The document discusses 'code smells,' which are indicators of potential problems in source code, such as speculative generality, duplicated code, and long methods. It provides examples of bad code practices and illustrates how to refactor them for clarity and maintainability. Additionally, it mentions tools for detecting code smells and emphasizes the importance of writing clean, comprehensible code.

1. Smelling Your Code
Raju Mazumder
Sr. Software Engineer
Tasawr Interactive
Rubyist, Java and PHP Developer
like to work fun and challenging environment
Web: www.rajumazumder.com
Twitter: @rajuniit

2. What is Code Smell?

3. Wikipedia Definition
“ code smell is any symptom in the source code of a program
that possibly indicates a deeper problem. ”

4. Speculative Generality
Large Class Long Method
Dead Code Comment
Switch Case Primitive Obsession
Duplicated Code
Long Parameter List
Meaningful Names
Divergent Change Shotgun Surgery

5. Dead Code
Harder to comprehend the code base.
Wasted time - reading through, or even changing dead code.
Meaningful Names
public $d; // what does it mean? Days or diameter
public $days; // clean
public function getinvcdtlmt() {
//do something
}
public function getInvoiceableCreditLimit() {
//do something
}

6. Comment is smell
Which one is clearer?
//check is employee active
if ( $employee->isActive() ) {
//do something;
}
if ( $employee->isActive() ) {
//do something;
}

7. Duplicate Code
Code repeated in multiple places.

8. Bad Example
<?php
function displayPHPExperSpeakerInfo($speakerId)
{
$speaker = new Speaker();
$speaker = $speaker->find($speakerId);
if($speaker->isSixMinuteSpeaker()) {
$name = $speaker->getName();
$designation = $speaker->getDesignation();
echo "Name: ". $name;
echo "Designation:". $designation;
} else {
$name = $speaker->getName();
$designation = $speaker->getDesignation();
$topic = $speaker->getTopicName();
echo "Name:". $name;
echo "Designation: " . $designation;
echo "Topic: ". $topic;
}
}
displayPHPExperSpeakerInfo(2);

9. Refactor continue...
<?php
function displayPHPExperSpeakerInfo($speakerId)
{
$speaker = new Speaker();
$speaker = $speaker->find($speakerId);
displayGeneralInformation($speaker);
if ($speaker->isTwelveMinuteSpeaker()) {
$topic = $speaker->getTopicName();
echo "Topic: " . $topic;
}
}
function displayGeneralInformation($speaker)
{
$name = $speaker->getName();
$designation = $speaker->getDesignation();
echo "Name: " . $name;
echo "Designation:" . $designation;
}
displayPHPExperSpeakerInfo(2);
Note: We can imrove it more. Its just an example

10. Long Method
Longer Methods are difficult to understand
Too many conditions and loops
Long Class
Single responsibility Principle Violated

11. Bad Example
function gotoPhpExpertsSeminar2011() {
//wake up morning
//taking my breakfast
//take vehicle
//check confirmation code
//take a seat
}

12. Refactor Continue...
function gotoPhpExpertsSeminar2011() {
wakeUpMorning();
takeBreakFast();
takeVehicle();
checkConfirmationCode();
takeSeat();
}
Note: We can imrove it more. Its just an example

13. Long Parameter List
Lots of parameters will make code harder to
understand.

14. Bad Example..
function getSpeakers($type = '', $experience = 0,
$zce = null, $newSpeaker = null)
{
$criteria = array();
if ($type) {
$criteria[] = "type = '{$type}' ";
}
.......
........
if ($criteria) {
$condition = implode('AND ', $criteria);
} else {
$condition = '1=1';
}
$speakers = $db->fetchQuery("select * from speakers
WHERE {$condition}");
return $speakers;
}
$sixMinuteSpeakers = getSpeakers('six_minute');
$zecSpeakers = getSpeakers('',0,true);
$tweleveMinuteSpeakers = getSpeakers('twelve_minute');

15. Refactor continue..
function getSpeakersByType($type = 'six_minute')
{
$speakers = $db->fetchQuery("select * from speakers
WHERE type = '{$type}'");
return $speakers;
}
function getZceSpeakers()
{
$speakers = $db->fetchQuery("select * from speakers
WHERE zce = 1");
return $speakers;
}
$sixMinuteSpeakers = getSpeakersByType();
$zecSpeakers = getZceSpeakers();
$tweleveMinuteSpeakers = getSpeakersByType('twelve_minute');
Note: We can imrove it more. Its just an example

16. Refactor continue..
function getSpeakersByOptions(array $options)
{
$condition = prepareWhere($options);
$speakers = $db->fetchQuery("select * from speakers
WHERE {$condition}");
return $speakers;
}
function prepareWhere($options)
{
$criteria = array();
foreach ($options as $option => $value) {
switch ($option) {
case 'type': $criteria[] = "type = '{$value}' "; break;
case 'zce': $criteria[] = "zce = '{$value}' "; break;
case 'experience': $criteria[] = "experience = '{$value}' "; break;
default: break;
}
}
if ($criteria) {
$condition = implode('AND ', $criteria);
} else {
$condition = '1=1';
}
return $condition;
} Note: We can imrove it more. Its just an example

17. Refactor Continue...
$options = array('type' => 'six_minute');
$sixFameSpeakers = getSpeakersByOptions($options);
$options = array('zce' => 1);
$zecSpeakers = getSpeakersByOptions($options);
$options = array('type' => 'twelve_minute');
$tweleveMinuteSpeakers = getSpeakersByOptions($options);
Note: We can imrove it more. Its just an example

18. Smell Detection Tools
Phpcpd
https://github.com/sebastianbergmann/phpcpd
PHP Code Sniffer
http://pear.php.net/package/PHP_CodeSniffer/redirected
Phpdepend
http://pdepend.org/download/index.html
phploc
https://github.com/sebastianbergmann/phploc
phpmd
http://phpmd.org/

19. Resources
Clean Code
– Robert C. Martin
Refactoring: Improved the design of existing code
– Martin Fowler

20. Thanks
“Code is the mirror of the developer”
“So let's Write Beautiful Code”
Questions?