The document discusses principles for choosing good names in code. It recommends that names be pronounceable, avoid encodings, be intention-revealing, and use a ubiquitous language. It provides examples of good and bad variable names and explains why names like "sVal" are bad because they don't convey meaning on their own. The document emphasizes that names are important because they promote understanding of code when read aloud or by others on a team.

1. Simple Design
Declan Whelan
@dwhelan

2. Simple Design
Declan Whelan
@dwhelan

4. “Scrum is not a process or
a technique for building products;
rather, it is a framework within
which you can employ various
processes and techniques.”
Scrum Guide

5. www.XProgramming.com
red circle contains requirementsred circle contains requirements
green circle crates a container to
enable inner practices to be
successful
green circle crates a container to
enable inner practices to be
successful
day-to-day engineering practicesday-to-day engineering practices

8. Engineering Practices Matter

9. Simple Design

10. Simple Design
TestedTested
ClearClear
DryDry
SuccinctSuccinct

11. Simple Design
TestedTested
ClearClear
DryDry
SuccinctSuccinct

12. What is TDD?
• Simple, high-feedback
incremental coding technique
• Write tests as specs, prior
to code
• Immediate feedback from
test execution

13. TDD Rules
1.Test everything that could possibly
break.
2.Do not write any production code
until you have written the code that
will test it.
3.Code is not checked in until all unit
tests pass.

14. TDD Rhythm

15. Exercise

16. public static List<SelectOption> createEndDaysList() { List<SelectOption>
daysList = new ArrayList<SelectOption>(); Date dt = getCurrentDatePlus14Days();
int day = getDateDay(dt); for (int intLooper = 1; intLooper <= 31; intLooper++)
{ SelectOption option = new SelectOption(); if (day == intLooper) {
option.setLabel(String.valueOf(intLooper));
option.setValue(String.valueOf(intLooper)); option.setSelected(true);
} else { option.setLabel(String.valueOf(intLooper));
option.setValue(String.valueOf(intLooper)); option.setSelected(false);
} daysList.add(option); } return daysList;}public static
List<SelectOption> createEndMonthList(Date expiryDate) { List<SelectOption>
monthList = new ArrayList<SelectOption>(); int month = getDateMonth(expiryDate);
for (int intLooper = 1; intLooper <= 12; intLooper++) { SelectOption option
= new SelectOption(); if (month == intLooper)
{ option.setLabel(String.valueOf(intLooper));
option.setValue(String.valueOf(intLooper)); option.setSelected(true);
} else { option.setLabel(String.valueOf(intLooper));
option.setValue(String.valueOf(intLooper)); option.setSelected(false);
} monthList.add(option); } return monthList;}
public static List<SelectOption> createEndDaysList() { List<SelectOption>
daysList = new ArrayList<SelectOption>(); Date dt = getCurrentDatePlus14Days();
int day = getDateDay(dt); for (int intLooper = 1; intLooper <= 31; intLooper++)
{ SelectOption option = new SelectOption(); if (day == intLooper) {
option.setLabel(String.valueOf(intLooper));
option.setValue(String.valueOf(intLooper)); option.setSelected(true);
} else { option.setLabel(String.valueOf(intLooper));
option.setValue(String.valueOf(intLooper)); option.setSelected(false);
} daysList.add(option); } return daysList;}public static
List<SelectOption> createEndMonthList(Date expiryDate) { List<SelectOption>
monthList = new ArrayList<SelectOption>(); int month = getDateMonth(expiryDate);
for (int intLooper = 1; intLooper <= 12; intLooper++) { SelectOption option
= new SelectOption(); if (month == intLooper)
{ option.setLabel(String.valueOf(intLooper));
option.setValue(String.valueOf(intLooper)); option.setSelected(true);
} else { option.setLabel(String.valueOf(intLooper));
option.setValue(String.valueOf(intLooper)); option.setSelected(false);
} monthList.add(option); } return monthList;}
• Find a Partner
• Write pseudo code for tests
you would write

17. Simple Design
TestedTested
ClearClear
DryDry
SuccinctSuccinct

18. Exercise

19. Stroop Effect
Green Red Blue
Purple Blue Purple
Blue Purple Red
Green Purple Green
The Stroop Effect
first set of words is easy to
comprehend.
takes people much longer for
people to comprehend the
correct meaning in the second
case
The Stroop Effect
first set of words is easy to
comprehend.
takes people much longer for
people to comprehend the
correct meaning in the second
case
“semantic interference” where
naming is incongruent with
meaning.
“semantic interference” where
naming is incongruent with
meaning.
This is because of “semantic
facilitation” where name is
congruent with meaning.
- people much faster at naming
the ink color
This is because of “semantic
facilitation” where name is
congruent with meaning.
- people much faster at naming
the ink color
IDE’s leverage this with syntax
colouring.
IDE’s leverage this with syntax
colouring.
Green Red Blue
Purple Blue Purple

20. black
yellow
Meaning:
Colour:
1. look at top and understand its
meaning
2. look at actual coluor
MATCH - if ink colour of bottom
word matches word at top
NOMATCH
1. look at top and understand its
meaning
2. look at actual coluor
MATCH - if ink colour of bottom
word matches word at top
NOMATCH

21. blue
black
Meaning:
Colour:

22. black
yellow

23. yellow
red

24. red
yellow

25. red
yellow

26. blue
blue

27. yellow
blue

28. red
red

29. blue
red

30. yellow
yellow

31. red
yellow

32. red
yellow

33. blue
black

34. yellow
black

35. black
blue

36. red
black

37. The
End
Debrief:
any change as you went longer?
any easier - maybe a little but
still very tiring.
Debrief:
any change as you went longer?
any easier - maybe a little but
still very tiring.
This is like reading code when you
read code and the names of things
are incongruent with their meaning,
We have to keep reminding ourselves
‘oh yeah this is the Foo class and it
actually does Bar”
This is like reading code when you
read code and the names of things
are incongruent with their meaning,
We have to keep reminding ourselves
‘oh yeah this is the Foo class and it
actually does Bar”
Its WAY harder to understand
code that has poorly chosen
names.
Its WAY harder to understand
code that has poorly chosen
names.
We have to choose a lot names
esp. with trends towards smaller
classes and methods.
We have to choose a lot names
esp. with trends towards smaller
classes and methods.
A lot of value in putting energy
into names
A lot of value in putting energy
into names

38. Choosing Good NamesChoosing Good Names

39. Choosing Good NamesChoosing Good Names
Use the telephone test for readability.
If someone could understand your code
when read aloud over the telephone, it's
clear enough.
If not, then it needs rewriting.

40. Telephone TestTelephone Test
Goal Donor vs Gold Owner
Date genymdhmsWe want to promote conversation
about code.
We want to promote conversation
about code.

41. Pronounceable Names
Avoid Encodings
Choosing Good NamesChoosing Good Names

42. UpdatePerfIndValueDecCountCmd
Pronounceable Names

43. UpdatePerfIndValueDecCountCmd
DecrementAggregateCommand
Pronounceable Names

44. Date genymdhms
Pronounceable Names

45. Date genymdhms
Date generatedTimestamp
Pronounceable Names

46. LPSTR lpCmdLine
m_name
Avoid Encodings
LPSTR commandLine
name
Used to make sense.
IDEs now help with type and scope
- don’t need to have names reflect
types.
Used to make sense.
IDEs now help with type and scope
- don’t need to have names reflect
types.
Not so important to embed types or scope
information in the variable.
IDEs help
Not such a problem with small names.
Not so important to embed types or scope
information in the variable.
IDEs help
Not such a problem with small names.

47. Choosing Good NamesChoosing Good Names
Intention-Revealing
Name
Role-Suggesting NamePattern to guide each decision.
Derived a pattern for each
programming decision he made.
Pattern to guide each decision.
Derived a pattern for each
programming decision he made.

48. Intention-Revealing Name
applyMeasureConstraintTo
EnableSortingByMeasure()
Think about method names based on how they will look in calling code.
Why was this method invoked and not some other? That is a question
that can profitably be answered by the name of the method. The calling
method should be telling a story. Name methods so they help tell that
story.
Kent Beck - pg 79
Think about method names based on how they will look in calling code.
Why was this method invoked and not some other? That is a question
that can profitably be answered by the name of the method. The calling
method should be telling a story. Name methods so they help tell that
story.
Kent Beck - pg 79

49. Intention-Revealing Name
applyMeasureConstraintTo
EnableSortingByMeasure()
applyMeasureConstraint()

50. Role-Suggesting Name
int result
IndexCardPageLayout sut

51. Choosing Good NamesChoosing Good Names
Ubiquitous Language
If we start using different words
we are bound to change the code
to match our language.
If we start using different words
we are bound to change the code
to match our language.
Use names from the problem and
solution domain.
Use names from the problem and
solution domain.

52. CComBstr sVal
Ubiquitous Language

53. CComBstr sVal
CComBstr calibrationToolName
Ubiquitous Language
sVal is terrible.
s implies String which I already know from
CComBstr
every variable has a value so Val in name is useless
sVal is terrible.
s implies String which I already know from
CComBstr
every variable has a value so Val in name is useless
People are dropping sophisticated tools to
measure things in drilled wells.
They calibrate these tools and these tools
have name - that’s what that is
People are dropping sophisticated tools to
measure things in drilled wells.
They calibrate these tools and these tools
have name - that’s what that is
Having bad names in code is costlyHaving bad names in code is costly

54. Rx rx
Ubiquitous Language
Ask participants!Ask participants! Healthwatch for a pharmacy
chain.
Had pharmacists on the team and
Rx is the term they would use.
Healthwatch for a pharmacy
chain.
Had pharmacists on the team and
Rx is the term they would use.
Could be better in terms of role
playing ..
e.g. refillable
Could be better in terms of role
playing ..
e.g. refillable
People need to know the domain.
The code, via ubiquitous language,
helps the team learn the domain
People need to know the domain.
The code, via ubiquitous language,
helps the team learn the domain

55. Rx rx
Rx refillable
Ubiquitous Language

56. applyPhq9DateRangeConstraint()
Ubiquitous Language
The PHQ-9 is the nine item depression scale of
the Patient Health Questionnaire.
The PHQ-9 is a powerful tool for assisting
primary care clinicians in diagnosing depression as
well as selecting and monitoring treatment.

57. public List<int[]> getThem() {
List<int[]> list1 = new ArrayList<int[]>();
for (int[] x : theList)
if (x[0] == 4)
list1.add(x);
return list1;
}
Source: Clean Code: A Handbook of Agile Software Craftsmanship, Robert C. Martin, pages 18-19
The complexity here is not in the
code. The complexity is accidental
driven by the names used.
The complexity here is not in the
code. The complexity is accidental
driven by the names used.
Choosing Good NamesChoosing Good Names

58. public List<int[]> getFlaggedCells() {
List<int[]> flaggedCells = new ArrayList<int[]>();
for (int[] cell : gameBoard)
if (cell[STATUS_VALUE] == FLAGGED)
flaggedCells.add(cell);
return flaggedCells;
}
public List<int[]> getThem() {
List<int[]> list1 = new ArrayList<int[]>();
for (int[] x : theList)
if (x[0] == 4)
list1.add(x);
return list1;
}
Source: Clean Code: A Handbook of Agile Software Craftsmanship, Robert C. Martin, pages 18-19
Ubiquitous language
Using names
Ubiquitous language
Using names
Choosing Good NamesChoosing Good Names

59. public List<Cell> getFlaggedCells() {
List<Cell> flaggedCells = new ArrayList<Cell>();
for (Cell cell : gameBoard)
if (cell.isFlagged())
flaggedCells.add(cell);
return flaggedCells;
}
public List<int[]> getThem() {
List<int[]> list1 = new ArrayList<int[]>();
for (int[] x : theList)
if (x[0] == 4)
list1.add(x);
return list1;
}
Source: Clean Code: A Handbook of Agile Software Craftsmanship, Robert C. Martin, pages 18-19
Choosing Good NamesChoosing Good Names

60. public List<Cell> getFlaggedCells() {
List<Cell> result = new ArrayList<Cell>();
for (Cell cell : gameBoard)
if (cell.isFlagged())
result.add(cell);
return result;
}
public List<int[]> getThem() {
List<int[]> list1 = new ArrayList<int[]>();
for (int[] x : theList)
if (x[0] == 4)
list1.add(x);
return list1;
}
Source: Clean Code: A Handbook of Agile Software Craftsmanship, Robert C. Martin, pages 18-19
Mention use of ‘each’Mention use of ‘each’
Choosing Good NamesChoosing Good Names

61. Exercise

62. public static List<SelectOption> createEndDaysList() { List<SelectOption>
daysList = new ArrayList<SelectOption>(); Date dt = getCurrentDatePlus14Days();
int day = getDateDay(dt); for (int intLooper = 1; intLooper <= 31; intLooper++)
{ SelectOption option = new SelectOption(); if (day == intLooper) {
option.setLabel(String.valueOf(intLooper));
option.setValue(String.valueOf(intLooper)); option.setSelected(true);
} else { option.setLabel(String.valueOf(intLooper));
option.setValue(String.valueOf(intLooper)); option.setSelected(false);
} daysList.add(option); } return daysList;}public static
List<SelectOption> createEndMonthList(Date expiryDate) { List<SelectOption>
monthList = new ArrayList<SelectOption>(); int month = getDateMonth(expiryDate);
for (int intLooper = 1; intLooper <= 12; intLooper++) { SelectOption option
= new SelectOption(); if (month == intLooper)
{ option.setLabel(String.valueOf(intLooper));
option.setValue(String.valueOf(intLooper)); option.setSelected(true);
} else { option.setLabel(String.valueOf(intLooper));
option.setValue(String.valueOf(intLooper)); option.setSelected(false);
} monthList.add(option); } return monthList;}
public static List<SelectOption> createEndDaysList() { List<SelectOption>
daysList = new ArrayList<SelectOption>(); Date dt = getCurrentDatePlus14Days();
int day = getDateDay(dt); for (int intLooper = 1; intLooper <= 31; intLooper++)
{ SelectOption option = new SelectOption(); if (day == intLooper) {
option.setLabel(String.valueOf(intLooper));
option.setValue(String.valueOf(intLooper)); option.setSelected(true);
} else { option.setLabel(String.valueOf(intLooper));
option.setValue(String.valueOf(intLooper)); option.setSelected(false);
} daysList.add(option); } return daysList;}public static
List<SelectOption> createEndMonthList(Date expiryDate) { List<SelectOption>
monthList = new ArrayList<SelectOption>(); int month = getDateMonth(expiryDate);
for (int intLooper = 1; intLooper <= 12; intLooper++) { SelectOption option
= new SelectOption(); if (month == intLooper)
{ option.setLabel(String.valueOf(intLooper));
option.setValue(String.valueOf(intLooper)); option.setSelected(true);
} else { option.setLabel(String.valueOf(intLooper));
option.setValue(String.valueOf(intLooper)); option.setSelected(false);
} monthList.add(option); } return monthList;}
• Find a Partner
• Highlight names you would improve
• Write a better name
interloper :)

63. Simple Design
TestedTested
ClearClear
DryDry
SuccinctSuccinct

65. DRY: Don’t Repeat Yourself
Every piece of knowledge must have a
single, unambiguous, authoritative
representation within a system.
Avoiding Duplicate CodeAvoiding Duplicate Code

66. Once and Only Once
Data, structure, or logic should exist
in only one place in the system.
Avoiding Duplicate CodeAvoiding Duplicate Code

67. Test-Driven Development
1.Write new code only if an
automated test has failed.
2.Eliminate duplication.
Avoiding Duplicate CodeAvoiding Duplicate Code

68. Single Choice Principle
Whenever a software system must
support a set of alternatives, one and
only one module in the system should
know their exhaustive list.
Avoiding Duplicate CodeAvoiding Duplicate Code

69. Duplication may be the root
of all evil in software.
Avoiding Duplicate CodeAvoiding Duplicate Code

70. Copy & Paste

71. function something() {
}

72. function something() {
}
function something() {
}

73. function somethingElse() {
}
function something() {
}

74. function somethingElse() {
}
function something() {
}

75. Duplicate Code
Copy & Paste
☞ Duplicate Code
Edit the Copy

76. Duplicate Code
Avoid duplication by expressing
commonality and variability
explicitly.

77. function somethingElse() {
}
function something() {
}

78. Exercise

79. Can you spot the duplicate code?
How would you make the
commonality and variation
explicit?
Can you spot the
commonality and variation?

81. public static List<SelectOption> createEndMonthList(Date expiryDate) { int
selectedMonth = getDateMonth(expiryDate); SelectOptionsSource months = new
SelectOptionsSource(1, 12, selectedMonth); SelectOptions monthOptions = new
SelectOptions(months); return monthOptions.create();}public static List<SelectOption>
createEndDaysList() { int selectedDay = getDateDay(getCurrentDatePlus14Days());
SelectOptionsSource days = new SelectOptionsSource(1, 31, selectedDay); SelectOptions
dayOptions = new SelectOptions(days); return dayOptions.create();}public static
List<SelectOption> createEndYearList() { int selectedYear =
getDateYear(getCurrentDatePlus14Days()); SelectOptionsSource years = new
SelectOptionsSource(1985, 1985 + 30, selectedYear); SelectOptions yearOptions = new
SelectOptions(years); return yearOptions.create();}
public static List<SelectOption> createEndMonthList(Date expiryDate) { int
selectedMonth = getDateMonth(expiryDate); SelectOptionsSource months = new
SelectOptionsSource(1, 12, selectedMonth); SelectOptions monthOptions = new
SelectOptions(months); return monthOptions.create();}public static List<SelectOption>
createEndDaysList() { int selectedDay = getDateDay(getCurrentDatePlus14Days());
SelectOptionsSource days = new SelectOptionsSource(1, 31, selectedDay); SelectOptions
dayOptions = new SelectOptions(days); return dayOptions.create();}public static
List<SelectOption> createEndYearList() { int selectedYear =
getDateYear(getCurrentDatePlus14Days()); SelectOptionsSource years = new
SelectOptionsSource(1985, 1985 + 30, selectedYear); SelectOptions yearOptions = new
SelectOptions(years); return yearOptions.create();}

82. public static List<SelectOption> createEndMonthList(Date expiryDate) { int
selectedMonth = getDateMonth(expiryDate); SelectOptionsSource months = new
SelectOptionsSource(1, 12, selectedMonth); SelectOptions monthOptions = new
SelectOptions(months); return monthOptions.create();}public static List<SelectOption>
createEndDaysList() { int selectedDay = getDateDay(getCurrentDatePlus14Days());
SelectOptionsSource days = new SelectOptionsSource(1, 31, selectedDay); SelectOptions
dayOptions = new SelectOptions(days); return dayOptions.create();}public static
List<SelectOption> createEndYearList() { int selectedYear =
getDateYear(getCurrentDatePlus14Days()); SelectOptionsSource years = new
SelectOptionsSource(1985, 1985 + 30, selectedYear); SelectOptions yearOptions = new
SelectOptions(years); return yearOptions.create();}
public static List<SelectOption> createEndMonthList(Date expiryDate) { int
selectedMonth = getDateMonth(expiryDate); SelectOptionsSource months = new
SelectOptionsSource(1, 12, selectedMonth); SelectOptions monthOptions = new
SelectOptions(months); return monthOptions.create();}public static List<SelectOption>
createEndDaysList() { int selectedDay = getDateDay(getCurrentDatePlus14Days());
SelectOptionsSource days = new SelectOptionsSource(1, 31, selectedDay); SelectOptions
dayOptions = new SelectOptions(days); return dayOptions.create();}public static
List<SelectOption> createEndYearList() { int selectedYear =
getDateYear(getCurrentDatePlus14Days()); SelectOptionsSource years = new
SelectOptionsSource(1985, 1985 + 30, selectedYear); SelectOptions yearOptions = new
SelectOptions(years); return yearOptions.create();}

83. Select Options
Commonality Variability Resolution
Behaviour Collaborator
Encapsulate
Collection

84. Select Options
Commonality Variability Resolution
Data Structure Value of State Simple Java Type

85. Select Options
Encapsulate
Collection

86. Select Options
Parameter
Object

87. Simple Design
TestedTested
ClearClear
DryDry
SuccinctSuccinct

89. Single Responsibility PrincipleSingle Responsibility Principle
There should be one and
only one reason for a class
to change.

90. SRPViolationSRPViolation
if(checkAccess(user)) {
updateEmail(user, email)
}
}
public boolean checkAccess(User user) {
...
}
public boolean updateEmail(User user, String email) {
...
}
}

91. SRP RestoredSRP Restored
if(securityService.checkAccess(user)) {
emailService.updateEmail(user, email)
}
}
public class SecurityService {
public boolean checkAccess(User user) {
...
}
}
public class EmailService {
...
}
}

92. Simple Design
TestedTested
ClearClear
DryDry
SuccinctSuccinct

93. Want More?
Agile Engineering Training KWMarch 17-18, 2015http://bit.ly/aetkw
Use ‘p2p’ for 10% discount

94. Reading
The Elements of Programming Style
Kernighan and Plauger
Prefactoring
Extreme Abstraction Extreme Separation Extreme
Readability
Ken Pugh
Agile in a Flash
Speed-Learning Agile Development
Jeff Langr and Tim Ottinger

95. Reading
Clean Code
A Handbook of Agile Software Craftsmanship
Robert C. Martin
Domain Driven Design
Tackling Complexity in the Heart of Software
Eric Evans
Implementation Patterns
Kent Beck

96. Reading
The Pragmatic Programmer: From Journeyman to MasterA
Extreme Programming Explained: Embrace ChangeKent B
Test Driven Development: By ExampleKent Beck
Object-Oriented Software Construction
Bertrand Meyer

97. Reading
Design Patterns: Elements of Reusable
Object-Oriented Software Erich Gamma,
Richard Helm, Ralph Johnson, and John Vlissides
Multi-Paradigm Design for C++
James O. Coplien
Lean Architecture: for Agile Software Development
James O. Coplien and Gertrud Bjørnvig

98. Photo Credits
http://www.flickr.com/photos/27558040@N00/4151899795/
http://www.flickr.com/photos/popilop/331357312/
http://www.flickr.com/photos/arlette/3260468/
http://www.flickr.com/photos/36829973@N04/3546657245/
http://www.flickr.com/photos/40838054@N00/7261734660/

99. http://www.flickr.com/photos/93617791@N00/1347587396/
http://www.flickr.com/photos/8281413@N06/5070788991/
http://www.flickr.com/photos/23403402@N00/1197947341/
http://www.flickr.com/photos/54087404@N00/4638056301/
http://en.wikipedia.org/wiki/File:Leghold_trap.JPG
http://www.hostingwiththemostzing.com/?p=12
http://www.flickr.com/photos/36829973@N04/3546657245/
Photo Credits

100. http://www.flickr.com/photos/42644641@N07/5702962303/
http://www.flickr.com/photos/44124484001@N01/116962927/
http://www.flickr.com/photos/25509772@N00/2951851296/
http://www.flickr.com/photos/49016492@N08/4534101229/
http://www.flickr.com/photos/44123231@N05/5658726857/
http://www.flickr.com/photos/24367734@N00/46452239/
http://www.flickr.com/photos/17001563@N00/2847422081/
http://www.flickr.com/photos/59707463@N00/1312377396/
Photo Credits

101. http://www.flickr.com/photos/44123231@N05/5658726857/
https://dianedrake.com/wp-content/uploads/2014/06/sisyphus1.png
Photo Credits

102. Diagram Credits
Lisa Crispin and Janet Gregory
Agile Testing: A Practical Guide for Testers
and Agile Teams
Addison-Wesley Professional; January 9, 2009.
Mike Cohn
Succeeding with Agile: Software Development
Using Scrum
Addison-Wesley Professional; November 5, 2009.

103. Diagram Credits
Jim Highsmith
The Financial Implications of Technical Debt
http://jimhighsmith.com/the-financial-implications-of-technical-debt/
Martin Fowler
http://martinfowler.com/bliki/TechnicalDebtQuadrant.html
Jim Highsmith in his article The Financial Implications of Technical Debt, states: