Trouble with turtles

11 Feb, 2018

Theodore M writes:

Hello. Working in python with my daughter, but stuck on this error:

Python 3.6.4 (v3.6.4:d48ecebad5, Dec 18 2017, 21:07:28) [GCC 4.2.1 (Apple Inc. build 5666) (dot 3)] on darwin Type "copyright", "credits" or "license()" for more information. >>> import turtle Traceback (most recent call last): File "", line 1, in import turtle File "/Users/mac/Documents/turtle.py", line 2, in t=turtle.Pen() AttributeError: module 'turtle' has no attribute 'Pen'

It looks as if you might have created a file called turtle.py in your Documents directory (/Users/mac/Documents), and because you're running IDLE from the same directory (I assume), that file is being loaded before the actual turtle module. If you delete this file and try again, hopefully you'll have more success.


Becoming an expert?

12 Jan, 2018

Femi A writes:

I just got your book: Python for kids and I’m excited to start reading it. I am 36 years old and I would like to learn computer programming. I figure python would be a good place to start. Is it possible to become an expert at python in 6 months with intensive efforts? And if it is can you please let me know how to go about that, the steps to take etc...

I would say this isn't necessarily a Python, nor even a general computer programming question. It's more a question about how you define expertise, what that means from a learning perspective, and what your goals really are. If you define expertise in terms of Malcolm Gladwell's 10,000 hour rule and spend 4-5 hours a day at it, you'll be an "expert" in 6 years or so [1]. So if your goal is to call yourself an "expert", then that's probably your timeline.

If your goal is to develop some software, make a meaningful contribution to an open source project, or something along those lines, and are well motivated, it's certainly possible to do that, and more, with 6 months of dedicated effort. So, how to get to the point where you're at least confident in your coding? Start with a beginners book, funnel that knowledge in developing a few simple projects to build your experience; then perhaps look for a more advanced Python book (O'Reilly's Python Cookbook might be a good option), followed by some more advanced projects, again for the experience. Just remember, it's more important to be coding than reading about it.

Hope that helps.

[1]: Also see this Business Insider article for a counterpoint to the 10K hour principle.


Apple's Broken Parental Controls

12 Nov, 2017

What's a nice way to give a kid a limited amount of spending freedom, and letting them buy some things without being able to decimate your credit card? iTunes Voucher -- seems reasonable right?

So... redeeming voucher... Enter Apple ID password. Okay. Use camera to enter code. That's helpful. Please enter your credit card security code. Wait, what? Sigh. Fine.

Hand iPad back to kid. "Right, you can buy something now."

"How about this one?"

"Nooo that's too expensive. Find another one."

"What about this?"

"Yes okay, that works. You can click this Buy button here."

"Pa??" iPad thrust back into your hands.

Enter Apple ID password

Sigh. Okay. Why the heck did I bother to add a nice long, secure password for his account?

Ask for your parent's approval. Click Ask... time passes... Nothing happened. Huh? Click Buy again.

Enter Apple ID password.

WTH? Just did that! For. The. Same. Game.

Ask for your parent's approval (they can also authorise on this device). Yes, but that defeats the purpose. The whole point was to let the kid buy a few things himself. Click Ask.

A message arrives on my phone: Your iDevice-obsessed post-toddler wants to purchase lego-something-or-other-game. Are you sure he's not already spending too much time on devices already? Woohoo, finally got the request! Unlock phone. Wait, WTH! Where's the authorisation dialog gone? Settings > Parental controls? Nope nothing there. Search > Parental Controls. Nothing there either. Sigh. Back to the kid's device again. Click Buy... again.

Enter Apple ID password

Whatever. Stupid long passwords.

Ask for your parent's approval. Stab Ask. Kid now looking at you strangely because you're starting to mutter rude words under your breath.

A message arrives on my phone: Your iDevice-obsessed post-toddler wants to purchase lego-something-or-other-game. Yes I know. It's me not the kid -- how's a child supposed to figure this out? Touch the dialog correctly this time.

A message arrives on the kid's iPad: The bossy parental unit has authorised your purchase. Excellent. Hand back device to kid.

"Pa??" iPad thrust back into my hands.

What's the problem now? Oh, the buy button has turned into a get link. Only it doesn't look like a link at all. It's just the text GET. WTH? Where are the UI standards? Isn't this supposed to be a button??

Your purchase is downloading. Finally. Mutter mutter Apple mutter.

...5 mins passes...

"Pa?? I'm bored with this game. Can I try this one?"

"Fine, okay". Click Buy.

Enter Apple ID password

.

.

.

Angry, from Disney's Inside Out


How Many Hours

11 Nov, 2017

Xing Y writes:

This is Xing Yanchao from the city of Qingdao, Shandong province, China, a big beautiful coastal city with 7 million citizens. I'm very interested in teaching kids to program, and plan to choose your book as the teaching material (In Chinese, ^_^). The kids may be between 8~12, how many hours do you suggest for us to finish the whole book?

Thank you in advance!

I think at least an hour a chapter for Part 1 of the book, but the chapters on functions, modules, classes and objects will probably take a bit longer. 12-15 hours is probably reasonable to cover most of Part 1 in a classroom setting, especially considering there should be a bit of time for kids to play around and try things for themselves, rather than following it exactly. Learn through play is important, particularly with a subject that can be pretty dry. Parts 2 and 3 are more difficult to estimate. I would actually suggest to just use Part 1 in the class, then let the kids come up with projects for themselves, and use the last two parts of the book as a reference (for example, let them create something for themselves, but use chapters 13-18 to figure out some of what they decide to do). Just a thought.


Multiplying Strings

10 Oct, 2017

Robin L writes (excerpted):

I am trying to teach myself how to code and thought this was a good place to begin. I am having trouble with the "multiplying strings" section. I don't know anyone else who codes so I am hoping that you are still available at this email. This is the part about printing a letter in the shell. For some reason when I run mine the "print()" keeps actually printing "()".

Can you please help me figure out what I am doing wrong?

There's a pretty major difference between printing with older versions of Python (Python2.7 and earlier) and newer versions (Python3 and later). In Python2, print is a statement, which means this works fine:

print "hi there"

If you try that in Python3, you'll get an error:

print "hi there"
  File "<stdin>", line 1
    print "hi there"
               ^
SyntaxError: Missing parentheses in call to 'print'

That's because print in Python3 is a function not a statement.

Why does that make a difference? In Python2, this code...

print()

...is a print statement followed by an empty tuple. You're effectively telling Python to "print this empty tuple", and by quirk of the way the print statement works, you get (). The exact same code in Python3 is a function name (print) followed by an open bracket, no parameters, and a closing bracket. You're providing no parameters and the function prints nothing as a consequence. And that, basically, is the difference.

Cutting a long story short - all you're doing wrong is running an older version of Python. Check chapter one, and follow the instructions to install Python3, and the code will work as you expect.