Mailman 3 July 2003 - Edu-sig

re: A small essay in my own defense
by Arthur July 9, 2003

July 9, 2003

>To me, the question than becomes one of semantics. >How far down the road toward a redefinition of the >word "programming" are we allowing ourselves to go Which is also, I think, related to a sense of responsibility to a larger community - where I guess my first loyalties lie. I have no interest in provoking, for example, the DrScheme people to murder by competing with their substantial efforts by playing with semantics. As we are defining "programming", is the claim made on the edu-sig page that CP4E is simply a different approach to accomplishing what the DrScheme folks are trying to accomplish, defensible. I have substantial doubt.. So I wonder how the DrScheme folks might feel. As far as I am concnerned, the DrScheme folks have shown great restraint. I would hate to have to "go back to Russia" myself, and defend them, should they decide to no longer hold their fire. Art

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Re: [Edu-sig] Re: Student teaching and tutorials
by Lee Harr July 9, 2003

July 9, 2003

>>This is my book that is based on pygame: >> >>http://staff.easthighschool.net/lee/computers/book/ >> >Looks very interesting! >BTW: yesterday (no joke!) I discovered, that ther is a function >hypot(x,y) in module math. Maybe helpful for young students ;-) > Good point. I found about 10 places in my code where I had used sqrt() instead. >Do you think it would be easy to implement the >mini - Lsystem - example (posted 12 hours ago) using pygsear >(instead of my extended turtle.py) ? > I just made a new version (http://savannah.nongnu.org/files/?group=pygsear) which includes translations of your code. I cannot guarantee it does exactly the same thing it did before, but it does something interesting :o) Here is an excerpt from examples/penguin.py : def cellular(self, code="04444333221", cellsize=4): """Adapted from code posted to edu-sig(a)python.org by Gregor Lindl""" w, h = conf.WINSIZE cols = w/cellsize lines = h/cellsize code = code[:13] # What does the 13 mean? code = code + "0"*(13-len(code)) world = [] topline = [0]*cols topline[cols/2] = 1 for z in range(lines): world.append(topline) newline = [0]*cols for s in range(1, cols-1): sum = topline[s-1] + topline[s] + topline[s+1] newline[s] = int(code[sum]) topline = newline for y in range(lines): for x in range(cols): color = COLORS[world[y][x]] self.moveTo((x*cellsize, y*cellsize)) self.square(cellsize, color=color, width=0) def lindenmayer(self, axiom="F", regulator={"F":"FF+[+F-F-F]-[-F+F+F]"}, deep=3, walked=9, angle=180/8.0, startpos=None, startdeg=None): """Adapted from code posted to edu-sig(a)python.org by Gregor Lindl""" self.tstack = [] def l(angle=angle): self.left(angle) def r(angle=angle): self.right(angle) def turn(): self.left(180) def f(n=walked): self.penUp() self.forward(n) def F(n=walked): self.penDown() self.forward(n) def save(): self.tstack.append((self.getPosition(), self.getDeg())) def load(): position, deg = self.tstack.pop() self.moveTo(position) self.turnTo(deg) regulate = {"-":l, "+":r, "F": F, "f":f, "|": turn, "[":save, "]":load} def replace(follow, regulator, n): for i in range(n): newfollow = "" for element in follow: newfollow = newfollow + regulator.get(element, element) follow = newfollow return follow if startpos is not None: self.moveTo(startpos) if startdeg is not None: self.turnTo(startdeg) self.step, self.angle = walked, angle design = replace(axiom, regulator, deep) for b in design: try: regulate[b]() except KeyError: pass _________________________________________________________________ Add photos to your e-mail with MSN 8. Get 2 months FREE*. http://join.msn.com/?page=features/featuredemail

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Re: Student teaching and tutorials
by Arthur July 9, 2003

July 9, 2003

>What the greatest teaching tool ever for me would a >python tutorial on how to build a message board/forum. I strongly suspect that such a tutorials already exists. In the form of working programs, which you can take apart, and analyze, and break, and then fix, and change, and break again, and fix again. But it might be necessary to be a bit patient, and take a step at a time. Understanding some of the basics of networking (I don't) before you try to go on to something more full blown, like a message board. I second Lee's recommendation that his book and his pygear software might be a good place to start. http://staff.easthighschool.net/lee/computers/book/ I do know that at least one of his demos show how to make a pygame game into a multi-player network game, with Twisted. Appropriate, because Twisted, which started by younger folks developing a multi-player gaming environment in Python, has become an extremely important and visible Python project. Please *don't* wait for someone to write the precise tutorial you might have in mind. Everything you need to know is out there. If you are willing to learn how to learn - using the work many people have generously made available on the Internet, for free, and with nothing hidden from view. Lee tells it to you straight. <quote> """It is my belief that the only way to know what a computer can do, and what you can make a computer do, is to try to make the computer do what you want it to do. In other words: You cannot learn to program by reading a book. You must write code. Lots of code. As you read this book, keep that in mind. Try the examples, certainly, but if the examples or the text inspires an idea of your own, by all means work on that for a while. The book will be here. You can always come back and pick up where you were. Play, have fun, see what you can do, then come back and read some more. It is the best way to learn.""" </quote> The only step further that I can imagine from Lee's approach, is a book focused as a tutorial on using Open Source resources in learning to program. Learning how to learn, circa 2003. Good idea, Art. Art

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Re: Student teaching and tutorials
by Lee Harr July 8, 2003

July 8, 2003

>Web development and game development are the two things held in >regard by students. I would also love an easier tutorial for total >beginners branching off pygame. >As a last >note, I find many tutorials helpful, but something they all lack is a >test or review at the end. This is my book that is based on pygame: http://staff.easthighschool.net/lee/computers/book/ Each section has a set of exercises, and the exercises have quiz-like questions in order to get in and see my solutions. Let me know if this helps... My plan is to extend the book to web-programming (with zope and/or twisted) and gui programming (pyqt/pygtk/etc) but I have not had much feedback, so I have kind of slowed down. _________________________________________________________________ MSN 8 with e-mail virus protection service: 2 months FREE* http://join.msn.com/?page=features/virus

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A small essay in my own defense
by Arthur July 8, 2003

July 8, 2003

A small essay in my own defense. problem 1. I don't believe in CP4E. Because "everyone" ain't interested or capable. Why be coercive and unrealistic - out of the box? CP4E is, to me, just a marketing slogan and IMO, a poorly chosen one. problem 2. I insist that I should not feel inhibited in stating problem 1, as I have. On principal. problem 3. I have no interest, stand-alone, as to the user count of Python in the school systems. I get no royalties. problem 4. I am incredibly enthusiastic about the possiblities for the use of Python as a catalyst for some changes in the way things are taught. It is those changes that interest me, primarily, not the Python head count. problem 5. Any expectation that discussions can be had about education, in general, and education and technology in particular, circa 2003, clean of "politics" is an unrealistic expectation. And its own form of politics. problem 6. I am glad Python is not Rebol, and hope (and am confident) it will remain not so.. Art

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re: A small essay in my own defense
by Arthur July 8, 2003

July 8, 2003

Kirby writes - >As to head count, to me it seems an inevitable megatrend that Python will continue to grow in popularity. I agree. And my track record is not bad. In an early converstaion with the managing partner of a firm I joined - earliesh 1990's - I brought up Linux. He asked me how much it costs. $0. He found it hard to take me seriously after that. And with Managing Partners, one never seems to get the last laugh - under any circumstances. I consider myself a good community member, not a bad one. In Guido's Euro-Python lecture, which I just read, he talks about his continuing interest in CP4E - mentions PyGame and a Python clone of Karel the Robot, dubbed "Guido the Robot" - whether that is the working name, or Guido was just being tongue in cheek - I don't know. As long as Python is under the radar, its under the radar. Which might not be forever. And what goes in a freewheeling community of iconoclasts, might not make it at Community School Board 6. I hope that "Guido the Robot" ends up as wonderful educational software. And dearly hope it is called something else. And maybe we should keep our clothes on, next time the opportunity for the cover of L:inux Journal comes up. Beyond boys with toys, I hope. Art

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PEPTALK: path sanity and newbie mental health -- please help
by Jason Cunliffe July 8, 2003

July 8, 2003

Greetings I've been away from Python for while and now diving back, hoping to experiment with Leo and Jabber over the summer... *Context* I am humiliated and feel like moron. I am getting stuck [again] on my most basic eternal Python newbie issue: paths and module import. I must be missing something. I consult some excellent books, then googled further into it, but found I was taken on a pythonesque journey which did not help either. However I met trails of others experiencing similar confusion. I imagine Python teachers and students must have dealt with this satisfactorily gazillion times, but still am compelled to think there must be a better simpler way. I'd really appreciate your help and feedback on my suggestions. Hopefully this will end up as a PEP which makes life easier for all, especially beginners. btw, I tend to agree with Kirby's recent comment: "What does or doesn't make sense to the newbie is irrelevant. A language need not be designed based on that perspective, to be good. It's the job of teachers to smooth the on ramp." But I 'd add to that configuration and preferences *are* the universal 'on-ramp' and need to be designed with beginners in mind as well as advanced professionals. I believe those two goals cannot be satisfied in one simple consistent solution. Python fails at present to achieve this IMHO, [especially for Windows users]. And I sincerely apologize in advance if I've missed the instructions which clearly address these issues. I'll present my problem as narrative based around a set of IDLE sessions. This only very slightly contrived example, and I am not really exaggerating. First Freshly install Python on Win32. Now download and install some modules and packages I want to explore.. Python 2.2.2 (#37, Oct 14 2002, 17:02:34) [MSC 32 bit (Intel)] on win32 Type "copyright", "credits" or "license" for more information. IDLE 0.8 -- press F1 for help PROBLEM #1 Where to install things on Python and how to access them? It seems recommended default is to install modules and packages into Lib/site-packages/some-sub-folder. PROBLEM#2 But what about my personal work? I can find precious little advice on that.. . One of the first things all beginners are taught do is save a "helloworld.py" file. It is good practice for all software to keep user files separate from system or application files. Better for sysadmin, maintenance and collaborative workflow. But, in Python at present the first problem is that creating a personal folder for scripts outside of the application installation which is visible to import statements >>> import jabber Traceback (most recent call last): File "<pyshell#1>", line 1, in ? import jabber ImportError: No module named jabber >>> hmm.. go study a bit. ok it seems 'jabber' is not yet on the PYTHONPATH. Q: How to see PYTHONPATH? >>> PYTHONPATH Traceback (most recent call last): File "<pyshell#2>", line 1, in ? PYTHONPATH NameError: name 'PYTHONPATH' is not defined >>> $PYTHONPATH SyntaxError: invalid syntax >>> nope :-(( Since PYTHONPATH is so essential to using Python, surely it would make sense to make that permanently available to people? To my mind an intuitive interface would allow direct typing any of the environment variables in idle shell. Guess it's time to study up some more. Aha! -- sys.path >>> sys.path Traceback (most recent call last): File "<pyshell#4>", line 1, in ? sys.path NameError: name 'sys' is not defined jeez :-( study up some more >>> import sys >>> sys.path ['C:\\PYTHON22\\Tools\\idle', 'M:\\jasonic\\python', 'C:\\Python22', 'C:\\PYTHON22\\DLLs', 'C:\\PYTHON22\\lib', 'C:\\PYTHON22\\lib\\lib-tk', 'C:\\PYTHON22\\lib\\site-packages'] aah much better.. But still counter-intuitive imho. If "sys.path" is so essential, then why do I have to import sys all the time? And why do so many texts talk about PYTHONPATH when what they really mean is sys.path? And how do I customize my environment so I don't have to jump through these hoops every time? Meanwhile my study has shown I must add jabber to sys.path. ok >>> sys.path.append('C:\\PYTHON22\\lib\\site-packages\\jabber') >>> import jabber >>> jabber <module 'jabber' from 'C:\PYTHON22\lib\site-packages\jabber\jabber.pyc'> >>> Yay! success :-) Now I can follow the jabber examples from my book for a while.... I take a break and shutdown, but when I launch IDLE on my return, trouble in paradise again: >>> import jabber Traceback (most recent call last): File "<pyshell#0>", line 1, in ? import jabber ImportError: No module named jabber >>> arghh.. ok guess gotta go through all that again [hope I can remember]: >>> sys.path.append('C:\\PYTHON22\\lib\\site-packages\\jabber') >>> import jabber >>> jabber <module 'jabber' from 'C:\PYTHON22\lib\site-packages\jabber\jabber.pyc'> OK yes not such a big deal. But how to add jabber or any module permanently to the path.? I study this but find I am getting more confused... Several options are suggested : a) Run regedit and add jabber to the path entries buried there deep. I don't like this. It feels way too far removed from python. Surely there is some way not to have to mess with regedit.exe? Why isn't there a simple config preferences file I can edit like just about every other software I use? b) edit autoexec.bat and create a PYTHONPATH entry and then add 'jabber' to that. Yikes this seems also too far from python. It uses a syntax I am not certain about. I look in books and google around, but honestly it's hard to find just some simple example I can copy. Autoexec.bat can't even use full pathnames and its is buried like regedit until I learn I can enter 'sysedit' in the Start/Run menu as nice shortcut. Besides, I thought Python was cross-platform and here I am messing with to much windows-specific crap, [ahem] sorry "configuration details". To make matters worse, I learn that apparently Python on windows uses the registry, but IF a PYTHONPATH definition also exists in autoexec.bat, then it will insert those values also so they show up *combined* in Python when I call sys.path yeow :-(( Frankly this seems totally nuts to me. There appears to be no single common place/file where I can keep track of path entries and edit them quickly. Why the hell not? It may not be in essence Python's fault, but surely ther is a better simpler way in 2003? Windows is still the major OS in use globally. Maybe 5-10 years later Linux will be. hmm... I learn from Google search and more book reading that there are some neat ways to customize and streamline Python on my system. c) One advises that I can create a file with .pth suffix. Sounds good, and to be very honest I now remember that eons ago, that is how I did successfully customize my Python installation.Alas I can';t remember and ma having devils own time to track down the crucial steps to do this. Unfortunately hard to find actual any examples on .pth files. Also it too seems to depend upon successful use of PYTHONPATH and I want to get to the heart of the matter. d) I find some references to site.py and something promising called "sitecustomize.py" I try these but no luck. I feel like an idiot and am getting angry and frustrated. I imagine what really would make sense to me and decide to post to Edu-Sig for help. *Dream Solution [DS]* DS #0 -- Display PYTHONPATH when Python boots. Make this a default, which pros can disable via config value. Python 2.2.2 (#37, Oct 14 2002, 17:02:34) [MSC 32 bit (Intel)] on win32 Type "copyright", "credits" or "license" for more information. IDLE 0.8 -- press F1 for help ['C:\\PYTHON22\\Tools\\idle', 'M:\\jasonic\\python', 'C:\\Python22', 'C:\\PYTHON22\\DLLs', 'C:\\PYTHON22\\lib', 'C:\\PYTHON22\\lib\\lib-tk', 'C:\\PYTHON22\\lib\\site-packages'] or like this: Python 2.2.2 (#37, Oct 14 2002, 17:02:34) [MSC 32 bit (Intel)] on win32 Type "copyright", "credits", "license" or "paths" for more information. <<<< What do you think about this ? IDLE 0.8 -- press F1 for help DS #1 -- To be able to enter environment variables directly like this anytime: >>> PYTHONPATH ['C:\\PYTHON22\\Tools\\idle', 'M:\\jasonic\\python', 'C:\\Python22', 'C:\\PYTHON22\\DLLs', 'C:\\PYTHON22\\lib', 'C:\\PYTHON22\\lib\\lib-tk', 'C:\\PYTHON22\\lib\\site-packages'] DS #2 -- To be able to add to that by setting like this: PYTHONPATH = ['C:\\PYTHON22\\Tools\\idle', 'M:\\jasonic\\python', 'C:\\Python22', 'C:\\PYTHON22\\DLLs', 'C:\\PYTHON22\\lib', 'C:\\PYTHON22\\lib\\lib-tk', 'C:\\PYTHON22\\lib\\site-packages', 'C:\\PYTHON22\\lib\\site-packages\\jabber'] <<< the last entry is my addition or by adding or appending: PYTHONPATH.add('C:\\PYTHON22\\lib\\site-packages\\jabber') PYTHONPATH.append('C:\\PYTHON22\\lib\\site-packages\\jabber') You'll may say "Jason, that's not the Python Way to do it. You must be initiated." And I reply, "Ok, but fucking around with autoexec.bat and regedit sure ain't the Python Way either... I've been at this for years, and still tis nuts and that's why I am writing this long edu-sig post. Show me please!" But I concede to learn and follow the sys.path syntax though I still feel very strongly that there *should* also be a more direct aliasing between environment variables outside of Python and how they are called inside Python. Else needs to be much better explained. Just look at most books on Python and you might se what I mean. Most are excellent but I suspect are written by experienced programmers long familiar with handling *nix type environment variables. DS #3 SAVE and LOAD paths Ok this is what I am really proposing: sys.path.save() sys.path.load() These would both default to use a clear single file called "PYTHONPATH.py" created at installation. My point is that people could easily set or get their own and switch on fly like this: sys.path.save('mypathfile.py') sys.path.load('mypathfile.py') where "mypathfile.py" contains a entry such as: PYTHONPATH = ['C:\\PYTHON22\\Tools\\idle', 'M:\\jasonic\\python', 'C:\\Python22', 'C:\\PYTHON22\\DLLs', 'C:\\PYTHON22\\lib', 'C:\\PYTHON22\\lib\\lib-tk', 'C:\\PYTHON22\\lib\\site-packages', 'C:\\PYTHON22\\lib\\site-packages\\jabber'] So in a given session I might do this: >>> sys.path.append('M:\\jasonic\\python') >>> sys.path.save() And I propose the same syntax and approach should work for all the variables in the same way across platforms. All that remains is how best to display or set them all ? I found something which looks close: os.environ["ORACLE_HOME"]="/opt/app/ora/" http://www.faqts.com/knowledge_base/view.phtml/aid/3298/fid/245 I imagine running python and seeing something this Python 2.2.2 (#37, Oct 14 2002, 17:02:34) [MSC 32 bit (Intel)] on win32 Type "copyright", "credits", "license", or "paths" for more information. IDLE 0.8 -- press F1 for help >>> paths PYTHONPATH loaded from ''C:\\python22\PTYHONPATH.py" PYTHONSTARTUP loaded from "M:\\jasonic\\python\\mystartup.py" etc.. Ideally there is a single dict which holds all of these and can be easily viewed and edited anytime on any system the same way and will always be accessible in the Python shell. Perhaps there already is and I'm too dumb to have found it. *Books* Before writing this, last night along with docs and Google research I went to my Python shelf and pulled down the following: - Python Essential Reference by David M. Beazley - The Quick Python Book by Darryl Harms and Kenneth Mcdonald - Python Programming on Win32 by Mark Hammond and Andy Robinson - Core Python Programming by Wesley Chun - Python Cookbook edited by Alex Martelli and David Ascher - Python In A Nutshell by Alex Martelli *Personal* I realize that my main problem is I have a bad memory, especially for things which are counter-intuitive to me. Typically caused by switching between many different systems or like now when I am not daily working with it. I recognize this as a weakness. But also on occasion it is a strength, because motivates to find a better/simpler design. thanks for any help Jason ______________________________________________ Jason Cunliffe [NOMADICS: Director art+design] Tel/fax: +1 718 422-1078 jasonic(a)nomadics.org N 43:00.000' W 074:31.875' ALT:1144 ft 84 Henry Street #3C Brooklyn NY 11201 USA http://tranzilla.net/.v

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[Fwd: Re: [Edu-sig] Would a simplified Python UI for MiddleSchool students be worth the effort?]
by Gregor Lingl July 8, 2003

July 8, 2003

Kirby Urner schrieb: > At 12:23 PM 7/7/2003 -0700, you wrote: > >> routines running! Sure, there are some kids that can abstract things >> and get >> all excited about rearranging letters and numbers, etc. But a lot of >> people >> in general like the visual pleasure of seeing things work. *sigh* > > > Some kids even like both! (and some neither :-( -- sigh again). > ... > > So whereas I'm all for flashy visuals, a well-rounded diet should > include some regular expressions and such, IMO (but not exclusively > -- turtle graphics with Tkinter, yes! (including the demo). And > Kevin implemented some turtle stuff in PythonCard that's pretty > nifty as well). Could this be part of your well-roundet diet? (Aims at visualizing some fundamental concepts of computer-science) ################################ # Mini Lindenmayer tool ############################### from __future__ import generators from turtle import Pen def ersetze( folge, ersetzungsregeln, n ): for i in range(n): neuefolge = "" for element in folge: neuefolge = neuefolge + ersetzungsregeln.get(element,element) folge = neuefolge return folge def lindenmayer(turtle, axiom = "", ersetzungsregeln = {}, tiefe = 1, schritt = 5, winkel = 90, startpos = (0,-120), startdir = 90, updating = 20): turtle.step, turtle.angle = schritt, winkel zeichnung = ersetze(axiom, ersetzungsregeln, tiefe) turtle.start(startpos, startdir) return turtle.zeichne(zeichnung, turtle.standardregeln(), updating) class LPen(Pen): def __init__(self): Pen.__init__(self) self.tstack = [] def start(self, startpos, startdir): self.up() self.goto(startpos) self.left(startdir) self.down() self.tracer(1) self.tracer(0) def zeichne( self, befehle, regeln, updating ): i = 0 for b in befehle: try: regeln[b]() except: pass i += 1 if i % updating == 0: self.tracer(1) self.tracer(0) # Wir machen draus einen Generator! yield 1 ################################ # Standardregeln ################################ def r(self): self.right(self.angle) def l(self): self.left(self.angle) def f(self): self.up() self.forward(self.step) def F(self): self.down() self.forward(self.step) def turn(self): self.left(180) def save(self): self.tstack.append( (self.pos(), self.heading()) ) def load(self): position, richtung = self.tstack.pop() self.up() self.goto(position) self.setheading(richtung) def standardregeln(self): return {"-":self.l, "+":self.r, "F": self.F, "f":self.f, "|": self.turn, "[":self.save, "]":self.load} # 2 examples for Lindenmayer plants: kraut = { "axiom" : "G", "ersetzungsregeln" : { "G" : "GFX[+G][-G]", "X" : "X[-FFF][+FFF]FX" }, "tiefe" : 5, "schritt" : 4.5, "winkel" : 180.0/7, "startpos" : (-90, -128), "startdir" : 90 } busch = { "axiom" : "F", "ersetzungsregeln" : { "F" : "FF+[+F-F-F]-[-F+F+F]" }, "tiefe" : 3, "schritt" : 9, "winkel" : 180.0/8, "startpos" : (60, -128), "startdir" : 90, "updating" : 20 } l1, l2 = lindenmayer(LPen(), **kraut), lindenmayer(LPen(), **busch) done = 0 while done < 2: done = 0 for l in l1, l2: try: l.next() except: done += 1 raw_input() > > And lets not forget the cellular automata (perhaps a bridge between > text and graphics, as simple CA may be displayed using a kind of > 'ascii art' -- see below). Or this: from Tkinter import Tk, Canvas, mainloop from Canvas import Rectangle class ZACanvas(Canvas): def __init__(self, root, NX=59, NY=40, feldbreite=4): self.NX, self.NY = NX, NY w,h = NX*feldbreite, NY*feldbreite Canvas.__init__(self, root, width = w+1, height = h+1, bg = "yellow") self.pack() self.farbe = ["white", "red", "green", "blue", "yellow"] self.gitter = {} for spalte in range(NX): for zeile in range(NY): x0 = 2 + spalte * feldbreite y0 = 2 + zeile * feldbreite x1 = x0 + feldbreite y1 = y0 + feldbreite r = Rectangle(self, x0, y0, x1, y1, fill="black", outline="black") self.gitter[(spalte,zeile)] = r def set(self,feld,farbe): self.gitter[feld]['fill'] = farbe self.gitter[feld]['outline'] = farbe def draw(self,welt): for y in range(self.NY): for x in range(self.NX): self.set((x,y), self.farbe[welt[y][x]]) self.update() def ZA(code, spalten = 59, zeilen = 40): code = code[:13] code = code + "0"*(13-len(code)) welt = [] altezeile = [0]*spalten altezeile[spalten//2] = 1 for z in range(0,zeilen): welt.append(altezeile) neuezeile = [0]*spalten for s in range(1,spalten-1): summe = altezeile[s-1]+altezeile[s]+altezeile[s+1] neuezeile[s] = int(code[summe]) altezeile = neuezeile return welt ZACanvas(Tk()).draw(ZA("0211021")) mainloop() If necessary, ZACanvas-class could be supplied by the teacher. Remark: (Easy) implementation in wxPython, will result in faster graphics. (Code for both examples attached, for your convenience) Gregor ################################ # Mini Lindenmayer tool ############################### from __future__ import generators from turtle import Pen def ersetze( folge, ersetzungsregeln, n ): for i in range(n): neuefolge = "" for element in folge: neuefolge = neuefolge + ersetzungsregeln.get(element,element) folge = neuefolge return folge def lindenmayer(turtle, axiom = "", ersetzungsregeln = {}, tiefe = 1, schritt = 5, winkel = 90, startpos = (0,-120), startdir = 90, updating = 20): turtle.step, turtle.angle = schritt, winkel zeichnung = ersetze(axiom, ersetzungsregeln, tiefe) turtle.start(startpos, startdir) return turtle.zeichne(zeichnung, turtle.standardregeln(), updating) class LPen(Pen): def __init__(self): Pen.__init__(self) self.tstack = [] def start(self, startpos, startdir): self.up() self.goto(startpos) self.left(startdir) self.down() self.tracer(1) self.tracer(0) def zeichne( self, befehle, regeln, updating ): i = 0 for b in befehle: try: regeln[b]() except: pass i += 1 if i % updating == 0: self.tracer(1) self.tracer(0) # Wir machen draus einen Generator! yield 1 ################################ # Standardregeln ################################ def r(self): self.right(self.angle) def l(self): self.left(self.angle) def f(self): self.up() self.forward(self.step) def F(self): self.down() self.forward(self.step) def turn(self): self.left(180) def save(self): self.tstack.append( (self.pos(), self.heading()) ) def load(self): position, richtung = self.tstack.pop() self.up() self.goto(position) self.setheading(richtung) def standardregeln(self): return {"-":self.l, "+":self.r, "F": self.F, "f":self.f, "|": self.turn, "[":self.save, "]":self.load} # 2 examples for Lindenmayer plants: kraut = { "axiom" : "G", "ersetzungsregeln" : { "G" : "GFX[+G][-G]", "X" : "X[-FFF][+FFF]FX" }, "tiefe" : 5, "schritt" : 4.5, "winkel" : 180.0/7, "startpos" : (-90, -128), "startdir" : 90 } busch = { "axiom" : "F", "ersetzungsregeln" : { "F" : "FF+[+F-F-F]-[-F+F+F]" }, "tiefe" : 3, "schritt" : 9, "winkel" : 180.0/8, "startpos" : (60, -128), "startdir" : 90, "updating" : 20 } l1, l2 = lindenmayer(LPen(), **kraut), lindenmayer(LPen(), **busch) done = 0 while done < 2: done = 0 for l in l1, l2: try: l.next() except: done += 1 raw_input() from Tkinter import Tk, Canvas, mainloop from Canvas import Rectangle class ZACanvas(Canvas): def __init__(self, root, NX=59, NY=40, feldbreite=4): self.NX, self.NY = NX, NY w,h = NX*feldbreite, NY*feldbreite Canvas.__init__(self, root, width = w+1, height = h+1, bg = "yellow") self.pack() self.farbe = ["white", "red", "green", "blue", "yellow"] self.gitter = {} for spalte in range(NX): for zeile in range(NY): x0 = 2 + spalte * feldbreite y0 = 2 + zeile * feldbreite x1 = x0 + feldbreite y1 = y0 + feldbreite r = Rectangle(self, x0, y0, x1, y1, fill="black", outline="black") self.gitter[(spalte,zeile)] = r def set(self,feld,farbe): self.gitter[feld]['fill'] = farbe self.gitter[feld]['outline'] = farbe def draw(self,welt): for y in range(self.NY): for x in range(self.NX): self.set((x,y), self.farbe[welt[y][x]]) self.update() def ZA(code, spalten = 59, zeilen = 40): code = code[:13] code = code + "0"*(13-len(code)) welt = [] altezeile = [0]*spalten altezeile[spalten//2] = 1 for z in range(0,zeilen): welt.append(altezeile) neuezeile = [0]*spalten for s in range(1,spalten-1): summe = altezeile[s-1]+altezeile[s]+altezeile[s+1] neuezeile[s] = int(code[summe]) altezeile = neuezeile return welt ZACanvas(Tk()).draw(ZA("0211021")) mainloop()

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Re: Would a simplified Python UI for MiddleSchool students
by Lee Harr July 8, 2003

July 8, 2003

>Of course, the absolute basics necessary for turtle graphics leave >me torn. You might want to look at pygsear (http://www.nongnu.org/pygsear/) which is built on python and pygame. It is more intended to get kids interested in programming by having them create games, but one of the first things I made was a turtle graphics module (actually, it's a penguin ;o) Look in examples. There is no gui yet, but I have been thinking about adding one.... >but to what extent would it obscure the objectofied beauty of the >language? I'd say no more so than printing out "hello world" or your name or other strange t3xt tricks. Should we forsake output altogether? :o) _________________________________________________________________ Help STOP SPAM with the new MSN 8 and get 2 months FREE* http://join.msn.com/?page=features/junkmail

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Path sanity?
by ajsiegel＠optonline.net July 7, 2003

July 7, 2003

Jason - I have reread your posts, and - guess what - I object. In tone, and content. >From the title, onward. Path sanilty, implying that the status quo is path insanity. Harsh. And a very, very premature judgment, IMO. What the responses to your post prove, to me, is there are multiple possible strategies for the solution to the problem you perceive. To the extent there really is a problem at all. Frankly, I still don't understand truly what it is. The current directory is effectively on sys.path. One can always import pitoeey.py from a script in that same directory, without touching anything. Why doesn't that handle the cases that a newbie might be concerned with. Why would directory structures be coming into play before one learned how to handle directory structures for modules. Which, of course, can be handled in ways that are not insane, by a long measure. I think the idea/trick for having IDLE start up in your current working directory was a good one, and solves the issue where you want to simply import from that directory in an interactive session. All simple cases seemed to be covered, fairly well out of the box. And complex cases are solved by understanding the tool and the options it provides at the level appropriate for someone creating complex cases. And as long as any 3rd party library is properly installed, it will also be available. There is a good tool to help both the developer and user make sure that is accomplished - if used according to the instruction on *its* box. And, as mentioned, with the facilities of disutils, there is no good reason that a self installing executable for Windows would not be an option. Unless the distributor chooses not to make it an option. Perhaps out of conscious lack of concern for the user working on Windows. Which, of course, is her perogative. Seems that is the Jabber case. There is almost an assumption that it is being installled on *nix. And, BTW, please stop holding Rebol up to us, me. Its help system is as it should be, as is its installation procedure. The problem that Python does not meet your expectations of behaving like Rebol is, IMO,your problem. Not Python's. Good back to Russia ;) Art Art

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