1. Measuring your code
A talk by Nate Abele
@nateabele
nate.abele@gmail.com

2. Feedback
http://joind.in/1601

3. Confession

5. Coercion, red bars & broken
windows

6. Continuous

7. Goal: Perfection

8. Or at the least, continuous
improvement

9. a.k.a. (kaizen)

10. What people usually think
Estimating costs
Projecting deadlines
Managerial BS!

11. Client Spec Sheet some paraphrased)
(actual bullet points,
Flash intro with no load time
User account logins, password optional
Ajax chat
“Like Google”

12. ...and my personal favorite
Social network

13. Measurement is an essential element of
management; there is little chance of
controlling what we can not measure.
- Wikipedia, “Software metric”

14. Wherefore... (WTF) ?

15. “Engineer” & “architect”

17. Cognitive Dissonance *
Engineers deal with tangible, immutable
constraints, like gravity
The practice of developing software is
an inherently creative discipline
* Thank you, Jones

18. Cognitive Dissonance
Developer constraints (scope, schedule,
budget) potentially / often in flux
Software is inter-related; working on one
part changes the others
No project is exactly the same as another

19. Conclusion
It’s not useful to measure high-level,
intangible things like whole projects
This is where scrum comes in handy
Instead, we can use lower-level, more
concrete measurements

20. What can we measure?

21. Code!!

22. More specifically...
Unit test coverage
Complexity
Speed
Documentation

23. More specifically...
Standards conformance
Refactoration!

24. Backing up...
What is a metric?
Measurement assigns numbers based on well-
defined meaning
- Sometimes the environment must be
modified
- Special development procedures that track
various activities - Wikipedia (paraphrased)
You can cheat and use booleans, too

25. Notes on continuous integration
A build system
Runs on every code commit
Runs tests
Reports

26. Metric examples

27. PHP Code Sniffer
PEAR Package:
http://pear.php.net/package/PHP_CodeSniffer
Checks conformance of a set of files against
a series of classes called “sniffs”

28. PHP Code Sniffer
$ phpcs /path/to/code/myfile.php
FILE: /path/to/code/myfile.php
------------------------------------------------------------------------
FOUND 5 ERROR(S) AFFECTING 2 LINE(S)
------------------------------------------------------------------------
2 | ERROR | Missing file doc comment
47 | ERROR | Line not indented correctly; expected 4 spaces but found 1
51 | ERROR | Missing function doc comment
88 | ERROR | Line not indented correctly; expected 9 spaces but found 6
------------------------------------------------------------------------

29. PHP Code Sniffer
$ svn commit -m "Test" temp.php
Sending temp.php
Transmitting file data .svn: Commit failed (details follow):
svn: 'pre-commit' hook failed with error output:
FILE: temp.php
--------------------------------------------------------------
FOUND 1 ERROR(S) AND 0 WARNING(S) AFFECTING 1 LINE(S)
--------------------------------------------------------------
2 | ERROR | Missing file doc comment
--------------------------------------------------------------

30. This is important because things
are standardized

31. Measuring code complexity
Cyclomatic complexity
Directly measures the number of linearly
independent paths through a program's
source code.
a.k.a. 1 + the number of times it branches

32. Measuring code complexity
public function render() {
$code = null;
if (isset($this->headers['location']) && $this->status['code'] === 200) {
$code = 302;
}
if (!$status = $this->status($code)) {
throw new Exception('Invalid status code');
}
$this->_writeHeader($status);
foreach ($this->headers as $name => $value) {
$key = strtolower($name);
if ($key == 'location') {
$this->_writeHeader("Location: {$value}", $this->status['code']);
} elseif ($key == 'download') {
$this->_writeHeader('Content-Disposition: attachment; filename="' . $val
} elseif (is_array($value)) {
$this->_writeHeader(
array_map(function($v) use ($name) { return "{$name}: {$v}"; }, $val
);
} elseif (!is_numeric($name)) {
$this->_writeHeader("{$name}: {$value}");
}
}
}

33. Measuring code coverage

34. Measuring documentation coverage
Check it out @ http://thechaw.com/api_generator

35. Measuring documentation coverage
Check it out:
http://thechaw.com/api_generator
A series of rules
Assigns weights based on docblock content
and various docblock tags

36. Measuring documentation coverage
Basic checks:
Do doc tags exist?
Incomplete @param tags?
Do @param tags match actual params?
Does it have a @link to the man page?

37. Profiling

38. Profiling
Get timing / memory usage on every test run
Granular, get statistics per test method
Using continuous integration, code is profiled
on each commit, all on a granular level

39. Case study

40. CakePHP 1.2 release cycle
1.2 alpha 1.2 beta 1.2 RC1 1.2 RC2 1.2 RC3 1.2 RC4

41. Metrics are your canary in the coal
mine of your development cycle

42. By tracking profiler stats (and other metrics),
we can see trends over time, and catch
problems before they become problems

43. Plus, who doesn’t like pretty graphs?

44. Finding things to measure
Lithium Inspector class
Lithium Parser class
Based on the awesome work of Sean Coates
http://github.com/scoates/tokalizer

45. Finding things to measure

46. Finding things to measure

47. Finding things to measure

48. Finding things to measure

49. Finding things to measure

50. In a dynamic language like PHP, this
is a hard problem.

51. However, deep code introspection
allows us to ask & answer some
very interesting questions

52. Project mess detection in PHPUnit

53. Beyond copy-paste detection & into
pattern recognition

54. High-level refactoring tools

55. Can “good code” be quantified??

56. When is “good enough”... good enough?

57. Technical debt

58. Incentives and social coercion

59. Choose your own adventure!

60. Go write better code