We use static code analysis tools more often these days that create great reports and funky graphs. But do we understand what it all means? Software metrics tends to be magic numbers for a lot of people, but they don’t really have to be. Seb will introduce you to a few basic, the most popular software metrics and tools. He will explain to you what they mean and how you can use them to produce better software.

1. Magic
behind
the
numbers
So.ware
metrics
in
prac&ce
Sebas&an
Marek,
So.ware
Architect

2. • a
Pole
living
in
Sheffield
• over
12
years
in
development
• Pascal,
C++,
PHP,
perl,
python,
Java
• co-­‐author
of
2
PHP
books
• big
fan
of
process
automa&on
• TDD
and
CI
• occasionally
contributes
to
open
source
projects
• wants
to
be
a
knight
@proofek

3. • What
I
will
be
talking
about
• Code
metrics
• Design
metrics
• What
I
will
not
be
talking
about
• Project
metrics
Agenda

4. Most
effec&ve
code
quality
measure

6. “It is the mapping of
a particular
characteristic
of a measured entity
to a numerical value”
Source: Object-Oriented Metrics
in Practice
What
is
a
metric?

7. “Good design quality metrics are not
necessarily indicative of good designs.
Likewise, bad design quality metrics are
not necessarily indicative of bad
designs”
Source: Jdepend Docs
So.ware
design

8. • Obsolete
documenta&on
• Convoluted
design
• Intensive
patch
mechanism
(hacking)
• Large
size
• Severe
duplica&on
• Obsolete
parts
(dead
code)
• Long
build
&mes
• Loss
of
original
developers
System
maintenance

9. • CLOC
–
comment
lines
of
code
• ELOC
–
executable
lines
of
code
• LOC
–
lines
of
code
• NCLOC
–
non
comment
lines
of
code
• NOP
–
number
of
packages
• NOC
–
number
of
classes
• NOM
–
number
of
methods
Simple
metrics

10. Cyclomatic complexity measures
the amount of decision logic
in a single software module
Cycloma&c
Complexity
(CYCLO)

11. Condi3onal
statements:
• ?
• case
• elseif
• for
• foreach
• if
• while
Cycloma&c
Complexity
Number
(CCN)

12. Condi3onal
statements:
• ?
• &&
• case
• ||
• elseif
• for
• or
• foreach
• and
• if
• xor
• while
CCN2

13. Condi3onal
statements:
• ?
• &&
• case
• ||
• elseif
• for
• or
• foreach
• and
• if
• xor
• while
• catch
Cycloma&c
Complexity

14. class Foo {
public function example() {
if ($a == $b) {
if ($a1 == $b1) {
fiddle();
} elseif ($a2 == $b2) {
fiddle();
} else {
fiddle();
}
} elseif ($e == $f) {
for ($n = 0; $n < $h; $n++) {
fiddle();
}
} else {
fiddle();
}
}
}
Cycloma&c
complexity
-­‐
example

15. class Foo {
public function example() { 1
if ($a == $b) { 2
if ($a1 == $b1) { 3
fiddle();
} elseif ($a2 == $b2) { 4
fiddle();
} else {
fiddle();
}
} elseif ($e == $f) { 5
for ($n = 0; $n < $h; $n++) { 6
fiddle();
}
} else {
fiddle();
}
}
}
Cycloma&c
complexity
-­‐
example

16. phploc 1.6.1 by Sebastian Bergmann.
Directories: 6
Files: 20
Lines of Code (LOC): 5478
Cyclomatic Complexity / Lines of Code: 0.13
Comment Lines of Code (CLOC): 2143
Non-Comment Lines of Code (NCLOC): 3335
Namespaces: 0
Interfaces: 1
Classes: 18
Abstract: 2 (11.11%)
Concrete: 16 (88.89%)
Average Class Length (NCLOC): 191
Methods: 151
Scope:
Non-Static: 143 (94.70%)
Static: 8 (5.30%)
Visibility:
Public: 116 (76.82%)
Non-Public: 35 (23.18%)
Average Method Length (NCLOC): 22
Cyclomatic Complexity / Number of Methods: 3.72
Anonymous Functions: 0
Functions: 2
Constants: 4
Global constants: 3
Class constants: 1
phploc

17. Low
Avg
High
V.High
Complexity
1-­‐4
5-­‐7
8-­‐10
>
11
Cycloma&c
complexity
-­‐
thresholds

18. Metric
Low
Avg
High
V.High
CYCLO/Line
of
code
0.16
0.20
0.24
0.36
LOC/Method
7
10
13
19.5
NOM/Class
4
7
10
15
Source:
Object-­‐Oriented
Metrics
in
Prac5ce
(based
on
45
Java
projects)
JAVA

19. Metric
Low
Avg
High
V.High
CYCLO/Line
of
code
0.20
0.25
0.30
0.45
LOC/Method
5
10
16
24
NOM/Class
4
9
15
22.5
Source:
Object-­‐Oriented
Metrics
in
Prac5ce
(based
on
37
C++
projects)
C++

20. Weighted
Method
Count
–
total
complexity
of
a
class
Average
Method
Weight
–
average
complexity
of
a
method
WMC
and
AMW

21. Metric
Low
Avg
High
V.High
WMC
5
14
31
47
AMW
1.1
2.0
3.1
4.7
LOC/Class
28
70
130
195
Source:
Object-­‐Oriented
Metrics
in
Prac5ce
(based
on
45
Java
projects)
JAVA

22. Metric
Low
Avg
High
V.High
WMC
4
23
72
108
AMW
1.0
2.5
4.8
7.0
LOC/Class
20
90
240
360
Source:
Object-­‐Oriented
Metrics
in
Prac5ce
(based
on
37
C++
projects)
C++

23. Coverage
report

24. Coverage
report

25. C.R.A.P

26. Change
Risk
Analysis
and
Predic&ons
C.R.A.P

27. Code
coverage
=
100%
Code
coverage
=
0%
C.R.A.P
formula

28. C.R.A.P
thresholds

29. “NPATH is an objective measure of
software complexity related to
the ease with which software
can be comprehensively tested”
Edgar H. Sibley
NPATH
–
acyclic
execu&on
path
complexity

30. expressions Number of && and || operators in expression
if NP(<if-range>)+NP(<expr>)+1
if-else NP(<if-range>)+NP(<else-range>)+NP(<expr>)
while NP(<while-range>)+NP(<expr>)+1
for NP(<for-range>)+NP(<expr1>)+NP(<expr2>)+
NP(<expr3>)+1
break 1
continue 1
return 1
sequential 1
function call 1
NPATH
–
acyclic
execu&on
path
complexity

31. class Foo {
public function example() {
if ($a == $b) {
if ($a1 == $b1) {
fiddle();
} else {
fiddle();
}
}
if ($e == $f && $g == $z) {
for ($n = 0; $n < $h; $n++) {
fiddle();
}
}
return true;
}
}
NPATH
–
example

32. class Foo {
public function example() {
if ($a == $b) {
if ($a1 == $b1) {
fiddle();
} else { 3
fiddle();
}
}
if ($e == $f && $g == $z) {
for ($n = 0; $n < $h; $n++) {
fiddle(); 4
}
}
return true; 1
}
}
NPATH
–
example

33. PHP_Depend 0.10.6 by Manuel Pichler
Parsing source files:
.................... 20
Executing CyclomaticComplexity-Analyzer:
............. 261
Executing ClassLevel-Analyzer:
............ 247
Executing CodeRank-Analyzer:
. 28
Executing Coupling-Analyzer:
............. 267
Executing Hierarchy-Analyzer:
............ 246
Executing Inheritance-Analyzer:
. 30
Executing NPathComplexity-Analyzer:
.............. 283
Executing NodeCount-Analyzer:
........ 174
Executing NodeLoc-Analyzer:
.......... 205
Generating pdepend log files, this may take a moment.
Time: 00:05; Memory: 25.50Mb
PHP
Depend

34. PHP
Mess
Detector

35. Overview
pyramid

36. Size
and
complexity
–
direct
metrics

37. Size
and
complexity
–
computed
propor&ons

38. System
coupling
–
direct
metrics

39. System
coupling
–
computed
propor&ons

40. System
inheritance

41. Complete
Overview
Pyramid

42. Metric
Low
Avg
High
CYCLO/LOC
0.16
0.20
0.24
LOC/NOM
7
10
13
NOM/NOC
4
7
10
NOC/NOP
6
17
26
CALLS/NOM
2.01
2.62
3.2
FANOUT/CALLS
0.56
0.62
0.68
ANDC
0.25
0.41
0.57
AHH
0.09
0.21
0.32
hBp://pdepend.org/
PHP

43. Metrics
visualisa&on
with
Sonar

44. Metrics
visualisa&on
with
Sonar

45. Viola&ons
repor&ng

46. -­‐-­‐
Very
bad
-­‐
Bad
0
Average
+
Good
++
Very
good
SIG
Maintainability
Model

47. Technical
Debt

48. “We
believe
that
soIware
metrics,
in
general,
are
just
tools.
No
single
metric
can
tell
the
whole
story;
it’s
just
one
more
data
point.
“
“Metrics
are
meant
to
be
used
by
developers,
not
the
other
way
around
–
the
metric
should
work
for
you,
you
should
not
have
to
work
for
the
metric.
“
“Metrics
should
never
be
an
end
unto
themselves.
Metrics
are
meant
to
help
you
think,
not
to
do
the
thinking
for
you.”
• Alberto
Savoia
Summary

49. • PHP
Depend
-­‐
hmp://pdepend.org/
• PHP
Mess
Detector
-­‐
hmp://phpmd.org/
• Manuel’s
home
page
-­‐
hmp://manuel-­‐pichler.de/
• PHPUnit
-­‐
hmp://www.phpunit.de/
• phploc
-­‐
hmp://sebas&anbergmann.github.com/phploc/
• Sonar
-­‐
hmp://www.sonarsource.org/
Resources

50. “Object-­‐Oriented
Metrics
in
Prac&ce”
by
Michele
Lanza
and
Radu
Marinescu
(ISBN
978-­‐3540244295)
Object-­‐Oriented
Metrics
in
Prac&ce

51. • hmp://www.flickr.com/photos/romainguy/102073478/
• hmp://www.flickr.com/photos/shanafin/615680234/
• hmp://www.flickr.com/photos/pahudson/3080270873/
• hmp://www.flickr.com/photos/smohundro/2243554264/
• hmp://www.flickr.com/photos/m_a_melendez/5956157581/
• hmp://www.flickr.com/photos/elkit/7182541802/
• hmp://www.flickr.com/photos/rickyromero/4209571303/
Thanks
to…

52. Ques&ons?
hmps://joind.in/6445
Ques&ons?