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Stop Using Magic Numbers and Variables in Your Code
No one will understand your program. Not even you
Have you ever scratched your head reading code you didn’t write yourself?
Of course you have.
You’re not a bad programmer who can’t read code. Maybe the programmer who wrote the code was a magician — the wrong kind of magician.
Keep this quote in the back of your head while coding.
“Always code as if the guy who ends up maintaining your code will be a violent psychopath who knows where you live.” — John Wood
Many programs suffer from the fact that they aren’t written with another reader in mind. If you don’t have the violent psychopath in the back of your head while writing code, chances are some bad code will sneak in.
You might have a hard time reading your own code as well after a while unless you write code that everyone will understand forever.
What Is Magic?
Please don’t confuse the magic we are talking about today with magic methods (Dunder methods).
You have most likely used __init__ as an initializer for your class. Have you tried using __str__ to control what happens when you print your object?
The magic we don’t like is magic variables and magic numbers.
Magic variables
A magic variable has a variable name that does not reflect what it represents. The name is complete gibberish, and it isn’t meaningful to the reader.
The following code declares a magic variable:
a = [i for i in range(1,7)]a can be anything. Sure, it’s a list ranging from 1–6, but how will we use it? Grades, doors in the room, leftovers in the fridge?
There is no way you can know what this code is supposed to do.
dice_alternatives = [die for die in range(1,7)]The code was all about dice, and the code created a list based on the number of faces the die had. Now it makes sense.
