🌐 Mailman 3 January 2004 - Tutor - python.org

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by dana＠momerath.us Feb. 4, 2004

Feb. 4, 2004

From: Dana Baguley <dana(a)momerath.us> To: tutor(a)python.org Subject: HTMLParser Date: Sat, 31 Jan 2004 04:37:18 -0800 User-Agent: KMail/1.5.4 MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200401310437.18353.dana(a)momerath.us> Status: RO X-Status: Q X-KMail-EncryptionState: X-KMail-SignatureState: Hello, I'm new to python and pretty new to programming in general. As a first project, I'm trying to write a program to pull data from tables on webpages. I'm having trouble with the HTMLParser module. Below is my code and the error message. I'm thinking I should be using the debugger for this, but I don't have a clue where to start so I'm emailing the list instead. Thanks in advance. Also, this is my first email to a list like this one, so I'm wondering if I'm observing proper social conventions. This message feels kind of long to me. What do you think? Dana #r.py import HTMLParser import urllib import string def getPage(address): page = urllib.urlopen(address) page = page.readlines() return page def flattenPage(page): returned = '' for line in page: returned +=line returned += ' ' for character in string.whitespace: # probably not necessary to zap newlines. returned = string.replace(returned, character, ' ') return returned def getFlatPage(URL): page = flattenPage(getPage(URL)) return page class InteractiveURLParser(HTMLParser.HTMLParser): def open(self, URL): page = getPage(URL) page = flattenPage(page) self.feed(page) def newURL(self, URL): __init__(self, URL) def handle_starttag(self, tag, attrs): print "tag is %s with attributes %s." %(self, tag, attrs) def handle_data(self, data): print data -- >>> carrie = "http://www.plu.edu/~swarthcj" >>> r.test(carrie) Traceback (most recent call last): File "<stdin>", line 1, in ? File "r.py", line 37, in test testInstance.open(URL) File "r.py", line 27, in open self.feed(page) File "/usr/lib/python2.3/HTMLParser.py", line 108, in feed self.goahead(0) File "/usr/lib/python2.3/HTMLParser.py", line 148, in goahead k = self.parse_starttag(i) File "/usr/lib/python2.3/HTMLParser.py", line 281, in parse_starttag self.handle_starttag(tag, attrs) File "r.py", line 31, in handle_starttag print "tag is %s with attributes %s." %(self, tag, attrs) TypeError: not all arguments converted during string formatting

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special call for deleted objects?
by Thomas Clive Richards Feb. 3, 2004

Feb. 3, 2004

Hi Guys, I've got a list of class instances, and under certain conditions, I want to replace them with None. However, these instances should do some cleanup before they dissapear. I *could* create a cleanup method, and call it specifically every time I want to delete the instance, and then replace it with None, but I thought there might be a special method that automatically gets called when an object is deleted. Am I on the right track? I took a browse through the docs, and couldn't see any mention of such a method, but maybe it's hidden away for a reason... Is following this train of thought more trouble than it's worth? (probably I'm guessing)... Thanks... -- Thomi Richards, thomi(a)once.net.nz

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do pythons like coffee?
by Kirk Bailey Feb. 1, 2004

Feb. 1, 2004

I am studying JavaScript of late. And it occurs to me that a script pumping out a webpage might use a little javascript in it for assorted nefarious purposes. Anyone familiar with the friendlyness of these two unlikely bedfellows? EGODS, the thought of a python STOKED on caffene... -- end think http://www.tinylist.org/ - $FREE$ software for liberty +-------+ http://www.pinellasintergroupsociety.org/ - In Her Service | BOX | http://www.listville.net/ - $FREE$ list hosting services +-------+ http://www.howlermonkey.net/ - $FREE$ email service kniht http://www.sacredelectron.org/ - My personal SCREED pit (C)2004 Kirk D Bailey, all rights reserved- but ask!

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Re: [Tutor] Cannot fix OSError
by Nick Lunt Jan. 31, 2004

Jan. 31, 2004

Many thanks for your responses. On Fri, 30 Jan 2004 18:26:10 -0800 (PST) Danny Yoo <dyoo(a)hkn.eecs.berkeley.edu> wrote: > Oh! Here is one possibility: the files listed in sys.argv[2:] may be > directories. It's possible that tarfile.TarFile.add() can take in either > directories or filenames. That is, the directory > > /etc > > might be listed in sys.argv[2:], and technically speaking, '/etc' is > completely readable. But if tarfile recursively dives into a directory, > it might run into: > > /etc/skel/tmp > > and run into problems tarring that file. The test for readability in the > code you've written only looks at the files explicitely listed on the > command line. I think my main error is as Danny Voo states, the fact that I sent in /etc which can be read fine, but some files beneath it can't. Thanks for that Danny, now I've seen how you've done it I'll try not to look at it again so I can try it myself ;) And thanks for the links too. On Sat, 31 Jan 2004 09:01:38 -0000 "Alan Gauld" <alan.gauld(a)blueyonder.co.uk> wrote: > What's wrong with a try/except approach: Alan, I agree the try/except method would help, but I wanted to understand why my if statement wasn't working 100%, the final version of my prog will include several try/except blocks On Sat, 31 Jan 2004 04:44:49 +0100 jb <jb(a)riseup.net> wrote: > basically you can't tar a directory that doesnt have r and x fields set Thanks jb, I understand the unix permissions and thought my if block would filter out that problem, but obviously I didn't think about it hard enough ;) Anyway, thanks again for all your help. Cheers Nick.

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Re: [Tutor] Cannot fix OSError (try/except)
by Nick Lunt Jan. 31, 2004

Jan. 31, 2004

With the help I've received so far I've decided (but not yet coded) that the original 'if os.access('wherever', os.R_OK):' will be able to handle files passed on the command line fine, but directories will need to be walked so that any subdirectories/files can be handled seperately. Something along the lines of arglist = sys.argv[2:] for f in arglist: if os.path.isdir(f): # it's a dir <send it off to a func for a dir walk and access check> if os.access(f, os.R_OK): # it's a file <add it to the final list of files to be tarred> Well that makes sense to me anyway - thanks to you folks ;) Cheers Nick. On Sat, 31 Jan 2004 21:54:42 -0000 "Alan Gauld" <alan.gauld(a)blueyonder.co.uk> wrote: > > You can pass the name of a directory. If it can't read a file > within > > the directory, it abandons the rest of the directory contents. I > just > > tested that. The except will continue to the next file/directory in > YOUR > > list, but you've potentially skipped readable files in the directory > with > > an error. > > But doesn't the OK check do the same? You would need to do a > tree walk to avoid that, wouldn't you? > > Alan G.

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Re: [Tutor] Re: do pythons like coffee?
by Lee Harr Jan. 31, 2004

Jan. 31, 2004

>>>I am studying JavaScript of late. And it occurs to me that a script >>>pumping out a webpage might use a little javascript in it for assorted >>>nefarious purposes. Anyone familiar with the friendlyness of these two >>>unlikely bedfellows? >>> >> >> >>I guess my response would be ... it is no more dangerous than serving >>a plain text file with a malicious javascript on it. >> >>The nice thing about server-side scripting (and why I prefer it to the >>client-side scripts) is that it's all the same to the browser. On the >>server it might be pulling in pieces from all over the place -- templates, >>scripts, configuration files, environment variables -- but in the end it >>sends out a stream of bytes and the client just sees it as a file. >> > >I use javascript most commonly for POSTs that look like hyperlinks (GETs). >The >javascript is embedded in the href attribute of the anchor tag, sets >some variables and calls the form's submit function. > Right. That goes to my point... On my main browser, I have javascript completely disabled. I find it really annoying when I get to a link that looks like a regular link, but does nothing unless javascript is enabled. _________________________________________________________________ Help STOP SPAM with the new MSN 8 and get 2 months FREE* http://join.msn.com/?page=features/junkmail

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Re: do pythons like coffee?
by Lee Harr Jan. 31, 2004

Jan. 31, 2004

>I am studying JavaScript of late. And it occurs to me that a script >pumping out a webpage might use a little javascript in it for assorted >nefarious purposes. Anyone familiar with the friendlyness of these two >unlikely bedfellows? > I guess my response would be ... it is no more dangerous than serving a plain text file with a malicious javascript on it. The nice thing about server-side scripting (and why I prefer it to the client-side scripts) is that it's all the same to the browser. On the server it might be pulling in pieces from all over the place -- templates, scripts, configuration files, environment variables -- but in the end it sends out a stream of bytes and the client just sees it as a file. _________________________________________________________________ Protect your PC - get McAfee.com VirusScan Online http://clinic.mcafee.com/clinic/ibuy/campaign.asp?cid=3963

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raw_input function
by Christopher Spears Jan. 31, 2004

Jan. 31, 2004

Where can I go to get some general information on how the raw_input function works? -Chris ===== "I'm the last person to pretend that I'm a radio. I'd rather go out and be a color television set." -David Bowie "Who dares wins" -British military motto "Far more creativity, today, goes into the marketing of products than into the products themselves..." -"Pattern Recognition" by William Gibson

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Cannot fix OSError
by Nick Lunt Jan. 31, 2004

Jan. 31, 2004

Hi Folks, this is my first posting to the list, although I have been snooping for a couple of weeks ;) I've recently started to learn Python and so far I'm having great fun. Anyway, here's my problem, first off here's the program: # code import tarfile, sys, os if len(sys.argv) <= 2: print 'Error:', sys.argv[0], ' <tarfile.tar> <list of files> sys.exit(1) tfile = sys.argv[1] totar = [] for f in sys.argv[2:]: if os.access(f, os.R_OK): # NOTE1 totar.append(f) else: print 'Could not access', f, 'to tar' tf = tarfile.TarFile(tfile, 'w') for f in totar: tf.add(f) tf.close # end code This works fine until it encounters a file that I am not allowed to access, in which case it gives me this error: # error Traceback (most recent call last): File "./tar.py", line 31, in ? tf.add(f) File "/usr/lib/python2.3/tarfile.py", line 1220, in add self.add(os.path.join(name, f), os.path.join(arcname, f)) File "/usr/lib/python2.3/tarfile.py", line 1220, in add self.add(os.path.join(name, f), os.path.join(arcname, f)) File "/usr/lib/python2.3/tarfile.py", line 1219, in add for f in os.listdir(name): OSError: [Errno 13] Permission denied: '/etc/skel/tmp' # end error I could trap it in a try/except OSError block, but I'd like to know why the line NOTE1 does not simply cause the program to skip the unreadable file and continue ? >From the python interpreter 'os.access('/file/i/cant/read', os.R_OK)' returns False so I expected my 'if' on line NOTE1 to sort that out. If someone could just explain to me where I'm going wrong I'd be extremely greatful. Many thanks Nick.

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Re: [Tutor] Converting string or list to sum
by Isr Gish Jan. 31, 2004

Jan. 31, 2004

Kalle Svensson Wrote: >[Daniel Ehrenberg] >> >> > > I think I can put two ideas together to solve it >> > for lists : >> > > >>> a=[2, 3, '+', 4] >> > > >>> d="" >> > > >>> for item in range(len(a)): >> > > ... d=d+str(a[item]) >> > > ... >> > >> > Or even easier: >> > >> > for item in a: >> > d = d + str(item) >> > >> > No need for indexing etc, >> > >> > Alan G. >> >> In that case, is there any reason not to just do >> >> for item in a: >> d += str(item) > >I'd write > > d = ''.join(map(str, a)) > >since that's probably much faster for large lists. > I think that should be: import __builtin__ d = ''.join(map(__builtin__.str, a)) Good luck Isr

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