🌐 Mailman 3 August 2000 - Python-list - python.org

Re: Difference between double and single quotes
by François Pinard Aug. 1, 2000

Aug. 1, 2000

[pauljolly(a)my-deja.com] > Please can someone tell me whether Python distinguishes between double > and single quotes in any way? This was brought to my attention by a > friend who queried my use of double and single quotes, saying that in > the UNIX shell a distinction is made. The Unix shell and Perl do a distinction, indeed, but Python does not. Being myself anal and needing a reason and motive for everything, I gave myself an artificial rule which I try to follow, but this is only a convention of mine, Python does not force me into anything. If the string is to be ultimately read by a human, I use "", when if the string is meant for the machine or algorithm mainly, I use ''. (This is not the same thing as the translatability of a string, which I mark by other means). Even if slightly fuzzy, this convention is best for me. I do prefer '' over "" in general as I find the former more readable, but the fact that the apostrophe is commonly used in human texts make "" more adequate. I usually prefer using \" within " strings and \' within ' strings, than to break my own convention. -- François Pinard http://www.iro.umontreal.ca/~pinard

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ANNOUNCE: xmlpickle.py 0.1
by John Wiegley Aug. 1, 2000

Aug. 1, 2000

This is a very poor man's XML pickling scheme, but I was unable to find anything else. It also provides a way of doing disk mirroring of in-memory objects. That is, the object is represented both in memory, as a Python object, and on disk, as an XML data file. Whichever one is changed first, the other will be updated appropriately on the next access to the object. To use this behavior, all that's necessary is: import xmlpickle class Derived(xmlpickle.Persistent): def __init__(self, name): xmlpickle.Persistent.__init__(self, name + ".xml") All changes to Derived objects will now be mirrored to name.xml files, which, if changed on disk, will alter their in-memory counterparts the next time someone accesses them. -----[ file: xmlpickle.py ]-------------------------------------------- import os import os.path import sys import time import types import string from xml.sax import saxexts from xml.dom.core import TEXT_NODE from xml.dom.builder import Builder from xml.dom.sax_builder import SaxBuilder class Renderable: def first_nontext_child(self, node, count = 0): for child in node.childNodes: if child.nodeType != TEXT_NODE: if count: count = count - 1 else: return child def input_data(self, node): if node.nodeName == 'string': text = "" for child in node.childNodes: text = text + child.nodeValue return text elif node.nodeName == 'int': text = "" for child in node.childNodes: text = text + child.nodeValue return int(string.strip(text)) elif node.nodeName == 'list': newlist = [] for item in node.childNodes: if item.nodeName != 'listitem': continue value = self.input_data(self.first_nontext_child(item)) newlist.append(value) return newlist elif node.nodeName == 'tuple': newtuple = () for item in node.childNodes: if item.nodeName != 'tupleitem': continue value = self.input_data(self.first_nontext_child(item)) newtuple = newtuple + (value,) return newtuple elif node.nodeName == 'hash': newhash = {} for item in node.childNodes: if item.nodeName != 'hashitem': continue hi = self.first_nontext_child(item) hk = self.first_nontext_child(hi) key = self.input_data(hk) hi = self.first_nontext_child(item, 1) hv = self.first_nontext_child(hi) value = self.input_data(hv) newhash[key] = value return newhash elif node.nodeName == 'type': obj = eval(node.attributes['name'])() return self.input_data(obj, node) else: pass # ignore tag def input_object(self, obj, node): for child in node.childNodes: if child.nodeName != 'property': continue data = self.input_data(self.first_nontext_child(child)) obj.__dict__[child.attributes['name'].value] = data def read_from_xml(self, file): "Read in the XML description of the project." # Create a SAX parser and a SaxBuilder instance p = saxexts.make_parser() dh = SaxBuilder() p.setDocumentHandler(dh) # Parse the input, and close the parser data = open(file, "r") p.parseFile(data) p.close() data.close() # Retrieve the DOM tree doc = dh.document return self.input_object(self, doc.documentElement) def output_data(self, builder, value, depth): vtype = type(value) if vtype == types.InstanceType: # Recursively process subobjects self.do_convert_to_dom(builder, value, depth) elif vtype == types.StringType: builder.text("\n" + (" " * depth)) builder.startElement('string') builder.text(value) builder.endElement('string') elif vtype == types.IntType: builder.text("\n" + (" " * depth)) builder.startElement('int') builder.text(str(value)) builder.endElement('int') elif vtype == types.ListType: builder.text("\n" + (" " * depth)) builder.startElement('list') for member in value: builder.text("\n" + (" " * (depth + 2))) builder.startElement('listitem') self.output_data(builder, member, depth + 4) builder.text("\n" + (" " * (depth + 2))) builder.endElement('listitem') builder.text("\n" + (" " * depth)) builder.endElement('list') elif vtype == types.TupleType: builder.text("\n" + (" " * depth)) builder.startElement('tuple') for member in value: builder.text("\n" + (" " * (depth + 2))) builder.startElement('tupleitem') self.output_data(builder, member, depth + 4) builder.text("\n" + (" " * (depth + 2))) builder.endElement('tupleitem') builder.text("\n" + (" " * depth)) builder.endElement('tuple') elif vtype == types.DictType: builder.text("\n" + (" " * depth)) builder.startElement('hash') for key, value in value.items(): builder.text("\n" + (" " * (depth + 2))) builder.startElement('hashitem') builder.text("\n" + (" " * (depth + 4))) builder.startElement('hashkey') self.output_data(builder, key, depth + 6) builder.text("\n" + (" " * (depth + 4))) builder.endElement('hashkey') builder.text("\n" + (" " * (depth + 4))) builder.startElement('hashvalue') self.output_data(builder, value, depth + 6) builder.text("\n" + (" " * (depth + 4))) builder.endElement('hashvalue') builder.text("\n" + (" " * (depth + 2))) builder.endElement('hashitem') builder.text("\n" + (" " * depth)) builder.endElement('hash') def do_convert_to_dom(self, builder, obj, depth = 2): builder.startElement('type', {"name": obj.__class__.__name__}) L = obj.__dict__.keys() L.sort() for attr in L: if attr[:1] == '__' or attr[:3] == "_v_": continue value = getattr(obj, attr) builder.text('\n' + (" " * depth)) builder.startElement('property', {"name": attr}) self.output_data(builder, value, depth + 2) builder.text('\n' + (" " * depth)) builder.endElement('property') builder.text('\n') builder.endElement('type') def write_to_xml(self, file): builder = Builder() self.do_convert_to_dom(builder, self) data = open(file, "w") data.write(builder.document.toxml()) data.close() class Persistent(Renderable): def __init__(self, filename): self.__dict__['_v_filename'] = filename self._revert_object(force = 1) def _revert_object(self, force = 0): """Check the XML representation of this object. If the memory resident copy is out of date, read it from disk again.""" if not self.__dict__.has_key('_v_filename'): return if not os.path.isfile(self.__dict__['_v_filename']): return mtime = os.stat(self.__dict__['_v_filename'])[8] if force or mtime > self.__dict__['_v_timestamp']: self.read_from_xml(self.__dict__['_v_filename']) self.__dict__['_v_timestamp'] = time.time() def _save_project(self): if not self.__dict__.has_key('_v_filename'): return self.write_to_xml(self._v_filename) self.__dict__['_v_timestamp'] = time.time() def __setattr__(self, prop, value): self.__dict__[prop] = value self._save_project() def __getattr__(self, prop): self._revert_object() return self.__dict__[prop] def __hasattr__(self, prop): self._revert_object() return self.__dict__.has_key(prop)

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Specifying a proxy server to be used for httplib???
by aj10＠my-deja.com Aug. 1, 2000

Aug. 1, 2000

The Internet in our office can only be accessed through a proxy server. I wanted to write a utility in Python that uses the httplib module to automate some routine searches. But I am stuck since there does not seem to be a way to access the Internet thru' the proxy. I am sure there is a very small thing which I am missing. Could someone please advise on how to channel the request thru' proxy and automate authentication? Thanks in advance Amit Sent via Deja.com http://www.deja.com/ Before you buy.

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Retrieving a query string from a <FORM ACTION> command
by Paul Goodyear Aug. 1, 2000

Aug. 1, 2000

Yep i'm a newbie here. Been doing this stuff for about a month and it rocks. The thing is I wrote a guestbook and for the last weeks it's been working fine. But all of a sudden the text that is sent to my server from the web page in the comments text input or textarea boxes are sent with +'s instead of spaces. I have tried both action="get" and action="post" in the HTML code. I have put the code below that does the grabbing: HTML CODE: --------------- <form method="get" action="/cgi-bin/guestbook.py"> PYTHON CODE: ------------------- import time, string, os print "Content-type: text/html\n\n" qs = os.environ['QUERY_STRING'] t = string.split(qs, "?") tt = string.split(t[0], '&') NameString = string.split(tt[0], '=') EmailString = string.split(tt[1], '=') CommentString = string.split(tt[2], '='); TimeString = time.ctime(time.time()) GuestList = open('cgi-bin/guestbook.txt') CurrentGuest = GuestList.readlines() GuestList.close() GuestList = open('cgi-bin/guestbook.txt', 'w') line = NameString[1] + ',' + EmailString[1] + ',' + CommentString[1] + ',' + TimeString + '\n' GuestList.write(line) GuestList.writelines(CurrentGuest) GuestList.close() I'm taking the query string and placing all the fields into variables, reading in the current entries and then writing them all out again. But as I said and why I need help is that all the spaces are now been replaced with + sysbols, which can I stress didn't do at first. I have changed the code and put it back and it did just the same. Please help. email or post.

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removing characters from a string?
by jesse＠multimediacollective.com Aug. 1, 2000

Aug. 1, 2000

say I had a string. this_string = "jesse(a)multimediacollective.com" """and I wanted to get rid of the @, how would I do that? This process has to be efficent for removing large quantities of special characters, such as <,>,#,%,* etc, from the same string. Any advice would be very helpful. Thanks in advance, Jesse.

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Re: to close or not to close?
by François Pinard Aug. 1, 2000

Aug. 1, 2000

[Thomas Wouters] > On Mon, Jul 31, 2000 at 02:48:02PM -0700, Grant Griffin wrote: > > Forgive me if this is a FAQ, but is it considered good Python form to > > close a file whose variable is just about to go out of scope (and thus > > be automatically closed)? Or should one just omit that? I came to consider it is a better form to _not_ close explicitely. Cases where explicit close is really useful are rather unusual, in my experience. In which cases, an explicit `close' gets more meaningful, and less noisy. And even then, I much prefer `file = None' than `close(file)', because the former really represents my intent: I promise I will not use `file' anymore. I like to think that closing a file is a system concern, not a user concern. > In current CPython it won't cause any problem to omit the close as long as > you are certain the vrbl will go out of scope, but JPython and possibly > other implementations of Python use true garbage collection (GC) rather > than reference counting (RC). This is true, and this is partly why I consider that CPython allows for less cluttered coding in such areas. I'm well prepared to revise my code if I ever need to use JPython. But until I do, I prefer clean and clear. > for x in [:256]: # or range(256) if you don't run experimental patches > open("tempfile.%d"%x) > Will work just fine in CPython, having open at most 2 'tempfiles' at once > (in an interactive session, that is, otherwise it has just 1 open.) I do not understand how we could have two. Since the result of `open' is not saved, I presume the file will be closed immediately after being opened, before executing the next instruction, or the next iteration. > But the same script under JPython, or a possible future CPython with true > GC, will run out of filedescriptors (or more likely: the max number of > open files) before the next GC run. On this list, I got a kind of guarantee that future CPython will stick with reference counting, possibly _complemented_ by more traditional mark and sweep. So, any current clean code will continue to work. -- François Pinard http://www.iro.umontreal.ca/~pinard

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file2lines
by Miki Tebeka Aug. 1, 2000

Aug. 1, 2000

Hello All, Is there a standard function that does something like this? def file2lines(file_name): lines = [] try: fp = open(file_name) lines = fp.readlines() fp.close() except: pass # ignore errors return lines And then you can just: for line in file2lines('myfile'): some_interesting_function(line) Bye. ------------------------------------------------------------------------------ Smile, damn it, smile. (lambda (msg) (case msg ((name) "Miki Tebeka") ((email) "tebeka(a)lycosmail.com") ((homepage) "http://www.tebeka.freeservers.com") ((quote) "I don't suffer from insanity, I enjoy every minute of it.")))

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Running IDLE other than root?
by Ryan Booz Aug. 1, 2000

Aug. 1, 2000

**** Post for FREE via your newsreader at post.usenet.com **** Hey all, I'm trying to do a quick learn of Python this summer to begin teaching it at school middle of the year. Compiled it the other night and have begun working through a book, "The Quick Python Book". Decided to try and use IDLE and when logged in as regular user, it give the message I've seen others getting: Traceback (innermost last): File "/usr/lib/python1.5/site-packages/idle.py", line 2, in ? import PyShell File "/usr/lib/python1.5/site-packages/PyShell.py", line 12, in ? from Tkinter import * File "/usr/local/lib/python1.5/lib-tk/Tkinter.py", line 8, in ? import _tkinter # If this fails your Python may not be configured for Tk ImportError: No module named _tkinter I understand that everyone (including the book) said that this is a Tk problem. Not being built. Thing is, when I log in as root (not su in), IDLE works fine. Importing of _tkinter works fine. Any thoughts? I would like to get this running. Of course I would like to try the Emacs helper also. thanks for the help, Ryan Booz Tech Coordinator Belleville Mennonite School -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-= *** Usenet.com - The #1 Usenet Newsgroup Service on The Planet! *** http://www.usenet.com -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=

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Python in politics (sssssssssnake!)
by Kirby Urner Aug. 1, 2000

Aug. 1, 2000

Something from another newsgroup but mentions Python, so I elected to cross-post (to the CIA group as well, because of the InQTel thing)[1]. For more context re the below, check: http://www.egroups.com/message/synergeo/1319 http://www.egroups.com/message/synergeo/1321 Also my "Math Makeover" homepage at: http://www.teleport.com/~pdx4d/makeover0.html The basic idea is to remix education topics to come up with more robust synergies (blah blah) i.e. get more kids doing Python programming around polyhedra, while watching TV shows which show how life in a Fly's Eye dome might be exciting, and useful to others (ala 'ER'). Kirby 4D Solutions .projects: videogrammatron, synergetics, philosophers network [1] http://www.in-q-tel.com/ Note: changed "Malthusian" to "Malthusian-minded" for a better read. ========================================================================= Newsgroups: bit.listserv.geodesic Date: Fri, 28 Jul 2000 09:37:43 -0700 Reply-To: List for the discussion of Buckminster Fuller's works <GEODESIC(a)LISTSERV.ACSU.BUFFALO.EDU> Sender: List for the discussion of Buckminster Fuller's works <GEODESIC(a)LISTSERV.ACSU.BUFFALO.EDU> From: Kirby Urner <pdx4d(a)TELEPORT.COM> Subject: Re: more late night synergetics Comments: cc: synergeo(a)egroups.com To: GEODESIC(a)LISTSERV.ACSU.BUFFALO.EDU At 08:55 AM 07/28/2000 -0700, Dick Fischbeck wrote: >Kirby-This is getting close to language I can really >grab onto. Would you rewrite this piece, say so that >an average sixth-grade could get it? >Thanks, >Dick I think for TV-immersed 6th graders these ideas would work best if presented as video with computer graphics. What we need is a databank of short videoclips, averaging under a minute in length, and retrievable by key word. You string these together or call them up in response to student questions. Hypertext interface. Distribution is by CDROM or DVD. In the USA, the Department of Education and DARPA should be pumping bucks into some prototypes, in consortium with the private sector (the corporations need not always be USA-based e.g. Sony), to catalyze a renaissance in education. A presidential candidate who doesn't speak in definite, clear terms about how she or he plans to revamp education is just blowing smoke, trying to get elected without doing the requisite homework. DARPA previously funded a "Computer Programming for Everybody" initiative (CP4E) designed to get more programming into the schools, with the Python language spearheading the effort.[1] That grant has long since run out, and is small change next to what's needed to spark imaginations around design science concepts more generally. Hollywood needs to get into the act, casting stars against a backdrop of futuristic artifacts that exists as working prototypes, not simply as phoney props or stage magician special effects. The game of brand placement (embedding logos in the actual programs, vs. separating out into separate advertising segments) will make a lot of sense in this context, as corporations vie with one another to prove their sponsorship of the "sexiest future" (e.g. Fly's Eye air-liftable utility pods, wired to cyberspace and staffed by youngsters with heavy duty real world responsibilities, ala ER -- real time camera access via webcam and TV segments (this is not a new theme for me -- shows like 'Survivor' bring us closer)). We're in dire need of a realistic futurism, an attainable positive tomorrow. Because a self-indulgent and Malthusian-minded academia has fallen down on the job (by and large), Federation pseudo-Science ala Star Trek has been allowed to fill the cultural void, holding out the prospect of a high tech future, but using mumbo jumbo concepts instead of hard science-math, leaving kids to fantasize helplessly about some 24th century, while Spaceship Earth meanwhile remains in the grip of obsolete power structures, desparate to hang on to power (the Napster fracas being just the tip of the iceberg vis-a-vis that juggernaut).[2] A lot of intellectuals overseas are well-aware of how USA politicos are consistently and concertedly ignoring their leadership responsibilities, which include inspiring positive future visions, vs. simply serving as the puppets and task masters of those who see humans as little more than exploitable consumers. This has the effect or eroding the credibility and even the comprehensibility of the political leadership. Why don't they make any sense? Education is from the inside out, but the inner world has been left in the hands of media manipulators who fill heads with cheap googoo-brained claptrap, whatever it takes to create a new generation of mall rats and fast food junkies. The USA, such as it still exists, is working to counter that diet, with healthful content -- design science based positive future imagery, backed up with real math and science, being chief among the vitamins and minerals we need to firm up our jello-brained culture. We should start a race to see which presidential candidate we can get to say "Buckminster Fuller" on TV first. The Republicans have an edge, because President Reagan awarded Bucky the Medal of Freedom. But Gore is into the internet, and that's a relevant segue to design science as well. Nader is highly critical of corporations ala 'Grunch of Giants' and so has plenty of hooks. There's nothing stopping any of these campaigns from jumping on the design science bandwagon and demonstrating some ability to point towards a positive future for all humanity. Any candidate who fails to lead the way to a better tomorrow ipso facto fails the minimum test for leadership ability, in my book. Kirby [1] CP4E: http://www.python.org/doc/essays/cp4e.html [2] http://www.salon.com/tech/col/rose/2000/07/27/napster_shutdown/index.html

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Newbie pythoner, with bizzare problem
by milenko＠moonshine.co.uk Aug. 1, 2000

Aug. 1, 2000

Hey there, im pretty new to using python, and im just experimenting with file access, a wrote a script that works fine, and then all of a sudden it started throwing up this error: inp = open("c:/autoexec.bat",'r') TypeError: illegal argument type for built-in operation it was working fine before, and i dont see anything unusual in the syntax. Any help would be appreciated, Cheers, Jack Green

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