies.com
>>
>
> Thank you for the suggestion that i should enforce the parantheses. At
> least that changed the error. Unfortunately that is wierd one, too:
>
> Traceback :
> File "insertdb_pg8000.py", line 20, in
>
> cursor.execute( ("UPDATE testtable SET jpeg = %s WHERE testtable_n =
> %s", data1, data2) )
> File "build\bdist.win32\egg\pg8000\dbapi.py", line 243, in _fn
> File "build\bdist.win32\egg\pg8000\dbapi.py", line 314, in execute
> File "build\bdist.win32\egg\pg8000\dbapi.py", line 319, in _execute
> File "build\bdist.win32\egg\pg8000\interface.py", line 303, in execute
> File "build\bdist.win32\egg\pg8000\interface.py", line 108, in _init_
> File "build\bdist.win32\egg\pg8000\protocol.py", line 913, in _fn
> File "build\bdist.win32\egg\pg8000\protocol.py", line 1048, in parse
> UnicodeDecodeError: 'ascii' codec can't decode byte 0xff in position 49:
> ordinal not in range()
>
> I mean, as far as i know, for binary files i do not need to set encoding
> when i open them.
>
OK - when I answered before, I was only looking at the error message and the
actual line of code that generated it; I hadn't really looked at what you're
trying to do.
Now that I've stepped back a bit, here's what I think you're trying to
achieve:
- open the file "faqns_osaka_2.jpg"
- read its contents
- write the contents to a BLOB field (or whatever the Postgres equivalent is
- anyway, a field that can hold an arbitrary chunk of data)
- write the name 'faqns_osaka_2' to a label field.
Unfortunately, you're trying to build the SQL command to do that using
string interpolation (the %s notation.) So your program gets as far as
reading the contents of the file, and then tries to decode them into a
string - and that's why you get this error. Be happy you got the error -
if it had succeeded, the resulting binary data would have been unreadable as
an image, and you wouldn't have known why.
I'm certain that there are proper ways to pass chunks of binary data for
insertion into BLOB fields - people must do this every day - but I don't
actually know them.
Here's a possibility:
http://book.opensourceproject.org.cn/lamp/python/pythoncook2/opensource/0596007973/pythoncook2-chp-7-sect-11.html
Or try searching for "python postgres blob".
--
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