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Clean code: extract until it reads
Principles · Python
Clean code: extract until it reads
Turn a long function into named steps you can read from top to bottom.
12 steps
5 chapters
~4 min at 1.25×
#extract method
#long method
#readability
#split variable
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Every step
Problem
Steps 1–3
01
A checkout that works
Before
02
A discount in the wrong place
Code smell
03
Undo, then extract
Plan
Refactor
Steps 4–7
04
Pull out the guard
Extract Function
05
Pull out the subtotal
Extract Function
06
One name per meaning
Split Variable
07
Pull out delivery
Extract Function
Payoff
Step 8
08
The discount, in the right place
Payoff
Python bonus
Steps 9–10
09
A loop that only adds
Generator expression
10
Sum a generator
Generator expression
Recap
Steps 11–12
11
Where we started, where we ended
Before / after
12
When to reach for it
Takeaways