ptg20573278
PREFACE xix
While you do these exercises, typing each one in, you will make mistakes. It’s inevitable; even seasoned
programmers would make a few. Your job is to compare what you have written to what’s required and fix
all the dierences. By doing so, you will train yourself to notice mistakes, bugs, and other problems.
Ask, Don’t Stare
If you write code, you will write bugs. A “bug” means a defect, error, or problem with the code you’ve
written. The legends say that this comes from an actual moth that flew into one of the first computers
causing it to malfunction. Fixing it required “de-bugging” the computer. In the world of software, there are
a lot of bugs. So many.
Like that first moth, your bugs will be hidden somewhere in the code, and you have to go find them. You
can’t just sit at your computer screen staring at the words you’ve written hoping that the answer jumps
out at you. There is no more additional information you can get doing that, and you need additional
information. You need to get up and go find the moth.
To do that you have to interrogate your code and ask it what is going on or look at the problem from a
dierent view. In this book I frequently tell you to “stop staring and ask.” I show you how to make your
code tell you everything it can about what’s going on and how to turn this into possible solutions. I also
show you how to see your code in dierent ways, so you can get more information and insight.
Do Not Copy-Paste
You must type each of these exercises in, manually. If you copy-paste, you might as well not even do
them. The point of these exercises is to train your hands, your brain, and your mind in how to read, write,
and see code. If you copy-paste, you are cheating yourself out of the eectiveness of the lessons.
Using the Included Videos
Learn Python 3 the Hard Way has an extensive set of videos demonstrating how the code works and,
most importantly, how to break it. The videos are the perfect place to demonstrate many common errors
by breaking the Python code on purpose and showing you how to fix it. I also walk through the code using
debugging and interrogation tricks and techniques. The videos are where I show you how to “stop staring
and ask” the code what’s wrong. You can watch these videos online at informit.com/title/9780134692883.
A Note on Practice and Persistence
While you are studying programming, I’m studying how to play guitar. I practice it every day for at least two
hours a day. I play scales, chords, and arpeggios for an hour and then learn music theory, ear training,
songs, and anything else I can. Some days I study guitar and music for eight hours because I feel like it
and it’s fun. To me repetitive practice is natural and just how to learn something. I know that to get good
at anything I have to practice every day, even if I suck that day (which is often) or it’s dicult. Keep trying,
and eventually it’ll be easier and fun.
我花一小时演奏音阶，和弦和琶
音，然后学习音乐理论，听力训
练，歌曲和其他任何我能做的事
情。
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