🌐 Mailman 3 September 2007 - Python-list - python.org

Re: Pythonwin Install COM exceptions on Windows Vista Ultimate
by M�ta-MCI (MVP) Sept. 2, 2007

Sept. 2, 2007

Hi! Perso, on Vista, I : - deactive UAC - deactive firewall (I have a rooter) - run all like Administrator - install all in other DIR than "Program Files" Result : no problem.

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Re: list index()
by zzbbaadd＠aol.com Sept. 2, 2007

Sept. 2, 2007

> > How could it not be an exception, in the plain English sense of the > word? Most certainly you're asking for the index because you want to do > something with the index. If the item is not found, you have no index, > so that's a special case that must be handled separately. There is no > logical difference between handling that special case in an except > clause versus handling it with an if-branch. In my case of have done os.listdir() on two directories. I want to see what files are in directory A that are not in directory B. I have used exceptions in other languages and only do so on logic that should never happen. In this case it is known that some of the files will not be in both lists. I just want to know which ones.

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Re: localizing a sort
by Peter Otten Sept. 2, 2007

Sept. 2, 2007

Am Sat, 01 Sep 2007 18:56:38 -0300 schrieb Ricardo Aráoz: > Hi, I've been working on sorting out some words. > > My locale is : >>>> import locale >>>> locale.getdefaultlocale() > ('es_AR', 'cp1252') > > I do : >>>> a = 'áéíóúäëïöüàèìòù' >>>> print ''.join(sorted(a, cmp=lambda x,y: locale.strcoll(x,y))) > aeiouàáäèéëìíïòóöùúü The lambda is superfluous. Just write cmp=locale.strcoll instead. > This is not what I am expecting. I was expecting : > aáàäeéèëiíìï.....etc. > > The reason is that if you want to order some words (say for a dictionary > (paper dict, where you look up words)) this is what happens : >>>> a = 'palàbra de pàlabra de pblabra' >>>> print ' '.join(sorted(a.split(), cmp=lambda x,y: locale.strcoll(x, y))) > de de palàbra pblabra pàlabra > > While any human being would expect : > > de de palàbra pàlabra pblabra > > Does anybody know a way in which I could get the desired output? I suppose it would work on your machine if you set the locale first with >>> locale.setlocale(locale.LC_ALL, "") 'de_DE.UTF-8' I have to resort to a list instead of a string on mine because it uses the UTF-8 encoding where one character may consist of more than one byte. (Providing key is more efficient than cmp.) >>> a = ['á', 'é', 'í', 'ó', 'ú', 'ä', 'ë', 'ï', 'ö', 'ü', 'à', 'è', 'ì', 'ò', 'ù', 'a', 'e', 'i', 'o', 'u'] >>> print "".join(sorted(a, key=locale.strxfrm)) aáàäeéèëiíìïoóòöuúùü However, to make your program a bit more portable I recommend that you use unicode instead of str: >>> import locale >>> locale.setlocale(locale.LC_ALL, "") 'de_DE.UTF-8' >>> encoding = locale.getlocale()[1] >>> def sortkey(s): ... return locale.strxfrm(s.encode(encoding)) ... >>> print "".join(sorted(u"áéíóúäëïöüàèìòùaeiou", key=sortkey)) aáàäeéèëiíìïoóòöuúùü >>> Peter

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Re: status of Programming by Contract (PEP 316)?
by aleax＠mac.com Sept. 2, 2007

Sept. 2, 2007

Ricardo Aráoz <ricaraoz(a)gmail.com> wrote: ... > >> We should remember that the level > >> of security of a 'System' is the same as the level of security of it's > >> weakest component, ... > You win the argument, and thanks you prove my point. You typically > concerned yourself with the technical part of the matter, yet you > completely ignored the point I was trying to make. That's because I don't particularly care about "the point you were trying to make" (either for or against -- as I said, it's a case of ROI for different investments [in either security, or, more germanely to this thread, reliability] rather than of useful/useless classification of the investments), while I care deeply about proper system thinking (which you keep failing badly on, even in this post). > In the third part of your post, regarding security, I think you went off > the road. The weakest component would not be one of the requisites of > access, the weakest component I was referring to would be an actual > APPLICATION, Again, F- at system thinking: a system's components are NOT just "applications" (what's the alternative to their being "actual", btw?), nor is it necessarily likely that an application would be the weakest one of the system's components (these wrong assertions are in addition to your original error, which you keep repeating afterwards). For example, in a system where access is gained *just* by knowing a secret (e.g., a password), the "weakest component" is quite likely to be that handy but very weak architectural choice -- or, seen from another viewpoint, the human beings that are supposed to know that password, remember, and keep it secret. If you let them choose their password, it's too likely to be "fred" or other easily guessable short word; if you force them to make it at least 8 characters long, it's too likely to be "fredfred"; if you force them to use length, mixed case and digits, it's too likely to be "Fred2Fred". If you therefore decide that passwords chosen by humans are too weak and generate one for them, obtaining, say, "FmZACc2eZL", they'll write it down (perhaps on a post-it attached to their screen...) because they just can't commit to memory a lot of long really-random strings (and nowadays the poor users are all too likely to need to memorize far too many passwords). A clever attacker has many other ways to try to steal passwords, from "social engineering" (pose as a repair person and ask the user to reveal their password as a prerequisite of obtaining service), to keystroke sniffers of several sorts, fake applications that imitate real ones and steal the password before delegating to the real apps, etc, etc. Similarly, if all that's needed is a physical token (say, some sort of electronic key), that's relatively easy to purloin by traditional means, such as pickpocketing and breaking-and-entering; certain kind of electronic keys (such as the passive unencrypted RFID chips that are often used e.g. to control access to buildings) are, in addition, trivially easy to "steal" by other (technological) means. Refusing to admit that certain components of a system ARE actually part of the system is weak, blinkered thinking that just can't allow halfway decent system design -- be that for purposes of reliability, security, availability, or whatever else. Indeed, if certain part of the system's architecture are OUTSIDE your control (because you can't redesign the human mind, for example;-), all the more important then to make them the focus of the whole design (since you must design AROUND them, and any amelioration of their weaknesses is likely to have great ROI -- e.g., if you can make the users take a 30-minutes short course in password security, and accompany that with a password generator that makes reasonably memorable though random ones, you're going to get substantial returns on investment in any password-using system's security). > e.g. an ftp server. In that case, if you have several > applications running your security will be the security of the weakest > of them. Again, false as usual, and for the same reason I already explained: if your system can be broken by breaking any one of several components, then it's generally WEAKER than the weakest of the components. Say that you're running on the system two servers, an FTP one that can be broken into by 800 hackers in the world, and a SSH one that can only be broken into by 300 hackers in the world; unless every single one of the hackers who are able to break into the SSH server is *also* able to break into the FTP one (a very special case indeed!), there are now *MORE* than 800 hackers in the world that can break into your system as a whole -- in other words, again and no matter how often you repeat falsities to the contraries without a shred of supporting argument, your assertion is *FALSE*, and in this case your security is *WEAKER* than the security of the weaker of the two components. I do not really much care what point(s) you are trying to make through your glib and false assertions: I *DO* care that these falsities, these extremely serious errors that stand in the way of proper system thinking, be never left unchallenged and uncorrected. Unfortunately a *LOT* of people (including, shudder, ones who are responsible for architecting, designing and implementing some systems) are under very serious misapprehensions that impede "system thinking", some of the same ilk as your falsities (looking at only PART of the system and never the whole, using far-too-simplified rules of thumbs to estimate system properties, and so forth), some nearly reversed (missing opportunities to make systems *simpler*, overly focusing on separate components, &c). As to your specific point about "program proofs" being likely overkill (which doesn't mean "useless", but rather means "low ROI" compared to spending comparable resources in other reliability enhancements), that's probably true in many cases. But when a probably-true thesis is being "defended" by tainted means, such as false assertions and excessive simplifications that may cause serious damage if generally accepted and applied to other issues, debunking the falsities in question is and remains priority number 1 for me. Alex

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ANN: Python bindings for mjpegtools (yuv4mpeg)
by DavidM Sept. 2, 2007

Sept. 2, 2007

Hi, I've built some bindings for the yuv4mpeg API, supporting both Python and C++. http://www.freenet.org.nz/pyyuv4mpeg/ Based on SWIG, implements virtually the whole API as given in yuv4mpeg.h, and also implements a high-level 'Stream' class in both C++ and Python. These bindings allow easy creation of video filters, in Python or C++, that work to the mjpegtools 'yuv4mpegpipe' standard - reading YUV4MPEG frames into stdin and/or writing YUV4MPEG frames to stdout. Enjoy Cheers David

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Re: So what exactly is a complex number?
by Tim Daneliuk Sept. 2, 2007

Sept. 2, 2007

Grzegorz Słodkowicz wrote: > >> Here is a simple explanation (and it is not complete by a long shot). >> >> A number by itself is called a "scalar". For example, when I say, >> "I have 23 apples", the "23" is a scalar that just represents an >> amount in this case. >> >> One of the most common uses for Complex Numbers is in what are >> called "vectors". In a vector, you have both an amount and >> a *direction*. For example, I can say, "I threw 23 apples in the air >> at a 45 degree angle". Complex Numbers let us encode both >> the magnitude (23) and the direction (45 degrees) as a "number". >> >> There are actually two ways to represent Complex Numbers. >> One is called the "rectangular" form, the other the "polar" >> form, but both do the same thing - they encode a vector. >> >> Complex Numbers show up all over the place in engineering and >> science problems. Languages like Python that have Complex Numbers >> as a first class data type allow you do to *arithmetic* on them >> (add, subtract, etc.). This makes Python very useful when solving >> problems for engineering, science, navigation, and so forth. >> >> >> HTH, >> > You're mixing definition with application. You didn't say a word about > what complex numbers are, not a word about the imaginary unit, where I was trying to motivate the idea by means of analogy. This is a legitimate thing to do. It helps lead people to a conceptual understanding long before they understand the minutae. I am well aware of the imaginary unit and from whence complex analysis springs. I just didn't think that was the best place to start explicating the *concept*. I find concrete examples that then can lead to theoretical underpinnings a better way to go than the reverse. It is so hard to grasp that learning happens in layers, and that each layer need not be complete or even precise? Evidently you've either never taught (or were very bad at it). You have to motivate concept and interest before you can get to the precise detail. For instance, you start with Newtonian physics, not quantum physics. The entry level physics classes ignore things like the the non-linear behavior of springs, or the effects when you don't actually do things in a vacuum. By your definition these lectures would be "wrong" .. but they're not. They are attempting to introduce a topic painlessly. And that's what I was doing. > does it come from, why is it 'imaginary' etc. Since we're being arses > here I'd hazard a guess you were educated in the USA where doing without > understanding has been mastered by teachers and students alike. You're I was initially educated in Europe where being rude was sometimes encouraged to mask insecurity with a false sense of self-importance. I was later educated in both Canada and the US wherein I learned both they "why" and the how". -- ---------------------------------------------------------------------------- Tim Daneliuk tundra(a)tundraware.com PGP Key: http://www.tundraware.com/PGP/

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Re: So what exactly is a complex number?
by Tim Daneliuk Sept. 2, 2007

Sept. 2, 2007

Carsten Haese wrote: > On Thu, 2007-08-30 at 20:11 -0500, Lamonte Harris wrote: >> Like in math where you put letters that represent numbers for place >> holders to try to find the answer type complex numbers? > > Is English your native language? I'm having a hard time decoding your > question. > Here is a simple explanation (and it is not complete by a long shot). A number by itself is called a "scalar". For example, when I say, "I have 23 apples", the "23" is a scalar that just represents an amount in this case. One of the most common uses for Complex Numbers is in what are called "vectors". In a vector, you have both an amount and a *direction*. For example, I can say, "I threw 23 apples in the air at a 45 degree angle". Complex Numbers let us encode both the magnitude (23) and the direction (45 degrees) as a "number". There are actually two ways to represent Complex Numbers. One is called the "rectangular" form, the other the "polar" form, but both do the same thing - they encode a vector. Complex Numbers show up all over the place in engineering and science problems. Languages like Python that have Complex Numbers as a first class data type allow you do to *arithmetic* on them (add, subtract, etc.). This makes Python very useful when solving problems for engineering, science, navigation, and so forth. HTH, -- ---------------------------------------------------------------------------- Tim Daneliuk tundra(a)tundraware.com PGP Key: http://www.tundraware.com/PGP/

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howto compile recursively all *.py files to *.pyc (from a directory my_dir)?
by dmitrey Sept. 2, 2007

Sept. 2, 2007

howto compile recursively all *.py files to *.pyc (from a directory my_dir)? Thank you in advance, D.

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Re: How best to dynamically define methods (and functions)?
by Bjoern Schliessmann Sept. 2, 2007

Sept. 2, 2007

Kenneth McDonald wrote: > I can see an obvious but hacky way to define a Python function at > runtime. What way is this? All Python function definitions in your code are executed at runtime. > In case it's of interest in the context of the question, I need to > define a largish set of functions (and similar methods) that > define a XML-type markup language. Most of these functions will > just be of the form > > def fun(...): > return Node('fun', ...) > > so it'd definitely be nice to just create most of them > automatically, and only do the special cases by hand. This looks cumbersome to me. If you reworked the interface (perhaps using dicts or a generic function) it might get clearer. Regards, Björn -- BOFH excuse #241: _Rosin_ core solder? But...

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Windows Media Player Playlist
by Lamonte Harris Sept. 2, 2007

Sept. 2, 2007

Is it possible to use python to get the current playlist of the current playing songs from Windows Media Player or Windows Player Classic?

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