This is the public version of an internal presentation I gave at Free Dimension, the company I worked for at the time.

1. Smell your Code!
Yaser Sulaiman
www.free-dimension.com 1

2. These slides are based on an
internal presentation I gave
@ Free Dimension (FD)
www.free-dimension.com 2

3. It contained examples from real
projects
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4. FD agreed to publish it online under
a CC BY-NC-SA license…
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5. after removing, or disguising, the
real examples
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6. Disguised examples are marked
with
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7. Our road map
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8. What? Why? How?
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9. If you can take away only 1 lesson…
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10. Don’t Repeat Yourself!
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11. This rule is so important I have to
break it
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12. Don’t Repeat Yourself!
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13. What? Why? How?
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14. Code smells?!
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15. Warning signs
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16. photo by pj_in_oz
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17. Surface indications of deeper
problems
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18. photo by BenChenowethWork
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19. Surface indications of deeper
problems
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20. www.free-dimension.com 20

21. What? Why? How?
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22. The bigger picture
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23. Software
Quality
Code Quality
Code Smells
not to scale
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24. Writing HQ code should be the
priority
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25. www.free-dimension.com 25

26. www.free-dimension.com 26

27. One path to cleaner code goes
through code smells
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28. What? Why? How?
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29. Can you smell code?!
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30. photo by lanceball
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31. There’re many code smells
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32. The following smells are just a
subset
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33. They’re some of the smells I smelled
while working here
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34. Code Smell #1
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35. DupIicated code DupIicated code
DupIicated code DupIicated code
DupIicated code DupIicated code
DupIicated code DupIicated code
DupIicated code DupIicated code
DupIicated code DupIicated code
DupIicated code DupIicated code
DupIicated code DupIicated code
DupIicated code DupIicated code
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36. The nastiest code smell
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37. DupIicated code DupIicated code
DupIicated code DupIicated code
DupIicated code DupIicated code
DupIicated code DupIicated code
DupIicated code DupIicated code
DupIicated code DupIicated code
DupIicated code DupIicated code
DupIicated code DupIicated code
DupIicated code DupIicated code
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38. Example #1
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39. BooksController
&
NotebooksController
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40. The diff test
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41. FD Employees Only!
ignoring whitespace differences
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42. Example #2
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43. MessagesController
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44. class MessagesController extends AppController {
function zebra_inbox() {
// inbox code
}
function zebra_view($id = null) {
// view message code
}
}
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45. class MessagesController extends AppController {
function zebra_inbox() {
// inbox code
}
function elephant_inbox() {
// inbox code
}
function zebra_view($id = null) {
// view message code
}
function elephant_view($id = null) {
// view message code
}
}
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46. But then came the penguin, the
dolphin, the chimp,…
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47. Refactor!
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48. class MessagesController extends AppController {
function zebra_inbox() {
$this->setAction('inbox');
}
function elephant_inbox() {
$this->setAction('inbox');
}
function inbox() {
// inbox code
}
function zebra_view($id = null) {
$this->setAction('view', $id);
}
function elephant_view($id = null) {
$this->setAction('view', $id);
}
function view($id = null) {
// view message code
}
}
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49. Added plus: no duplicated views
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50. FD Employees Only!
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51. Code Smell #2
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52. Too many parameters
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53. How many is too many?
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54. www.free-dimension.com 54

55. www.free-dimension.com 55

56. Example
(brace your noses!)
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57. public abstract class AProvider
{
public abstract void AddToFamily(int familyId, string firstName, string sex,
string photo, DateTime? birthDate, string birthCountry, string birthCity,
bool living, DateTime? deathDate, string country, string city, string email,
string homepage, string mobilePhone, string biography, string jobTitle,
string maritalStatus, string spouse, int order, int? fatherId);
public abstract void UpdateInFamily(int id, int familyId, string firstName,
string sex, string photo, DateTime? birthDate, string birthCountry,
string birthCity, bool living, DateTime? deathDate, string country,
string city, string email, string homepage, string mobilePhone,
string biography, string jobTitle, string maritalStatus, string spouse,
int order, int? fatherId);
}
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58. !
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59. I misunderstood coupling. My bad!
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60. public abstract class AProvider
{
public abstract void AddToFamily(Person person);
public abstract void UpdateInFamily(Person person);
}
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61. The remaining smells have many
examples; check the repository
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62. Code Smell #3
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63. Not following a coding
convention/standard/style
consistently
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64. Not following a coding
convention/standard/style
consistently
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65. The specifics doesn’t really matter;
what matters most is consistency
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66. Code Smell #4
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67. // code.CommentOut();
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68. “Commented-out code is an
abomination.”—Uncle Bob
photo used with permission of Uncle Bob
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69. Don’t commit commented-out code
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70. Code Smell #5
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71. redundant
// This is a comment
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72. Comments
should focus on
What? Why? How?
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73. What? Why? How?
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74. I may have come off as an a$$
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75. My code smells as bad as everyone
else’s.. sometimes even worse
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76. But I’m aware of my smells
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77. I try my best to prevent them
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78. I don’t ignore them; I deal with
them
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79. I smell my code
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80. You should smell your code too
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81. If you want to sniff more…
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82. more than just code smells
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83. …</presentation>
<questions>…
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