This presentation contains some tips and good practices about writing clean and maintainable code.

1. Clean Code Tips
September 2013
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2. How do we code?
It is done when (we think) it
is working.
We invest the minimum
amount time to get the best
results.
Are you sure?
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3. Smells
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4. Economic smells
● Over 80% of time spent
reading code instead of
writing it.
● High maintenance cost.
● Unmotivated PEOPLE.
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5. Technical smells
● Classes with 2.000 lines of code
● Methods with over 200 lines of
code
● Lots of comments trying to
explain what the code is
supposed to do
● Duplicated lines of code (Copy &
Paste everywhere)
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6. Why do I have to take care of it?
Because you write it
Every time you write bad
code you are being part of
the problem
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7. Good Practices
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8. Intention-revealing names
Your classes, methods,
functions and attributes
should tell you why they are
there for
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9. Do what you are supposed to do
Each function, method or
class only has to contain the
business logic that they
declare
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10. Do what you are supposed to do
If you are writing an userand-password-checking
method, don’t start a new
session in the system, just
check if the user and
password are correct
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11. Don’t Repeat Yourself principle
Don’t clone code, reuse it
instead
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12. Don’t Repeat Yourself principle
Every time you copy & paste
code, you are exponentially
rising the probability of
having problems in your next
change
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13. Single responsibility principle
There should be only one
possible reason to modify a
class, method or whatever
artifact in your project
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14. Single responsibility principle
They need to have just ONE
RESPONSIBILITY each
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15. Small number of arguments
A small number of arguments
per method or function
indicates that we are...
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16. Small number of arguments
… sharing responsibilities
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17. Small number of arguments
… creating more reusable
data structures
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18. Small number of arguments
… decreasing the amount of
time spent on understanding
the purpose of this piece of
code
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19. Small artifacts
Small packages, classes,
methods, functions are a
signal of good code health
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20. Include comments in complex
algorithms only
This way we reduce the “I
have found comments that
say a different thing that
the code” risk
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21. Include comments in complex
algorithms only
Your code must be readable
and understandable by itself
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22. Tips to achieve this good
practices
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23. From Godzilla...
… to Puppet
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24. Set a maximum number of lines of
code
Limit the amount of allowed
code lines per class, method
and function
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25. Set a maximum number of lines of
code
I.E. A maximum of 10 lines
for methods and functions,
100 for classes
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26. Broken Phone
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27. Avoid comments
Every time you need to write
a comment, read the code
you have written again
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28. Work in pairs
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29. Invite people to read your code
Before commiting a line of
code, ask your partner for
reading it
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30. Invite people to read your code
Does he/she understand
what it is intended to do?
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31. Code is free
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32. Use more classes
If you need to write more
classes in order to reuse your
code, DO IT, THEY ARE
FREE!
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33. Now, do it
Lets start a refactoring
exercise to put in practices
this principles
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34. Now, do it
Is there any volunteer in the
room?
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