Mailman 3 February 2013 - Edu-sig

a short essay about programming
by kirby urner Dec. 8, 2022

Dec. 8, 2022

A common "error" (not too serious) that I see in beginning Python (and no doubt other languages, but Python is the one I'm teaching), is having a while condition that appears to put a lid on things, but then the flow all leaks away through break statements, such that the "front door" condition is never revisited. while guess != secret: guess = int(input("Guess?: ") if guess == secret: print("You guessed it!") break else: print("Nope, try again...") What's messed up about the above code is you never really go back to the top in the case where you'd get to leave. Rather, you exit by the back door, through break. So in that case, wouldn't have been simpler and more elegant, even more "correct" (dare I say it) to have gone: while True: # no ifs ands or buts guess = int(input("Guess?: ") if guess == secret: print("You guessed it!") break else: print("Nope, try again...") I see lots of heads nodding, and that could be the end of the matter, but then a next question arises: wouldn't this also be a more correct solution?: while guess != secret: guess = int(input("Guess?: ") if guess == secret: print("You guessed it!") continue # instead of break else: print("Nope, try again...") We're back to having a variable while condition, not a boolean constant, but this time we actually exit by means of it, thanks to continue or... while guess != secret: guess = int(input("Guess?: ") if guess == secret: print("You guessed it!") else: print("Nope, try again...") ... thanks to no continue. This last one is getting a thumbs up, but then I'd pause here and say "continue" can be easier on the eyes. It's unambiguous where it takes you, in contrast to having to scan on down the gauntlet, looking for possibly other open doors. "What happens next" should not require scanning ahead too far. Help us not to get lost. Be a civic-minded coder. I'm thinking of a programming style that advises two things: (a) if you use a while condition that's variable, that's expected to change, then your goal should be to always exit because of that, i.e. that should be your only exit point. Even if some other criterion suggests exiting, you have the option to flip that "lid" at the top, to crack that front door, and bounce the ball out. (b) which is why 'continue' is your friend. You are showing the user where your 'break' statements are, except you don't use "break" statements, as you've given a non-constant condition, and your aim is to make that your ONLY exit point. In short: never use break to exit a while loop unless your condition is while True. Instead, always flip the condition and exit through the font door. However, as soon as I make that rule I can think of good reasons to break it. The other programmers in the room are shaking their heads. Won't we lose information, needed elsewhere in the program, if we "artificially" force a True condition to False. Aren't we, in effect, lying? That concern could be addressed. Keep all the info true, just treat the "lid condition" (it "keeps a lid on it") as a flag. Go ahead and remember the user's guess. allowed = 5 tries = 1 exit = False while not exit: # no other way out guess = int(input("Guess?: ") if guess == secret: print("You guessed it!") exit = True # instead of break continue print("Nope, try again...") tries += 1 if tries == allowed: print("You've maxed out") exit = True continue I think we all understand the main issue: writing reader-friendly code, and rules for doing so. There's something comforting about approaching a while loop and knowing its not a leaky sieve, riddled with back doors, maybe even an exit( ) time bomb. But in the recursion world we want a minimum of two exits usually: when another round is called for versus when we've "hit bottom". Can we have it both ways? Conclusions: Lets not be too hasty with rules of thumb and: Lets keep the reader in mind when writing code. Just because the interpreter knows to compute the flow unambiguously, doesn't mean all ways of writing it are equally reader-friendly. What may seem a gratuitous gesture, an unnecessary flourish, may actually promote reader comprehension of your code, and that should be a goal as much as satisfying the interpreter. Kirby

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Re: [Edu-sig] RurPLE-NG is nice
by Jurgis Pralgauskis April 5, 2014

April 5, 2014

Some updates: - separated Variables Watch and Output panes, to be seen simultaneusly - implemented Breakpoints :) - beta style Todo: - let enter arbitrary watch expressions http://ftp.akl.lt/users/jurgis/python/rurple-NG053.png http://ftp.akl.lt/users/jurgis/python/rurple-ng-dz0-SplitLogVars_and_Breakp… for windows one doesn't need to install python separately, just unzip and run :) http://ftp.akl.lt/users/jurgis/python/RURPLE-NG-0.53%20%5bindependent%20exe… ps.: RurPLE-NG uses py3 unicode_literals, with_statement, division, print_function so code is generally py3 compliant. when wxpy will work well with py3 it shouldn't be too hard to port fully... >> >> just wanted to mention, >> that http://dev.lshift.net/paul/rurple/ >> is a very nice and lightweit PLE. >> >> what I like most (compared to RurPLE) are: >> 1) variables watch list (if it had breakpoints, it would rock :)

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Easy Web Environment to post pupils Python Creations
by Philip Bagge April 1, 2014

April 1, 2014

Dear Colleagues, My Y6 pupils (10-11 year olds) have been creating some simple text based linear adventures using Python. Does anyone know of a way we can play their adventures online? They are not very complicated. You can see the planning here. https://sites.google.com/site/pythoncodecouk/python-adventure Also as a new person to your forum does anyone know of an easy way to search you archives just in case someone has already answered this question. Thanks in advance for any help Phil Bagge -- Primary ICT Advanced Skills Teacher HCC Teacher & IT Manager http://code-it.co.uk

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Python for Science & Electronics experiments
by Ajith Kumar Feb. 23, 2013

Feb. 23, 2013

Hello, There exists a low cost tool, called expEYES <http://expeyes.in/>, to learn science by experiments developed in Python. Real time measurements are done in Python with the help of external hardware (also open source, available<http://expeyes.in/hardware-availability>commercially). Users manual <http://expeyes.in/sites/default/files/Documents/eyesj-a4.pdf> & programmers manua<http://expeyes.in/sites/default/files/Documents/eyesj-progman.pdf> l. Also there is a GFDLd book on Python <http://expeyes.in/python-programming>available, along with acode browser<http://expeyes.in/sites/default/files/debs/learn-by-coding-1.0.1.deb>program. Ajith -- Dr. Ajith Kumar B.P. Scientist SH Inter-University Accelerator Centre Aruna Asaf Ali Marg New Delhi 110067 www.iuac.res.in Ph: (off) 91 11 26893955 (Ext.230) (res)91 11 26897867 (mob) 91 9868150852

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jeff@elkner.net wants to follow you. Accept?
by jeff＠elkner.net Feb. 20, 2013

Feb. 20, 2013

Hi, Jeffrey Elkner wants to follow you. ****** Is Jeffrey Elkner you friend? ****** If Yes please follow the link below: http://invites.infoaxe.net/signup_e.html?fullname=&email=edu-sig@python.org… If No please follow the link below: http://invites.infoaxe.net/signup_e_no.html?fullname=&email=edu-sig@python.… Follow the link below to unsubscribe from all emails from Flipora, 440 N.Wolfe Rd MS #153, Sunnyvale, CA. 94085 http://invites.infoaxe.net/unsubscribe.jsp?email=edu-sig@python.org&iid=100…

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Python testimonial sought...
by Andre Roberge Feb. 19, 2013

Feb. 19, 2013

A few years ago (at least 5 I believe) I remember reading an account from two students who had to do a term project in their final CS year. They decided to do it in Python (which they had learned on their own) whereas everyone else was using something like C++ or Java which was taught in their department. From what I remember, they completed the required work in something like 4 weeks whereas no other student team managed to do it while working for the entire term. Does anyone remember this and, more crucially, would have a link to the original story? André

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Re: [Edu-sig] Edu-sig Digest, Vol 115, Issue 10
by Jeff Elkner Feb. 19, 2013

Feb. 19, 2013

That video is still available: http://openbookproject.net/pybiblio/pythonvideo.php On Tue, Feb 19, 2013 at 6:00 AM, <edu-sig-request(a)python.org> wrote: > Send Edu-sig mailing list submissions to > edu-sig(a)python.org > > To subscribe or unsubscribe via the World Wide Web, visit > http://mail.python.org/mailman/listinfo/edu-sig > or, via email, send a message with subject or body 'help' to > edu-sig-request(a)python.org > > You can reach the person managing the list at > edu-sig-owner(a)python.org > > When replying, please edit your Subject line so it is more specific > than "Re: Contents of Edu-sig digest..." > > > Today's Topics: > > 1. Python testimonial sought... (Andre Roberge) > 2. Quarter III, Week 3: SmartNotes, ScreenCasts and Code, oh my! > (A. Jorge Garcia) > 3. Re: Python testimonial sought... (kirby urner) > > > ---------------------------------------------------------------------- > > Message: 1 > Date: Mon, 18 Feb 2013 15:39:17 -0400 > From: Andre Roberge <andre.roberge(a)gmail.com> > To: "edu-sig(a)python.org" <edu-sig(a)python.org> > Subject: [Edu-sig] Python testimonial sought... > Message-ID: > <CAGMu_=ox-hV3=4SZBK6qYe9YJagtA9-SJmc2440nA08Z2NJDBA(a)mail.gmail.com> > Content-Type: text/plain; charset="iso-8859-1" > > A few years ago (at least 5 I believe) I remember reading an account from > two students who had to do a term project in their final CS year. They > decided to do it in Python (which they had learned on their own) whereas > everyone else was using something like C++ or Java which was taught in > their department. From what I remember, they completed the required work > in something like 4 weeks whereas no other student team managed to do it > while working for the entire term. > > Does anyone remember this and, more crucially, would have a link to the > original story? > > Andr? >

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Quarter III, Week 3: SmartNotes, ScreenCasts and Code, oh my!
by A. Jorge Garcia Feb. 18, 2013

Feb. 18, 2013

Take a look at my CSH link in the blog listed below. CSH is my Computer Science Honors (SAGE/python) class which is a prerequisite for AP Computer Science (java). In CSH we usually run SAGE, but we used pure python from the command line for the first time ever this week! http://shadowfaxrant.blogspot.com/2013/02/quarter-iii-week-3-screencasts.ht… It's nothing too advanced. We're doing Binary Arithmetic, Boolean Logic, propositions, predicates and conditional statements right now. We wrote RockPaperScissors in SAGE automated with random choices for each player. We could not see a way to make it interactive in SAGE so the user could input choices and play against the computer, so we went with the CLI. In fact, I have a link on the CSH blog from programr.com so you can actually run the program yourself within the blog! You may also find my CIS(theta) link interesting. CIS is my Computing Independent Study class where we are using mpi4py on a Linux Cluster! Enjoy, A. Jorge Garcia Applied Math, Physics and CS http://shadowfaxrant.blogspot.com http://www.youtube.com/calcpage2009

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New CopyrightX StackExchange Community (off-topic?)
by Kevin Feb. 17, 2013

Feb. 17, 2013

Hi All, For anyone that sees this post as off-topic, I offer my apologies, but I kind-of feel like the subject of copyright is relevant to pretty much everything on The Internet, and especially germane to programming and education, so after thinking about it, I decided to post here. I'm one of 500 students from all over the world enrolled in a free Harvard Law School class taught through the auspices of the edX.org initiative. I feel very lucky to be participating in this course, and I've learned more about copyright in the last 3 weeks than in the previous 10 years I think. Amazing course! I've become so enthusiastic about the course and the subject that I'm trying to raise awareness about a StackExchange.com (SE) community that I just proposed yesterday and that I hope will ultimately attract many of my fellow students and other interested people from all over the world. I may be suffering from a bit of naivety, but I'm optimistic that this CopyrightX SE community might someday evolve to be a serious influence on copyright reform throughout the world. If anyone is interested, please consider following the community on SE by going here: <http://area51.stackexchange.com/proposals/51342/copyrightx?referrer=eTg5F3m…> and clicking the orange "Follow It!" button. Maybe even contribute a few example questions. Thanks and again, my apologies to anyone who perceives this as spam. -Kevin

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Overview to students re Python & GUIs: open to improvement
by Kirby Urner Feb. 15, 2013

Feb. 15, 2013

Below is some "big picture" text I plan to use in my cut and paste in my comments back to a student after they pass one of our GUI projects, all Tk endeavors. I just cobbled it together today in fact. If any edu-sig subscriber sees aspects to which I am apparently blind and should mention, I'd be happy to write a next draft with more comprehensive overview. My goal is to provide some background. We only have three GUI projects (all in Tk) and then move on. I want students to appreciate the wider world in which they've but dabbled (of course any given student may have an extensive background in GUI stuff for all I know, this is not CS0 or CS1 in that we get people with decades of coding experience, just wanting to pick up Python as another tool in their tool belt). Kirby Urner O'Reilly School of Technology ==== Note that Python-the-language stays reasonably small in that GUI stuff is relegated to 3rd party libraries, with the exception of the bundled Tk, which we're using. The core language does not concern itself with any one particular widgets solution (in contrast, some languages incorporate widgets and are not easily used with anything 3rd party). There's also a nifty turtle module for doing turtle graphics implemented in Tk, as a part of the standard library. I encourage you to check it out. John Zelle is one of the authors (not an O'Reilly author) who exploits Tk in his introduction to Python courses. I've seen air traffic control system written in Python with a Tk canvas to show airplane position. All of which is to say: Tk, the library, is a really nice cross-platform GUI toolkit, but you are not limited to that, even in open source / free world. If GUI coding is your thing, make sure to check out (or read up on): wxPython, GTK+ and QT. In addition, Jython, the version of Python implemented in Java, gives you access to everything Java has. win32all extension library lets you tap in to native Windows GUI objects. IronPython, implemented in C#, gives you access to whatever your .NET or Mono platform has in store. In other words, Python-the-language is able to control a large and growing number of GUI widget libraries. Tk is a great example of one of them and in learning to control Tk, you're getting a taste of GUI event driven programming in general. I should add that a lot of GUI stuff is these days handled in the browser if possible, i.e you need to count HTML/CSS + JavaScript as a GUI layer. In that case. Python is typically server-side, updating JavaScript via JSON, but not directly in control of your widgets.

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