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![N-path Complexity
// …
$count['staticMethods'],
$count['methods'] > 0 ? ($count['staticMethods'] / $count['methods']) * 100 : 0,
$count['publicMethods'],
$count['methods'] > 0 ? ($count['publicMethods'] / $count['methods']) * 100 : 0,
$count['nonPublicMethods'],
$count['methods'] > 0 ? ($count['nonPublicMethods'] / $count['methods']) * 100 : 0,
$count['functions'],
$count['namedFunctions'],
$count['functions'] > 0 ? ($count['namedFunctions'] / $count['functions']) * 100 : 0,
// …](https://image.slidesharecdn.com/measuringmaintainability-150812082324-lva1-app6892/85/Measuring-maintainability-software-metrics-explained-33-320.jpg)
Uploaded byDennis de Greef
Measuring maintainability; software metrics explained
The document discusses methods for measuring software maintainability, focusing on metrics such as lines of code, cyclomatic complexity, and coupling. It provides definitions and calculations for various metrics, emphasizes that such statistics should not be used as the sole indicators of quality, and highlights tools like PHPLoc for analysis. The presentation encourages understanding code structure and complexity to improve software design and maintainability.
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Measuring maintainability; software metrics explained
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- 2. Dennis de Greef SoftwareDeveloper at TransIP Meetup addict Tech enthousiast Occasional speaker Bass player Domotica Software architect Hardware hacker Infrastructure engineer
- 3. Talk roadmap - Aboutstatic software analysis - Measuring lines of code - Measuring complexity - Measuring coupling
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- 6. How many linesof code? 1 <?php 2 3 /* this is a for-loop */ 4 for ($i = 0; $i < 100; $i++) 5 { 6 printf("hello"); 7 }
- 7. How many linesof code? 1 <?php 2 3 /** 4 * This is a for-loop 5 */ 6 for ($i = 0; $i < 100; $i++) printf("hello");
- 8. Depends on yourdefinition
- 10. LOC: Physical linesof code LLOC: Logical lines of code CLOC: Comment lines of code NCLOC: Non-comment lines of code Different types:
- 11. How many linesof code? 7 physical lines of code 3 logical lines of code 1 comment lines of code 6 non-comment lines of code 1 <?php 2 3 /* this is a for-loop */ 4 for ($i = 0; $i < 100; $i++) 5 { 6 printf("hello"); 7 }
- 12. How many linesof code? 6 physical lines of code 3 logical lines of code 3 comment lines of code 3 non-comment lines of code 1 <?php 2 3 /** 4 * This is a for-loop 5 */ 6 for ($i = 0; $i < 100; $i++) printf("hello");
- 13. Some statistics LOC Physical CLOC Comment NCLOC Non-Comment LLOC Logical symfony-standard 371490 102161 (27.50%) 269329 (72.50%) 84262 (22.68%) zend-framework2306097 112498 (36.75%) 193599 (63.25%) 56053 (18.31%) laravel-framework 78191 35156 (44.96%) 43035 (55.04%) 11970 (15.31%) cakephp 93455 42454 (45.43%) 51001 (54.57%) 17235 (18.44%) phploc 2.1.2-17-gb6bfd40 PSR-2 PSR-2 PSR-2 PSR-2
- 14. WARNING! Don’t use thesestatistics as a form of measuring quality or productivity! People will just ‘game’ the system *applies different codestyle*
- 16. Use it togain more insight about the application “Measuring programming progress by lines of code is like measuring aircraft building progress by weight.” --Bill Gates
- 17. composer require phploc/phploc $phploc loc1.php phploc 2.0.2 by Sebastian Bergmann. ! Size Lines of Code (LOC) 7 Comment Lines of Code (CLOC) 1 (14.29%) Non-Comment Lines of Code (NCLOC) 6 (85.71%) Logical Lines of Code (LLOC) 3 (42.86%) Classes 0 (0.00%) Average Class Length 0 Average Method Length 0 Functions 0 (0.00%) Average Function Length 0 Not in classes or functions 3 (100.00%)
- 18. Measuring Complexity • CyclomaticComplexity • N-path Complexity Complexity and quality are strongly related
- 19. Cyclomatic Complexity “It isa quantitative measure of the number of linearly independent paths through a program's source code.” M = E − N + 2P E = the number of edges of the graph. N = the number of nodes of the graph. P = the number of connected components. http://www.literateprogramming.com/mccabe.pdf
- 21. Simply put: Counting ofdecision trees: - function - for(each) - while - if - case
- 22. Cyclomatic Complexity 1 <?php 2 3function foo($a, $b) { 4 if($a) { 5 if($b) { 6 echo "Hello World"; 7 } 8 } 9 } 10 5 edges 4 nodes 1 compound M = 5 − 4 + 2x1 = 3 M = E − N + 2P
- 23. Cyclomatic Complexity 8 edges 7nodes 1 compound M = 8 − 7 + 2x1 = 3 M = E − N + 2P 1 <?php 2 3 function foo() { 4 if($a) { 5 echo '1'; 6 } else { 7 echo '2'; 8 } 9 if($b) { 10 echo '3'; 11 } else { 12 echo '4'; 13 } 14 }
- 24. Cyclomatic Complexity How manytests do we need? M = 8 − 7 + 2x1 = 3 Complete branch coverage: foo(true, false) foo(false, true)
- 25. Code Coverage 1 <?php 2 3function foo($a, $b) { 4 if($a) { 5 // ... 6 } 7 8 if($b) { 9 // ... 10 } 11 } 12 13 foo(true, false); 14 foo(false, true); All paths are tested with these two function calls. This implies 100% code coverage. ! Or does it? What about: foo(false, false) foo(true, true) ?
- 26. Code Coverage Path coverage: http://derickrethans.nl/path-branch-coverage.html Xdebug2.3.0 PHP_CodeCoverage: not supported
- 27. N-path Complexity “The NPathcomplexity of a method is the number of acyclic execution paths through that method.”
- 28. “The NPath complexityof a method is the number of acyclic execution paths through that method.” N-path Complexity
- 29. “The NPath complexityof a method is the number of acyclic execution paths through that method.” N-path Complexity
- 30. N-path Complexity Path coverage M= E − N + 2P E = the number of edges of the graph. N = the number of nodes of the graph. P = the number of connected components.
- 31. N-path Complexity foo(false, false) foo(true,false) foo(false, true) foo(true, true) Cyclomatic Complexity = 3 N-path Complexity = 4 N-path is exponential
- 32. N-path Complexity foo(false, false) foo(true,false) foo(false, true) foo(true, true) Cyclomatic Complexity = 3 N-path Complexity = 4 N-path is exponential Number of unique paths
- 33. N-path Complexity // … $count['staticMethods'], $count['methods']> 0 ? ($count['staticMethods'] / $count['methods']) * 100 : 0, $count['publicMethods'], $count['methods'] > 0 ? ($count['publicMethods'] / $count['methods']) * 100 : 0, $count['nonPublicMethods'], $count['methods'] > 0 ? ($count['nonPublicMethods'] / $count['methods']) * 100 : 0, $count['functions'], $count['namedFunctions'], $count['functions'] > 0 ? ($count['namedFunctions'] / $count['functions']) * 100 : 0, // …
- 34. N-path Complexity The methodprintResult() has an NPath complexity of 47683715820312500. The configured NPath complexity threshold is 200.
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- 37. Measuring Coupling Coupling betweenpackages Packages being either a namespace or composer package
- 38. Measuring Coupling Afferent Coupling(Ca):" Amount of other packages depending on this class (incoming) ! Efferent Coupling (Ce):" Amount of dependencies of this class ! Instability (I):" Resilience to change, metric between 0 and 1. Where 0 is stable. I = Ce / (Ce + Ca)
- 39. Measuring Coupling Ca =2 Ce = 3 I = Ce / (Ce + Ca) I = 3 / (3+2) I = 0,6 I = 0,0 = Completely stable I = 1,0 = Completely unstable
- 40. Measuring Coupling Abstract:" Either anabstract class or interface ! Concrete:" Any class that is neither abstract or final ! Abstractness (A):" How abstract a package is, ratio between 0 and 1. Where 0 is concrete. A = Abstract / (Abstract + Concrete)
- 41. Measuring Coupling PHPMD (PHPMess Detector) Can detect (code size rules): - Cyclomatic complexity - N-path complexity - Excessive method length - Too many methods - etcetera 10 200 100 10 And other things - Clean Code - Design Rules - Naming Rules - Unused Code Rules
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- 44. Thank youBig thanksto: ! Derick Rethans (Xdebug) Sebastian Bergmann" (PHPLOC, PHPunit, PHP_CodeCoverage) Thomas J. McCabe Sr: Cyclomatic Complexity Robert C. Martin: Lots of things! (nicknamed ‘Uncle Bob’) ! Many more… Twitter: @dennisdegreef Blog: dennisdegreef.net IRC (Freenode): link0 Github: dennisdegreef / link0 PHPNL-Slack: link0 Joind.in: https://joind.in/14991