Mailman 3 March 2017 - Edu-sig

a short essay about programming
by kirby urner 08 Dec '22

08 Dec '22

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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MineCraft with Python
by Jurgis Pralgauskis 04 Dec '22

04 Dec '22

Hi, intro: many kids like MineCraft :) probably you know/heared of MineCraft Pi https://www.raspberrypi.org/learning/getting-started-with-minecraft-pi/ But there seems to be Py for real MC http://coderdojotc.readthedocs.io/projects/python-minecraft/en/latest/ http://www.instructables.com/id/Python-coding-for-Minecraft/ PS.: a nice article (from js4MC world) https://github.com/walterhiggins/ScriptCraft/blob/master/docs/YoungPersonsG… -- Jurgis Pralgauskis tel: 8-616 77613; Don't worry, be happy and make things better ;) http://galvosukykla.lt

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turtle coordinates: Y increase downards - as in most graphics API?
by Jurgis Pralgauskis 02 Jul '18

02 Jul '18

Hi, usually in computer graphics Y is counted to increase downwards. I casn do it with: setworldcoordinates(0, 400, 600, 0) but then, "right(..)" turns to the left :/ I could swap: right, left = left, right but on errror I get a bit misleading message >>> right() Traceback (most recent call last): File "<pyshell#10>", line 1, in <module> right() TypeError: left() takes exactly 1 argument (0 given) I thought to make this hack for kids, so better clearer error msgs... Any Ideas? Thanks :) -- Jurgis Pralgauskis tel: 8-616 77613; Don't worry, be happy and make things better ;) http://galvosukykla.lt

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Help needed to run Python for Kids club.
by Jaaba 01 Apr '17

01 Apr '17

Hello, I'm just a newbie in this forum . I was told to contact this group from Eva, from Python Software Foundation (PSF) We have been doing a computer club kind of program for our school students based in Methuen, MA for 3 years. This year we are thinking to introduce Python to our kids from 5th grade and up. I heard about PSF while i was exploring options to run a python club. I'm not sure whats the best way to start a python club with the support of PSF with some grant. If you could throw some light on what we can do as part of our program, that would be greatly appreciated. Thanks Jaffar

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Guest Teach Professional Python
by Peter Farrell 30 Mar '17

30 Mar '17

Hello to the group! I'm an instructor at JobTrain, a non-profit vocational training company that's been in Menlo Park near East Palo Alto for over 50 years. We have construction and medical programs, but I teach Web skills (HTML, CSS, JS). I also prepare them to pass the Salesforce Admin certification exam. I've had 4 students pass it in the last 2 weeks! While introducing programming I always throw in a good amount of Python, but my skills are limited to lots of graphics (Processing) and some Flask. A few cohorts ago (before I started) some Pythonistas came in and taught a week of Python skills: "back end development" was the only description I got. If anybody could come in for a day or two, or a week to teach some Professional Python skills I'd tweet the heck out of it, and the Culinary Arts program would provide lunch for you every day! Would love to hear from anybody interested. Peter Farrell peter(a)farrellpolymath.com

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Children on github
by René Dudfield 29 Mar '17

29 Mar '17

Hello, as part of the move of the pygame (pygame.org) project repository to github we received feedback that github doesn't allow children who have been given consent by their parents to participate. This concerns Germany, and I guess Europe (but I don't know the details). Here is the report on our mailing list from someone involved in an educational organisation in Germany that teaches children python. Apparently they introduce kids to python, and even have some of them contributing to free and open source software projects they are interested in. http://archives.seul.org/pygame/users/Mar-2017/msg00164.html Since I agree with the Python community Code of Conduct that people should not be excluded, this is an issue for us. I was wondering if anyone on the EDU-sig knows about this, or if anyone can give us guidance? This is a delicate issue, and I don't think I have the ability to deal with this. Which is one of the reasons I'm asking for help. If there are no solutions to pass on to this group, I'd like to request some help raising the issue with github to see if they can come up with a solution? thanks,

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to learn one language well, learn at least one other... (meme)
by kirby urner 24 Mar '17

24 Mar '17

On Wed, Mar 22, 2017 at 9:30 PM, kirby urner <kirby.urner(a)gmail.com> wrote: I'm a big believer in "two languages is more than twice as good as knowing > one" because when we compare and contrast, see similarities and > differences, we get that "stereo" view. > > For example, when a Windows user, I'd go over to Linux for awhile and > study hard, then come back to Windows really understanding Windows better > too. > > When you use more than one operating system, you start to get "what's on > OS" (I'd also used mainframes and minis, before hobbyist boxes went viral) > > When you know more bases than 10, you for the first time start to get > "what's a base". > > As I was thinking of examples of how learning two languages helps leverage learning each one, I neglected one of my favorites, yet most obscure: to learn XYZ coordinates (at the heart of high school and to some degree code school), learn non-XYZ methods of doing the same things. For example, we have spherical coordinates (r, alpha, theta) And now, thanks to a tiny group of developers, we have "IVM coordinates" also known as Quadray Coordinates, where the reference vectors spring from the origin (0,0,0,0) like in the methane atom, to the corners of a regular (or not) tetrahedron (1,0,0,0) (0,1,0,0) (0,0,1,0) (0,0,0,1). I bring this up because it's also an area in which I've done a lot of Python programming. Those learning XYZ vectors in the code school sense, as objects, could use these other vectors for comparing and contrasting, even just a little, as spice, as grist. If interested to learn more: https://medium.com/@kirbyurner/thinking-outside-the-box-dcdd9df4ba69 There's also a Wikipedia entry. Kirby

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New articles on Medium.... (not all by me :-D)
by kirby urner 24 Mar '17

24 Mar '17

Useful summary of on-line Python 3 tutorials, starting with the one in docs.python.org itself: https://medium.com/@lockpaddy/10-resources-to-learn-python-3-9a735db7aff9#.… Is it just me or am I sensing a strong pull towards Python 3, away from 2.x? My meditation, also on Medium, published today, is a more generic meditation on code schools. https://medium.com/@kirbyurner/is-code-school-the-new-high-school-30a887417… I mention Python quite a bit, in my appraisal of the looming digital divide and how to bridge it. I've invited more math teachers to comment as what I write concerns them: http://mathforum.org/kb/thread.jspa?threadID=2845880 None of these are new themes on edu-sig. If you check my other Medium writings, you'll find a lot more (also blogs). Kirby

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Young Coders teacher needed at PyCon US
by Catherine Devlin 10 Mar '17

10 Mar '17

Is there a teacher in the house? Python's flagship conference needs an instructor! A description of the event, from last year, on the off chance that you haven't heard of it... https://us.pycon.org/2016/events/letslearnpython/ curriculum at https://github.com/mechanicalgirl/young-coders-tutorial Thank you! -- - Catherine http://catherinedevlin.blogspot.com

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