🌐 Mailman 3 March 1999 - Tutor - python.org

programming
by StnCold180＠aol.com April 4, 1999

April 4, 1999

Hi. I am real interested in learning Python, but how do I go about starting? What do I need? can you help? Thanx, John Akles (stncold180(a)aol.com)

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RE: [Tutor] chemical formula
by alan.gauld＠bt.com March 31, 1999

March 31, 1999

> understand it. I have yet to read a good tutorial on OOP for > the novice. Marginally off topic but I found Timothy Budd's OOP book excellent. he uses several OOP languages to illustrate(Smalltalk, C++, Java, Delphi(OP) - I think they are) so you don't get hung up on a single languages view of OOP. It explains the concepts well IMHO. Alan G.

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chemical formula
by Tim Wilson March 31, 1999

March 31, 1999

Thanks to everyone who offered suggestions for my little molecular weight app. You've given me more than enough to chew on for awhile. I plan to study the OOP techniques that were used in creating them and see if I can understand it. I have yet to read a good tutorial on OOP for the novice. I find _Programming Python_ to be a little too advanced for me in that area. I'm working my way through Guido's excellent tutorial as well, but even there it's easy to get lost in the vocabulary. If anyone knows of some reading I could do to get the "big picture" of OOP, please post it. Hanging loose as usual, Tim -- Timothy D. Wilson "A little song, a little dance, University of MN, chem. dept. a little seltzer down your wilson(a)chem.umn.edu pants." -Chuckles the Clown Phone: (612) 625-9828 as eulogized by Ted Baxter

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parsing chemical formula
by Tim Wilson March 31, 1999

March 31, 1999

Greetings all: I'd like to write a small Python app to act as a command line molecular weight calculator. I'm a Python beginner, and I'm still in the planning stage on this one. Specifically, I'd like to get some expert opinions on the best way to parse the chemical formula to extract the type and number of atoms. An example (and chemistry refresher): H2SO4 contains 2 H, 1 S, 4 O atoms Mg(NO3)2 contains 1 Mg, 2 N, 6 O atoms (watch those parentheses!) Ideally, the user would run the program like this: $ molwt H2O The molecular weight of H2O is 18.02 g/mol. $ I've constructed a dictionary containing all of the element symbols and molecular weights. What type of data structure would be most appropriate for temporarily holding the number and type of atoms in the formula before the total mol. weights is calculated? Any other suggestions? I think this might be a nice little app that could be very useful. -Tim (At least that's what some people call me.) -- Timothy D. Wilson "A little song, a little dance, University of MN, chem. dept. a little seltzer down your wilson(a)chem.umn.edu pants." -Chuckles the Clown Phone: (612) 625-9828 as eulogized by Ted Baxter

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Re: Listing web contents
by Jon Cosby March 29, 1999

March 29, 1999

>I'm assuming the URL points to an HTML document, and what you really >want is a listing of URLs that the given URL refers to. > >In this case, you can cook something up using Python's HTML parsing >library module (htmllib). > >I'm guessing that what you area really looking for is writing an >automated tool that browses a tree of related pages on the web. >In this case, please have a look at webchecker in the Python source >distribution, Tools/webchecker/. > Websucker may be what I'm looking for. I'm trying to write a simple search engine; can you give me a hint as to how to edit websucker to return a list of web contents, rather than downloading the whole site? Thanks, Jon Cosby

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RE: [Tutor] Re: Listing web contents
by Doug Stanfield March 29, 1999

March 29, 1999

Guido, I believe there is a need for the public tutor list. I still consider myself a novice, and probably will be for the rest of my programming days. I'm on record in c.l.py advocating a different forum for those of us without the concentration of effort or otherwise the wherewithal required to progress to guru-dom. My lack of progress is because my work keeps me from being a programmer. Yet I have problems that need to be solved programmatically. Python has taken me further with less effort than any other 'way'. I'm one of those that will be filling in the third or fourth level down on the pyramid as Python spreads further through the computing community. There is a difference between documenting something and explaining it. Also between clarifying using the jargon of programming theory or language comparisons, and teaching the fundamental or elementary use of Python. There's definately a difference between a reference 'bot and an educator. I see this as the difference between c.l.py and the tutor list. And because the tutor list is public instead of hidden it is generating that atmosphere of trusting collegial discussion that leads to the 'ah ha' reaction. Someone once told me that an educator was someone who could correctly answer a question at least three uniquely different ways. The other necessary ingredient is the empathy to know which answer most resonates with the students current understanding. Personally I feel the empathy on the tutor list, but lacking that, it's most helpful to hear all the answers and all the perspectives. For me that most often leads to a higher level of comprehension. The nature of your question implied merging the tutor-list into the anonymous private answer help system. Perhaps you meant the opposite. If there could only be one I'd choose the tutor-list, but this email should be plenty of evidence that I don't feel the need for anonymity. Others must so I'd say both forums have their place. -Doug- > -----Original Message----- > From: David Ascher [mailto:da@ski.org] > Sent: Sunday, March 28, 1999 8:03 PM > To: Guido van Rossum > Cc: tutor(a)python.org > Subject: Re: [Tutor] Re: Listing web contents > > > On Sat, 27 Mar 1999, Guido van Rossum wrote: > > > PS. To the tutors. I see no significant difference > between the tutor > > list and the help list. Perhaps tutor should be merged back into > > help? > > Well, I think there's a difference, but perhaps it's too soon > to tell. The > biggest difference IMHO is that the tutor list is public and > subscribed to > by both tutors and novices -- and my hope is that some of the novices > listening on the exchanges can learn from them, which doesn't > happen w/ > the help-list because of its relatively private nature (which > I think is > useful for some). > > Is that happening? I can't tell -- maybe some of the novices > on the list > can let us know. > > --david ascher > > > > > _______________________________________________ > Tutor maillist - Tutor(a)python.org > http://www.python.org/mailman/listinfo/tutor >

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Re: Listing web contents
by Guido van Rossum March 29, 1999

March 29, 1999

> Hi - Is there any way of listing the directory contents of a URL address? > Something like > > dir = urllib.urlopen(url) > os.listdir(dir) I'm assuming the URL points to an HTML document, and what you really want is a listing of URLs that the given URL refers to. In this case, you can cook something up using Python's HTML parsing library module (htmllib). I'm guessing that what you area really looking for is writing an automated tool that browses a tree of related pages on the web. In this case, please have a look at webchecker in the Python source distribution, Tools/webchecker/. PS. To the tutors. I see no significant difference between the tutor list and the help list. Perhaps tutor should be merged back into help? --Guido van Rossum (home page: http://www.python.org/~guido/)

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Python Snippets Site
by Hans Nowak March 27, 1999

March 27, 1999

Howdy y'all, This tutor forum looks like a good place to announce my Python Snippets site. (In fact, it's been there for a while, but I've been reluctant to show it to the world.) In this case, "snippets" are small, *working* pieces of Python code. "Working" means here that you can take a snippet, feed it to Python, and it works right out of the box, without any implicit assumptions ("it's obvious that this module should have been imported" etc). People who have a certain Python question, can go to this site and see if the solution is there. Of course, anybody who wants learn something new can browse it. Anyway, that's the goal. So far not too much snippets are in the repository yet, and those who are, might need a double check. A lot of new ones are waiting on my hard disk, but before I spend much energy to working on this site, I want to know if it will be useful to a lot of people. Here's what I offer: ;^) http://www.hvision.nl/~ivnowa/snippets/ (It's still under construction, and as I said, there aren't many snippets yet, but before I continue to work on it, I need to know if it's worth working on.) Here's what I need: 1) Feedback. It's cool making such a site, but if I don't get any reactions, I won't know if things are good or bad, useful or crockish, etc. 2) More snippets. Lots more! The more, the merrier. A site with lots of snippets is of course more likely to have the solution to one's problem. I feel that picking snippets is not something one person should do. If your question is satisfactorily answered by a Python guru, and s/he has provided you with some nice code, I'd like to hear from it. Similarly, if you've just developed and posted some great code, I'd appreciate it if you could cc me the file. Sure enough, I can find it in the newsgroup myself -- but if anyone will be so friendly to forward his code, this would speed up things a lot. Because to be honest, I don't have much time to wade through myriads of files looking for that one gem of Python code. The email address is hey_psst(a)usa.net. (PSST stands for Python Snippet Support Team. ;^) Please do not use my other email addresses for this purpose. Depending on your reactions and support, this site will live... or die. Veel liefs, + Hans Nowak (Zephyr Falcon) + Homepage (under construction): http://www.cuci.nl/~hnowak/ + You call me a masterless man. You are wrong. I am my own master. + May Grandma Moses bake your heavy burden!

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Re: super classes
by Art Siegel March 27, 1999

March 27, 1999

>What are you porting, btw? > Thanks for response. I haven't absorbed it yet but I will. Your sample code is on point because I am doing graphic stuff - mostly with David's PyOpenGL. I have also taken a few shots at using OpenGL through Java using JPython. The one Java OpenGL implementation that I got at (with David's help) was Magician. Magician was commercial, its recent versions available for download were crippled - and, even if I wanted to license it, it in fact has been abandoned by its developers. So, what I am trying to port to JPython now are demos of GL4Java - a GNU license product and what looks like a good implementation of OpenGl for Java

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Re: [Tutor] Re: super classes
by Art Siegel March 27, 1999

March 27, 1999

-----Original Message----- From: Joseph J. Strout <joe(a)strout.net> To: Art Siegel <ajs(a)ix.netcom.com>; Python Tutor <tutor(a)python.org> Date: Saturday, March 27, 1999 11:03 AM Subject: Re: [Tutor] Re: super classes >A superclass is the parent of some other class, i.e., the class from which >it is derived. Now that I understand the terminology, a few more questions: Java has a "super" function, I believe, which I assume allows one to directly access methods of the parent class from inside the child class. Under what circumstances is it useful? Aren't, by definition, the parent's method already at the disposal of the child? What is the Python equivalent to the java super call? This is all coming up as I try to understand some java code and port it to Python.

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