The document outlines various coding practices aimed at improving code quality through refactoring and addressing code smells. It discusses methods such as extracting methods and classes, handling divergent changes, and emphasizes the importance of not over-refactoring when code is functioning well. References for further reading on refactoring and clean code are also provided.

1. Code Smells & Refactoring
by Carlos Mourullo

2. Who I am?
carlosmourullo@gmail.com
@kmur48
Spanish guy who is trying to grow personally and professionally, little by little,
every day.
When the people ask me what I do I usually say “I solve problems”.
I’m also a music lover, tennis player and bike rider.

3. Where I’m working?
We are hiring!!! We are hiring!!!

4. Boy Scout rule
“Always leave the playground cleaner than
you found it” [Uncle Bob]
But!!
 What is the playground?
 What does clean mean?
For me
 Is the lines that you need to
modify to include a new
functionality
 Easy to understand and
modify

5. Comments
We use these when the code is not very good / easy to
understand… Whenever you feel the need to comment on
something, write a method!
public function printOwing($amount) {
$this->printBanner();
//print details
echo "name: $this->name n";
echo "amount: $amount n";
}
public function printOwing($amount) {
$this->printBanner();
$this->printDetails($amount);
}
public function printDetails($amount) {
echo "name: $this->name n";
echo "amount: $amount n";
}
How?
 Extract Method (use good naming, please)

6. Duplicate code
Find a way to extract this piece of code: duplicate,
unrelated class or similar
How?
 Duplicate: use Extract Method and invoke the code from both places
 Two unrelated classes: consider using Extract Class
 Similar: you can use Form Template Method

8. Long method
Longer = more difficult to understand [switch context]
How?
 Use Extract Method to extract conditionals and loops also
 If you end up with a lot of parameters, use Replace Temp with Query
$basePrice = $this->_quantity * $this->_item Price;
if ($basePrice > 1000)
return $basePrice * 0.95;
else
return $basePrice * 0.98;
…
if ($this->basePrice() > 1000)
return $this->basePrice() * 0.95;
else
return $this->basePrice() * 0.98;
…
private function basePrice() {
return $this->_quantity * $this->_item Price;
}

9. Data clumps
Group of three or four data items together in many
places
How?
 Use Extract Class to turn clumps into an object. One immediate benefit is
that you can simplify method calling

10. Data class
Class that only has getting and setting. Give it some
responsibility!
How?
 Look for where getting/settings are used by other classes, them try to use
Move Method or Extract Method

11. Speculative generality
Solve today’s problems, not the future ones!
Sometimes we create some new cases to handle
things that aren’t required
How?
Delete!!
 Remove Parameters
 Collapse Hierarchy

12. Divergent changes
One class that is commonly changed in different
ways for different reasons
E.g. change your DB or use a new payment system
How?
 Separate these divergent responsibilities. Sometimes two objects are better
than one, use Extract Class

13. Shotgun Surgery
Every time you make any kind of change you have to
make a lot of little changes to a lot of different
classes… easy to miss something
How?
 Move Method
 Move Field to put all changes into a single class

14. Boy Scout rule
Deciding when to start refactoring, and when to stop is just as important to the
refactoring process as knowing how to operate the mechanics of a refactoring

15. If it ain’t broke, don’t fix it!
Don’t go too far
RESPECT the work of others
Thanks!!

16. Bibliography
 http://martinfowler.com/books/refactoring.html
 https://www.amazon.co.uk/Clean-Code-Handbook-Software-
Craftsmanship/dp/0132350882
 https://medium.com/@elmendalerenda/if-it-s-not-broke-don-t-fix-it-
3a11d4170ec4#.k2eew8whi
 https://blog.codinghorror.com/code-smells/
 http://www.industriallogic.com/wp-
content/uploads/2005/09/smellstorefactorings.pdf
 https://sourcemaking.com/refactoring/smells

17.  p3Hotels - http://www.p3hotels.com/
 https://jobbio.com/ie/p3hotels-careers
 GTS - http://www.goodtravelsoftware.com/
 http://www.goodtravelsoftware.com/jobs.php
Hiring!!