🌐 Mailman 3 August 2004 - Python-list - python.org

how do i do this - stream file
by Ajay Aug. 3, 2004

Aug. 3, 2004

hi! How do i create and stream a file? On a webpage i have a link to a file. Next to it i would like link, which, when pressed, runs a script that calculates the signature of the file, pickles the signature to a file and then gives a dialog box asking the user whether they would like to save the file or open it. I have the script to do the signing and pickle the signature into a file, but how do i allow the user to download it? thanks cheers -- Ajay Brar, ---------------------------------------------------------------- This message was sent using IMP, the Internet Messaging Program.

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Unbinding sockets in threads..
by Richard Spooner Aug. 3, 2004

Aug. 3, 2004

Chaps, I've written a piece of python code below that when called with a line such as x = getdata(9999), listens on that port for data I'm sending it and puts the data in a list. If I delete x using del x and then try and assign a new value to port 9999 (e.g z=getdata(9999) ) then it reports that the socket it already bound, and I can't find any way of unbinding the port. If I try it not in a thread the del function works fine (i.e. creating and binding a socket s and then deleting it) Can anyone suggest some modifications I can do to make this work?? Thanks in advance Dave import threading import socket import struct import sys import time class getdata(threading.Thread): def __init__(self, port): threading.Thread.__init__(self) self.x = ['ZERO SPACE'] self.s = socket.socket( socket.AF_INET, socket.SOCK_DGRAM ) try: self.s.bind(( '', port)) except socket.error, msg: print "Could not bind to socket" time.sleep(3) self.s.close() sys.exit(1) self.carryon = 'true' self.start() def run(self): while self.carryon == 'true': self.data, self.addr = self.s.recvfrom( 1024 ) self.channel, self.value = struct.unpack( 'IBxxx' , self.data ) try: self.x[int(self.channel)] = self.value except IndexError: while len(self.x)-1 < int(self.channel): if len(self.x) == int(self.channel): self.x.append(self.value) else: self.x.append('NA') except: print "Dictionary creation error" time.sleep(3) self.s.close() sys.exit print self.x return

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Re: IronPython-0.6 is now available!
by "Martin v. Löwis" Aug. 3, 2004

Aug. 3, 2004

Derek Thomson wrote: > I haven't yet found the time to look at any of this stuff in detail, > but I will, and it wouldn't surprise me at all to learn that it was > really quite good in many respects - MS didn't just forge it all from > the ground up in total isolation, ignoring all that had gone before, > hoping to get it working right in the 3rd release. I have worked a lot with C# and .NET lately, and found two things: - the VM is very well designed. It does not really work for languages other than C#, though (and, yes: I believe that it does not work well for Python either, despite IronPython's existance (*)) - C# is ok. There are a few unfortunate (IMO) hacks, like the notion of delegates (which are the only callable objects), and the surprising behaviour wrt. to interfaces and overriding (where functions in a subclass won't implement an interface operation defined in the base class unless that implementation is virtual), but all in all, I can live with it. - The IDE is great; MSVC's type-ahead interface (or whatever it is called really saves a lot of typing an documentation lookup) - The standard library is both huge and awfully, terrible, and a huge hack. There is API for nearly any aspect of the system, but many aspects are ill-designed, apparently in an ad-hoc manner - the entire library appears to be written under great time pressure. The API is often counter-intuitive and does not provide features that people would expect, as very similar features are provided. For example, it has an interface API for relational databases, but it is not possible to write an application that is agnostic of the specific interface implementation, as the application always needs to create instances of specific implementation classes - they forgot to provide central factory functions. Regards, Martin

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file IO
by Darren Dale Aug. 3, 2004

Aug. 3, 2004

Can anyone explain this? I have a file called old.dat with two lines: 1 2 So it's 3 bytes long. I run the following: import os f = file('old.dat',mode='r') olddata = f.readlines() f.close() f = file('new.dat',mode='w') f.writelines(olddata) f.close() new.dat is now 4 bytes long. ??? I need to reformat and then save some data. Then I need to be able to export the reformatted data to a spreadsheet-friendly format. But once I have simply copied (trying to isolate the problem) the file using the script above, my export function takes 10x as long as it would have with the original file. And worse, the output has an extra newline character added at the end of each line. Any suggestions would really be appreciated, I am going a bit crazy trying to understand this. Darren

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RE: Call for Grant Proposals
by Tony Meyer Aug. 3, 2004

Aug. 3, 2004

[Maurice Ling] > Yes, exactly. You are correct to assume that it is logical to require > deliverables from this grant to be open sourced, however, > this cannot be inferred from the call for grant proposal's wordings > "The Python Software Foundation is seeking grant proposals for projects > related to the further development of Python, Python-related technology, > and educational resources." As I said before (and note that I'm not part of the PSF, or on the grants committee, or anything else like that), a call for proposals will never include every possible detail. If you want specifics, then you ask specific questions afterwards (and wait for a response from people who are probably pretty busy, no matter which grant committee this might be). In all likelihood, if someone put together a proposal that clearly would further develop Python in some fantastic way, was closed source, and the closed source nature didn't effect the development in any way, then the grants committee would be as likely to approve it as any other grant. > Although I may somewhat seems to want close > source development, my actual intentions is to refer to the grant > committee that by the actual wordings of the call allows for closed > source development. Unless there is a specific statement by the PSF > grant committee, I can foresee that companies may use this grant for > close sourced development. A grant committee can decide whether or not to give a grant to a particular requestee based on any criteria they like (providing it matches their given purpose). I'm sure the PSF would be fine receiving requests that deal with closed-source development. Like Tim said, it's likely that an open source project would benefit more people, and so more likely that it will beat out closed source competitors. That doesn't mean that it's impossible for a closed source project to get a grant. If your intent was to say "hey, it would help if you were more clear about these points", then an email saying that would have probably worked better <0.5 wink>. > Under common law, Whose? Melbourne's? Australia's? The USA's? It seems likely that it's the latter that would apply here, given that the PSF is a US organisation. > although PSF can attach further strings to the grant in the grant > letter, it is morally incorrect to do so. In what way? It certainly seems to me that the morally correct thing to do is to do their best in selecting projects that meet the stated aims of the grants. If that means an open source project, then it does. If that means a closed source project, then it does. > At the same time, although common law may allow such an act, I > am not too sure how this will seems in the eyes of equal opportunities > law and anti-discrimination laws, amongst others. It seems more than a stretch to apply those sorts of laws to a decision about particular licenses... > In either sense, I hate to think that I may eventually force > PSF to give me a grant for close sourced project. I imagine that everyone hates that idea. I can't see any possible way that you could do this, though, so we can all be relived <0.5 wink>. It really does seem that the appropriate move is to simply wait for someone from the grants committee to have time to respond to your questions. Isn't that what you would do with any other grant? (It's certainly what I would do). =Tony Meyer

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Re: flowcharting is automatic for Python via preprocessor
by Richard Hilburger Aug. 3, 2004

Aug. 3, 2004

As I read your comments, I found myself agreeing with each point. I feel that your analysis is quite good. I get the drift of your example at http://oregonstate.edu/~barnesc/temp/flow.pdf Well done. My detailed flow diagram is indeed "visually busy". After all, it shows every path leaving no room for misinterpretation. Your diagram method is like a shorthand version of my diagram method. Cleaner in appearance, but requiring more skill and experience to read it correctly. A tool such as the preprocessor I developed could easily have either a command-line flag or a user setting to let the user choose either detailed or less-detailed flow diagrams. Integration into a code editor is indeed a worthy goal, and if done well would very likely improve the appeal of any such methodology. I had thought of it, but decided to take an easier approach to test the water first. Do other editors do this? I don't know what is out there. Neil posted: http://www.eng.auburn.edu/grasp/index.html and I'll have to take a closer look at that. At first glance, it looks confusing and unappealing. <barnesc(a)onid.orst.edu> wrote in message news:mailman.1069.1091487166.5135.python-list@python.org... > > I like your idea. > > It is easy to get lost inside in eg a multiply nested if statement in a couple > multiply nested for loops, inside a try block. > > Sometimes one can split such code into separate functions, and this makes the > code cleaner. Sometimes not. > > However, the real issue is how the eye parses code. > > It's really inefficient to scan a whole page of code line by line to understand > where loops, branches, continues, and breaks occur. > > I think your visual diagrams could help, if they are: > > 1. Semantically cleaner. > IMO, there is too much detail in the flow diagrams. > (See http://www.getcet.org/images/ex3.png). > > A minimal amount of detail is easier to parse with the eye. > > See http://oregonstate.edu/~barnesc/temp/flow.pdf for a cleaner > example I came up with. This doesn't have arrows all over the > place (and hence may not be a flow diagram), but it does help > point out the relevant control structures. > > 2. Integrated into a code editor. > > I could see this being a new code editor fad, like collapsable > functions and classes. > > It could be quite useful, if the amount of visual information > is kept minimal, so that the coder is not distracted during > coding. > > If the flow diagrams are not integrated into an editor, I don't > think many coders will use them. > > Perhaps editors already do this. > > - Connelly

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How to clear previous console output?
by Newgene Aug. 3, 2004

Aug. 3, 2004

Hi, group, May I ask a newbie question? Given the below example: for i in range(100): print "%s%%" % i I want to show the progress by print 1% to 100%. But I hope each output will clear the previous output before print, so that I can see a dynamic updated display of percentage, instead of print all percentages one by one. How can I do that(what about on both windows and unix platform)? Thank you in advance for your expertise. Best, Cl

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Re: transforming a list into a string
by Dan Christensen Aug. 3, 2004

Aug. 3, 2004

Tim Peters <tim.peters(a)gmail.com> writes: > The only thing required of __iter__ is that it return an object that > supports the iteration protocol (meaning an object that supports > next() and __iter__() methods). So again, adding the ability to > slice too would mean requiring more of __iter__ methods -- or > changing the implementation of iter() to ignore __iter__ methods and > make something up itself. It's A Visible Change no matter how you > cut it. What if object[a:b:c] did the following? 1) if __getslice__ is supplied by object, use it. 2) if __getitem__ is supplied, use it. 3) if __iter__ is supplied, use islice(__iter__(object),slice(a,b,c)). (IIUC, 1) and 2) are what is done currently. As Christopher pointed out, for 3) to work, islice would have to modified to accept a slice.) Would this be backward compatible (a "Visible Change"), or would it break something? It seems to parallel other dispatching mechanisms, e.g. (IIUC) "in" is implemented just using the iterator protocol, unless the object supplies __contains__. I like the idea of not needing to know about islice, and just using the [a:b:c] notation. One of python's strongest features is its consistency of notation. Dan

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Microbenchmark: Summing over array of doubles
by bulatov＠engr.orst.edu Aug. 3, 2004

Aug. 3, 2004

I made an array of 10 million floats timed how long it takes to sum the elements, here's what I got (millis): gcc -O2: 21 Python with numarray: 104 Python with Numeric: 302 java: 325 gcc: 348 Python with Psyco: 1317 Pure Python using sum: 2312 Pure Python: 5631 http://yaroslav.hopto.org/russianwiki/index.php/c-numeric-speed numarray takes over Numeric at about 1100 floats I'm doing intensive computation on arrays in Python, so if you have suggestions on Python/C solutions that could push the envelope, please let me know. Yaroslav

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transforming a list into a string
by jblazi Aug. 3, 2004

Aug. 3, 2004

Let us assume I have a list like ['1','2','7','8','12','13] and would like to transoform it into the string '{1,2},{7,8},{12,13}' Which is the simplest way of achiebing this? (The list is in fact much longer and I may have to cut the resulting strings into chunks of 100 or so.) TIA, jb

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