1. Professional Refactoring
International PHP Conference 2009
Spring Edition
Mayflower GmbH 2009 1

2. • Senior Developer / Team Lead at
Mayflower GmbH
• Reporting and Rating Apps
• QA and PHP 5 Migration
consultings
• PHP since 1999 (3.0.16)
• phpMyFAQ since 2001
Mayflower GmbH 2009 2

3. Who are you?
• What are you doing?
• What‘s your team size?
• Using MVC?
• Who‘s using Continous Integration?
• PHPUnit?
• 80% code coverage?
Mayflower GmbH 2009 3

4. Your projects...
• What‘s your average project lifetime?
• Is there PHP code more than 5 years old?
• How many lines of code?
• How many change requests per year?
• Has there been a specification?
• Were all features in the first
release as specified?
Mayflower GmbH 2009 4

5. What is Refactoring?
„Refactoring is a disciplined technique for
restructuring an existing body of code, altering
its internal structure without changing its
external behavior.“
-Martin Fowler, www.refactoring.com
Mayflower GmbH 2009 5

6. Why especially PHP?
(c) www.medrehab.com
Code Aging!
Mayflower GmbH 2009 6

7. A PHP Project in 2000 ...
• no coding standards, no PHPDoc
• no MVC, no Design Patterns
• if you were lucky, someone used a
template system
• nobody cared about XSS or CSRF
a lot of changes in business logics
• never got refactored,
documentated or even tested ...
Mayflower GmbH 2009 7

8. ... because it worked!
Mayflower GmbH 2009 8

9. In the year 2009
• change requests get more and
more expensive
• the bug rate is always
increasing
• the development team
motivation is decreasing
• requirement changes are
almost impossible
• new team members need a lot
of time to be productive
Mayflower GmbH 2009 9

10. Management point of view
Costs per Change Request
rising frequency
Dead end!
Benefit per Change Request
Mayflower GmbH 2009 10

11. Start refactoring now!
Mayflower GmbH 2009 11

12. But hey, stop!
Mayflower GmbH 2009 12

13. Don‘t refactor ...
• weeks before a
important release
• only with a lot of junior
developers
• parallel with
development tasks
Mayflower GmbH 2009 13

14. Before starting refactoring
• define a coding standard
• avoids spaghetti code
• speeds up maintainability
• improves productivity
• fix your API specs
• complete your documentation
Mayflower GmbH 2009 14

15. During the refactoring...
• stay calm
• take a lot of good developers and
a bunch of juniors
• write tests, tests, tests
• don‘t let developer refactor their
own code
• don‘t let junior developers
refactor alone
Mayflower GmbH 2009 15

16. About Unittests
• Testing is essential during refactoring
• Problems
• most of old code isn‘t
„unittestable“
• API breaks during refacotoring
• Solution
• Selenium tests instead
• iterative refactoring
Mayflower GmbH 2009 16

17. (c) BMW AG
Okay, let‘s start!
Mayflower GmbH 2009 17

18. Back to Martin Fowler
„Refactoring is a disciplined technique for
restructuring an existing body of code, altering
its internal structure without changing its
external behavior.“
-Martin Fowler, www.refactoring.com
Mayflower GmbH 2009 18

19. Forms of refactoring
•Renaming
•Extraction
•Changing signature
•Pull up / Pull down
Mayflower GmbH 2009 19

20. Renaming
/**
* Remove a word from the stop word dictionary
*
* @param integer $id
*
* @return void
*/
public function remove($id)
{
$sql = sprintf(quot;DELETE FROM $this->tablename WHERE id = %d AND lang =
'%s'quot;, $id, $this->language);
$this->db->query($sql);
}
Mayflower GmbH 2009 20

21. Renaming
/**
* Remove a word from the stop word dictionary
*
* @param integer $stopword_id ID of the stop word
*
* @return void
*/
public function remove($stopword_id)
{
$delete = sprintf(quot;DELETE FROM $this->tablename WHERE id = %d AND lang =
'%s'quot;, $stopword_id, $this->language);
$this->db->query($delete);
}
Mayflower GmbH 2009 21

22. Restructuring
/**
* Remove a word from the stop word dictionary
*
* @param integer $stopword_id ID of the stop word
*
* @return void
*/
public function remove($stopword_id)
{
$delete = sprintf(quot;DELETE FROM $this->tablename WHERE id = %d AND lang =
'%s'quot;, $stopword_id, $this->language);
$this->db->query($delete);
}
Mayflower GmbH 2009 22

23. Restructuring
/**
* Remove a word from the stop word dictionary
*
* @param integer $stopword_id ID of the stop word
*
* @return void
*/
public function remove($stopword_id)
{
$delete = sprintf(quot;DELETE FROM %s WHERE id = %d AND lang = '%s'quot;,
$this->tablename,
$stopword_id,
$this->language);
$this->db->query($delete);
}
Mayflower GmbH 2009 23

24. Extraction
/**
* Remove a word from the stop word dictionary
*
* @param integer $stopword_id ID of the stop word
*
* @return void
*/
public function remove($stopword_id)
{
$delete = sprintf(quot;DELETE FROM %s WHERE id = %d AND lang = '%s'quot;,
$this->tablename,
$stopword_id,
$this->language);
$this->db->query($delete);
}
Mayflower GmbH 2009 24

25. Extraction
public function remove($stopword_id)
{
$delete = sprintf(quot;DELETE FROM %s WHERE id = %d AND lang = '%s'quot;,
$this->tablename,
$stopword_id,
$this->language);
$this->_execute($delete);
}
private function _execute($query)
{
return $this->db->query($query)
}
Mayflower GmbH 2009 25

26. Changing signature
/**
* Remove a word from the stop word dictionary
*
* @param integer $id ID of the stop word
*
* @return void
*/
public function remove($stopword_id)
{
$delete = sprintf(quot;DELETE FROM %s WHERE id = %d AND lang = '%s'quot;,
$this->tablename,
$stopword_id,
$this->language);
$this->db->query($delete);
}
Mayflower GmbH 2009 26

27. Changing signature
/**
* Remove a word from the stop word dictionary
*
* @param integer $stopword_id ID of the stop word
* @param boolean $logging Log removal? Default: false
*
* @return void
*/
public function remove($stopword_id, $logging = false)
{
$delete = sprintf(quot;DELETE FROM %s WHERE id = %d AND lang = '%s'quot;,
$this->tablename,
$stopword_id,
$this->language);
if ($logging) {
$this->_logAction('removal', $stopword_id);
}
$this->db->query($delete);
}
Mayflower GmbH 2009 27

28. Pull up / Pull down
x
Mayflower GmbH 2009 28

29. Pull up / Pull down
x
Mayflower GmbH 2009 29

30. Pull up / Pull down
x
x x
Mayflower GmbH 2009 30

31. Tips & Tricks
• Always add PHPDoc if it‘s missing
• Never trust automatic refactoring of IDEs
• Don‘t do refactoring for fun
• Write as much unittests as possible
Mayflower GmbH 2009 31

32. Any questions? Mayflower GmbH 2009 32

33. Thank you very much for your attention!
Thorsten Rinne
Mayflower GmbH
Mannhardtstraße 6
D-80538 München
+49 (0) 89 24 20 54 - 31
thorsten.rinne@mayflower.de
Mayflower GmbH 2009 33