Presentation from phpday 2011 about software metrics and tools in php Abstract: Esiste un modo per decidere se una porzione di codice è migliore di un altra? Le metriche del codice forniscono misure oggettive sulla qualità del codice stesso. Nel talk verranno introdotte le principali metriche, gli strumenti che permettono di ricavarle e il loro utilizzo nel flusso di sviluppo.

1. #phpday
Dica trentatrè <?php echo ’33’ ?>
Controllare lo stato di salute di una applicazione con le
metriche del codice
Michele Orselli (@_orso_)

2. #phpday
Code Metrics

3. Measure of some property of a piece
#phpday
of software (Wikipedia)

4. #phpday
Who Cares?

5. #phpday
How long will it take to add feature X?

6. #phpday
Internal vs External Quality

7. Code Metrics as a mean to expose
#phpday
internal quality

8. #phpday
How long will it take to add feature X?

9. #phpday
Classic

10. Lines and Numbers
Lines
LOC: Lines Of Code
#phpday ELOC: Executable LOC
CLOC: Comment LOC
NCLOC: Non-Comment LOC
Numbers
NOC: Number Of Classes
NOM: Number Of Methods
NOP: Number Of Packages

11. Lines and Numbers
1 <?php
2
Lines 3 namespace shapestwodimensional;
4
5 abstract class shape {
6 /* Returns the area of the shape */
#phpday 7 abstract function area();
8 }
9
10 class circle extends shape {
11 public function area() {}
12
13 /* Ret the diameter of the circle */
Numbers 14 public function diameter() {}
15 }
16
17 class triangle extends shape {
18
19 public function area() {}
20 }
21
22 ?>

12. Lines and Numbers
1 <?php
2
Lines 3 namespace shapestwodimensional;
4
LOC 22 5 abstract class shape {
6 /* Returns the area of the shape */
#phpday 7 abstract function area();
8 }
9
10 class circle extends shape {
11 public function area() {}
12
13 /* Ret the diameter of the circle */
Numbers 14 public function diameter() {}
15 }
16
17 class triangle extends shape {
18
19 public function area() {}
20 }
21
22 ?>

13. Lines and Numbers
1 <?php
2
Lines 3 namespace shapestwodimensional;
4
LOC 22 5 abstract class shape {
6 /* Returns the area of the shape */
#phpday CLOC 2 7 abstract function area();
8 }
9
10 class circle extends shape {
11 public function area() {}
12
13 /* Ret the diameter of the circle */
Numbers 14 public function diameter() {}
15 }
16
17 class triangle extends shape {
18
19 public function area() {}
20 }
21
22 ?>

14. Lines and Numbers
1 <?php
2
Lines 3 namespace shapestwodimensional;
4
LOC 22 5 abstract class shape {
6 /* Returns the area of the shape */
#phpday CLOC 2 7 abstract function area();
8 }
NCLOC 20 9
10 class circle extends shape {
11 public function area() {}
12
13 /* Ret the diameter of the circle */
Numbers 14 public function diameter() {}
15 }
16
17 class triangle extends shape {
18
19 public function area() {}
20 }
21
22 ?>

15. Lines and Numbers
1 <?php
2
Lines 3 namespace shapestwodimensional;
4
LOC 22 5 abstract class shape {
6 /* Returns the area of the shape */
#phpday CLOC 2 7 abstract function area();
8 }
NCLOC 20 9
10 class circle extends shape {
ELOC 3 11 public function area() {}
12
13 /* Ret the diameter of the circle */
Numbers 14 public function diameter() {}
15 }
16
17 class triangle extends shape {
18
19 public function area() {}
20 }
21
22 ?>

16. Lines and Numbers
1 <?php
2
Lines 3 namespace shapestwodimensional;
4
LOC 22 5 abstract class shape {
6 /* Returns the area of the shape */
#phpday CLOC 2 7 abstract function area();
8 }
NCLOC 20 9
10 class circle extends shape {
ELOC 3 11 public function area() {}
12
13 /* Ret the diameter of the circle */
Numbers 14 public function diameter() {}
15 }
NOP 1 16
17 class triangle extends shape {
18
19 public function area() {}
20 }
21
22 ?>

17. Lines and Numbers
1 <?php
2
Lines 3 namespace shapestwodimensional;
4
LOC 22 5 abstract class shape {
6 /* Returns the area of the shape */
#phpday CLOC 2 7 abstract function area();
8 }
NCLOC 20 9
10 class circle extends shape {
ELOC 3 11 public function area() {}
12
13 /* Ret the diameter of the circle */
Numbers 14 public function diameter() {}
15 }
NOP 1 16
17 class triangle extends shape {
NOC 3 18
19 public function area() {}
20 }
21
22 ?>

18. Lines and Numbers
1 <?php
2
Lines 3 namespace shapestwodimensional;
4
LOC 22 5 abstract class shape {
6 /* Returns the area of the shape */
#phpday CLOC 2 7 abstract function area();
8 }
NCLOC 20 9
10 class circle extends shape {
ELOC 3 11 public function area() {}
12
13 /* Ret the diameter of the circle */
Numbers 14 public function diameter() {}
15 }
NOP 1 16
17 class triangle extends shape {
NOC 3 18
19 public function area() {}
NOM 4 20 }
21
22 ?>

19. #phpday
phploc
http://sebastianbergmann.github.com/phploc/

20. #phpday

21. #phpday
Complexity

22. Complexity
#phpday
Control Structures Complexity
if, elseif, for, while, foreach, catch, case, xor,
and, or, &&, ||, ?:
Ciclomatic Complexity (CCN)
NPath Complexity

23. Ciclomatic Complexity
1 <?php
2
# decision points 3 class polygon {
4
5 public function perimeter()
6 {
#phpday CCN 7 if (!is_array($this->vertices)) {
8 return false;
9 }
10
11 $perimeter = 0;
12
13 foreach ($this->vertices as $vertex) {
14 $perimenter += $vertex;
15 }
16
17 return $perimeter;
18 }
19 }
20 ?>

24. Ciclomatic Complexity
1 <?php
2
# decision points 3 class polygon {
4
5 public function perimeter()
6 {
#phpday CCN 1 7 if (!is_array($this->vertices)) {
8 return false;
9 }
10
11 $perimeter = 0;
12
13 foreach ($this->vertices as $vertex) {
14 $perimenter += $vertex;
15 }
16
17 return $perimeter;
18 }
19 }
20 ?>

25. Ciclomatic Complexity
1 <?php
2
# decision points 3 class polygon {
4
5 public function perimeter()
6 {
#phpday CCN 2 7 if (!is_array($this->vertices)) {
8 return false;
9 }
10
11 $perimeter = 0;
12
13 foreach ($this->vertices as $vertex) {
14 $perimenter += $vertex;
15 }
16
17 return $perimeter;
18 }
19 }
20 ?>

26. Ciclomatic Complexity
1 <?php
2
# decision points 3 class polygon {
4
5 public function perimeter()
6 {
#phpday CCN 3 7 if (!is_array($this->vertices)) {
8 return false;
9 }
10
11 $perimeter = 0;
12
13 foreach ($this->vertices as $vertex) {
14 $perimenter += $vertex;
15 }
16
17 return $perimeter;
18 }
19 }
20 ?>

27. Ciclomatic Complexity
1 <?php
2
# decision points 3 class polygon {
4
5 public function perimeter()
6 {
#phpday CCN 4 7 if (!is_array($this->vertices)) {
8 return false;
9 }
10
11 $perimeter = 0;
12
13 foreach ($this->vertices as $vertex) {
14 $perimenter += $vertex;
15 }
16
17 return $perimeter;
18 }
19 }
20 ?>

28. CCN Range Values
#phpday 1 - 4: low
5-7: medium
8-10: high
11+: wtf

29. NPath Complexity
1 <?php
2
# acyclic paths 3 class polygon {
4
5 public function perimeter()
6 {
#phpday NPath 7 if (!is_array($this->vertices)) {
8 return false;
9 }
10
11 $perimeter = 0;
12
13 foreach ($this->vertices as $vertex) {
14 $perimenter += $vertex;
15 }
16
17 return $perimeter;
18 }
19 }
20 ?>

30. NPath Complexity
1 <?php
2
# acyclic paths 3 class polygon {
4
5 public function perimeter()
6 {
#phpday NPath 1 7 if (!is_array($this->vertices)) {
8 return false;
9 }
10
11 $perimeter = 0;
12
13 foreach ($this->vertices as $vertex) {
14 $perimenter += $vertex;
15 }
16
17 return $perimeter;
18 }
19 }
20 ?>

31. NPath Complexity
1 <?php
2
# acyclic paths 3 class polygon {
4
5 public function perimeter()
6 {
#phpday NPath 2 7 if (!is_array($this->vertices)) {
8 return false;
9 }
10
11 $perimeter = 0;
12
13 foreach ($this->vertices as $vertex) {
14 $perimenter += $vertex;
15 }
16
17 return $perimeter;
18 }
19 }
20 ?>

32. NPath Complexity
1 <?php
2
# acyclic paths 3 class polygon {
4
5 public function perimeter()
6 {
#phpday NPath 3 7 if (!is_array($this->vertices)) {
8 return false;
9 }
10
11 $perimeter = 0;
12
13 foreach ($this->vertices as $vertex) {
14 $perimenter += $vertex;
15 }
16
17 return $perimeter;
18 }
19 }
20 ?>

33. NPath Complexity
1 <?php
2
# acyclic paths 3 class polygon {
4
5 public function perimeter()
6 {
#phpday NPath 4 7 if (!is_array($this->vertices)) {
8 return false;
9 }
10
11 $perimeter = 0;
12
13 foreach ($this->vertices as $vertex) {
14 $perimenter += $vertex;
15 }
16
17 return $perimeter;
18 }
19 }
20 ?>

34. NPath Treshold
#phpday
Critical if > 200

35. #phpday
PHP Depend
http://pdepend.org

36. #phpday

37. Overview Pyramid
#phpday

38. #phpday
OO Metrics

39. Afferent/Efferent Coupling
#phpday
Ca: no. of unique incoming dependencies
Ce: no. of unique outgoing dependencies

40. Afferent/Efferent Coupling
Shape
area()
#phpday
Circle Triangle
area() area()
Math
PI

41. Afferent/Efferent Coupling
Shape
area()
#phpday
Circle Triangle
area() area()
Math Ca: 1
PI Ce: 0

42. Afferent/Efferent Coupling
Shape
area()
#phpday
Ca: 0 Circle Triangle
Ce: 2 area() area()
Math Ca: 1
PI Ce: 0

43. Afferent/Efferent Coupling
Shape Ca: 2
area() Ce: 0
#phpday
Ca: 1 Circle Triangle
Ce: 1 area() area()
Math Ca: 1
PI Ce: 0

44. Afferent/Efferent Coupling
Shape Ca: 2
area() Ce: 0
#phpday
Ca: 1 Circle Triangle Ca: 0
Ce: 1 area() area() Ce: 1
Math Ca: 1
PI Ce: 0

45. #phpday
$ pdepend --jdepend-chart=j.png .

46. Instability Chart
#phpday
A = AC / (CC + AC)
D = | A + I | -1
I = Ce / (Ce + Ca)

47. #phpday
PHP MD
http://phpmd.org

48. PHP MD
#phpday Code Size Rules
Design Rules
Naming Rules
Unused Code Rules

49. #phpday $ phpmd src/ xml
codesize,design,naming,unusedcode --
reportfile pmd.xml

50. #phpday

51. #phpday
Non Static Analysis

52. C.R.A.P
Change Risk Analysis Predictions or
#phpday
“Your code is crap”
CRAP = CCN^2 * (1 – COV/100)^3 + CCN

53. #phpday
Putting it all together

54. #phpday
PHP_CodeBrowser
https://github.com/mayflowergmbh/PHP_CodeBrowser.git

55. $ phpcb --log logs --source src --output
#phpday
code-browser

56. #phpday
PHP Project Wizard
https://github.com/sebastianbergmann/php-project-wizard.git

57. Code Metrics as a mean to expose
#phpday
internal quality

58. Further Reading
http://manuel-pichler.de/
#phpday
http://pdepend.org
http://phpmd.org
http://www.artima.com/weblogs/viewpost.jsp?thread=215899

59. Questions?
@_orso_
#phpday
mo@ideato.it
http://joind.in/2989