The document discusses refactoring code through an "inside out" approach. It begins by showing sample code, then discusses strategies and objectives for refactoring like improving design, adding features, and fixing bugs. Specific refactoring techniques are explained like extracting methods, eliminating duplication, and changing design. The presentation emphasizes using tests during refactoring and considering the "big picture" of strategies and mechanics when refactoring large bodies of code. Coding examples are provided to demonstrate refactoring steps.

1. Refactoring at Large
Danilo Sato - @dtsato
ThoughtWorks
www.dtsato.com

6. My Plan for Today
+ • “Inside out” approach
• Show me Code (Java)
• Strategies and Objectives
• Refactoring Ruby/Rails
- • Larger refactorings

8. Why do we change
code?

9. Why do we change
code?
• Add features

10. Why do we change
code?
• Add features
• Fix bugs

11. Why do we change
code?
• Add features
• Fix bugs
• Improve design

12. Why do we change
code?
• Add features
• Fix bugs
• Improve design
• Optimization

13. Why do we change
code?
• Add features
• Fix bugs
• Improve design
• Optimization

17. "Refactoring is a disciplined
technique for restructuring an
existing body of code, altering its
internal structure without
changing its external behavior."

18. Refactoring
Code

19. Refactoring
Code

20. Refactoring
Code
Extr act Method

21. Refactoring
Code

22. Refactoring
Code

23. Refactoring
Code
Eliminate Duplication

24. • Extract Method
• Move Method
• Extract Class
• Remove Middle Man
• Self Encapsulate Field
• Decompose Conditional
• ...

25. Tests!
Code
Test

26. Tests!
Code
Test

27. Tests!
Code
Test
Eliminate Duplication

28. Other types...
Code
Test

29. Other types...
Code Code
Test

30. Other types...
Code Code
Test Test

31. Other types...
Code Code
Test Test
Split Responsibility

32. Other types...
Code
Test

33. Other types...
Test Code

34. Other types...
Test Code

35. Other types...
Test Code
Change Design

36. Even more...

37. “Big Picture”

38. “Big Picture”

39. “Big Picture”

40. “Big Picture”

41. “Big Picture”

42. Strategy
Mechanics

43. Coding Kata!

44. Coding Kata!

45. CheckoutControllerTest CheckoutController
Order Cart

46. -
1 2/10/refactoring
o.com/blog/2011/
http://www.dtsat /
h rough-experiment
st rategies-a-walkt
-
0 9/01/refactoring
http://paulh ammant.com/2011/
experiment
CheckoutControllerTest CheckoutController
Order Cart

47. public class CheckoutControllerTest {
private CheckoutController checkoutController;
private Cart cart = new Cart(); // could as easily be a mock
private Order order = new Order(); // could as easily be a mock
private ModelMap model = new ModelMap();
@Before public void setup() {
checkoutController = new CheckoutController(cart, order);
}
@Test public void checkout_should_add_an_upsell() {
String result = checkoutController.goCheckout(model);
assertThat(result, equalTo("checkout"));
assertThat(model.toString(), equalTo("{cart=Cart{contents=[[iPad]]}}"));
}
@Test public void place_order_in_checkout_should_make_an_order() {
cart.addTo("dummy");
String result = checkoutController.placeOrder(model);
assertThat(result, equalTo("orderPlaced"));
assertThat(model.toString(),
equalTo("{order=Order{cart=Cart{contents=[[dummy]]}}}"));
}
}

48. @Controller public class CheckoutController {
private final Cart cart;
private final Order order;
@Autowired public CheckoutController(Cart cart, Order order) {
this.cart = cart;
this.order = order;
}
@RequestMapping("/go/to/checkout/") public String goCheckout(ModelMap model) {
cart.addTo(findUpsell(cart));
model.addAttribute("cart", cart);
return "checkout";
}
@RequestMapping("/place/order") public String placeOrder(ModelMap model) {
order.place(cart);
model.addAttribute("order", order);
return "orderPlaced";
}
String findUpsell(Cart cart) { return cart.size() == 0 ? "iPad" : "iPod Nano"; }
}

49. Mechanics
t his video on: riment
Watch factoring-expe
com/dt sato/re
p://vimeo.
htt

50. First Attempt...
t his video on: riment
Watch factoring-expe
com/dt sato/re
p://vimeo.
htt

51. Strategy
t his video on: riment
Watch factoring-expe
com/dt sato/re
p://vimeo.
htt

52. Identify your Objective

53. Identify your Objective

54. Identify your Objective
“Active” design

55. Identify your Objective
“Active” design
• OO Design

56. Identify your Objective
“Active” design
• OO Design
• Project direction

57. Identify your Objective
“Active” design
• OO Design
• Project direction
• Architectural decisions

58. Identify your Objective
“Passive” design

59. Identify your Objective
“Passive” design
• Bad Smells

60. Identify your Objective
“Passive” design
• Bad Smells
• Metrics

61. Identify your Objective
“Passive” design
• Bad Smells
• Metrics
• Visualizations

62. Strategize

63. Strategize
? ?
?

64. Strategize

65. Strategize
• Isolate the impact of Change

66. Strategize
• Isolate the impact of Change
• Baby Steps

67. Strategize
• Isolate the impact of Change
• Baby Steps
• Keep the tests green

68. Strategize
• Isolate the impact of Change
• Baby Steps
• Keep the tests green
• Moving backwards before moving forward

69. CalendarSearchController
CalendarSearchController
Test
Event Event

70. r
dtsato/kata-ref actoring-calenda
http ://github.com/
CalendarSearchController
CalendarSearchController
Test
Event Event

71. def index(params)
scope = Event
case params[:timeframe]
when 'tomorrow'
scope = scope.between_day(DateTime.now + 1)
when 'this_week'
scope = scope.between_dates(DateTime.now, ( DateTime.now + 6 ).end_of_day)
when 'custom'
if params[:start_date].blank?
params[:start_date] = DateTime.now.beginning_of_week.strftime('%m/%d/%Y')
end
if params[:end_date].blank?
params[:end_date] = (DateTime.now.end_of_week - 2).strftime('%m/%d/%Y')
end
scope = scope.between_dates(DateTime.strptime(params[:start_date], '%m/%d/%Y'),
DateTime.strptime(params[:end_date], '%m/%d/%Y').end_of_day)
when 'hour'
scope = scope.between_hour_on_day(DateTime.strptime(params[:hour], '%m/%d/%Y %H:
%M'))
when 'today'
scope = scope.between_day(DateTime.now)
end
@events = scope.all
end

72. def index(params)
scope = Event switch/case
case params[:timeframe]
when 'tomorrow'
scope = scope.between_day(DateTime.now + 1)
when 'this_week'
scope = scope.between_dates(DateTime.now, ( DateTime.now + 6 ).end_of_day)
when 'custom'
if params[:start_date].blank?
params[:start_date] = DateTime.now.beginning_of_week.strftime('%m/%d/%Y')
end
if params[:end_date].blank?
params[:end_date] = (DateTime.now.end_of_week - 2).strftime('%m/%d/%Y')
end
scope = scope.between_dates(DateTime.strptime(params[:start_date], '%m/%d/%Y'),
DateTime.strptime(params[:end_date], '%m/%d/%Y').end_of_day)
when 'hour'
scope = scope.between_hour_on_day(DateTime.strptime(params[:hour], '%m/%d/%Y %H:
%M'))
when 'today'
scope = scope.between_day(DateTime.now)
end
@events = scope.all
end

73. def index(params)
scope = Event
case params[:timeframe]
when 'tomorrow'
scope = scope.between_day(DateTime.now + 1)
when 'this_week' string parsing
scope = scope.between_dates(DateTime.now, ( DateTime.now + 6 ).end_of_day)
when 'custom'
if params[:start_date].blank?
params[:start_date] = DateTime.now.beginning_of_week.strftime('%m/%d/%Y')
end
if params[:end_date].blank?
params[:end_date] = (DateTime.now.end_of_week - 2).strftime('%m/%d/%Y')
end
scope = scope.between_dates(DateTime.strptime(params[:start_date], '%m/%d/%Y'),
DateTime.strptime(params[:end_date], '%m/%d/%Y').end_of_day)
when 'hour'
scope = scope.between_hour_on_day(DateTime.strptime(params[:hour], '%m/%d/%Y %H:
%M'))
when 'today'
scope = scope.between_day(DateTime.now)
end
@events = scope.all
end

74. def index(params)
scope = Event
case params[:timeframe]
when 'tomorrow'
scope = scope.between_day(DateTime.now + 1)
when 'this_week'
scope = scope.between_dates(DateTime.now, ( DateTime.now + 6 ).end_of_day)
when 'custom'
if params[:start_date].blank?
params[:start_date] = DateTime.now.beginning_of_week.strftime('%m/%d/%Y')
end
if params[:end_date].blank?
params[:end_date] = (DateTime.now.end_of_week - 2).strftime('%m/%d/%Y')
end
scope = scope.between_dates(DateTime.strptime(params[:start_date], '%m/%d/%Y'),
DateTime.strptime(params[:end_date], '%m/%d/%Y').end_of_day)
when 'hour'
scope = scope.between_hour_on_day(DateTime.strptime(params[:hour], '%m/%d/%Y %H:
%M'))
when 'today'
scope = scope.between_day(DateTime.now)
end
multiple named scopes
@events = scope.all
end

75. class Event < ActiveRecord::Base
named_scope :between_dates, lambda { |start_date, end_date|
{:conditions => ["at >= ? AND at <= ?", start_date, end_date ] }
}
named_scope :between_hour_on_day, lambda { |start_hour|
end_date = start_hour + 1.hour-1.second
{ :conditions => {:at => start_hour..end_date} }
}
named_scope :between_day, lambda { |date|
start_date = date.at_beginning_of_day
end_date = start_date.end_of_day
{ :conditions => {:at => start_date..end_date} }
}
end

76. different ways
to do the same
class Event < ActiveRecord::Base thing
named_scope :between_dates, lambda { |start_date, end_date|
{:conditions => ["at >= ? AND at <= ?", start_date, end_date ] }
}
named_scope :between_hour_on_day, lambda { |start_hour|
end_date = start_hour + 1.hour-1.second
{ :conditions => {:at => start_hour..end_date} }
}
named_scope :between_day, lambda { |date|
start_date = date.at_beginning_of_day
end_date = start_date.end_of_day
{ :conditions => {:at => start_date..end_date} }
}
end

77. class Event < ActiveRecord::Base
named_scope :between_dates, lambda { |start_date, end_date|
{:conditions => ["at >= ? AND at <= ?", start_date, end_date ] }
}
named_scope :between_hour_on_day, lambda { |start_hour|
end_date = start_hour + 1.hour-1.second
{ :conditions => {:at => start_hour..end_date} }
}
more logic
named_scope :between_day, lambda { |date|
start_date = date.at_beginning_of_day
end_date = start_date.end_of_day
{ :conditions => {:at => start_date..end_date} }
}
end

78. Objectives
Active:
• Isolate unit tests from the database
Passive:
• Deal with bad smells

79. Strategizing
1. Centralize date manipulation logic
2. Unify named scopes
3. Extract logic from Controller
4. Break timeframe into separate pieces

80. def index(params)
case params[:timeframe]
when 'tomorrow'
date = DateTime.now + 1
start_date = date.at_beginning_of_day
end_date = start_date.end_of_day
when 'this_week'
start_date = DateTime.now
end_date = (DateTime.now + 6 ).end_of_day
when 'custom'
start_date = params[:start_date].blank? ? DateTime.now.beginning_of_week :
DateTime.strptime(params[:start_date], '%m/%d/%Y')
end_date = params[:end_date].blank? ? (DateTime.now.end_of_week - 2) :
DateTime.strptime(params[:end_date], '%m/%d/%Y').end_of_day
when 'hour'
start_date = DateTime.strptime(params[:hour], '%m/%d/%Y %H:%M')
end_date = start_date + 1.hour-1.second
when 'today'
date = DateTime.now
start_date = date.at_beginning_of_day
end_date = start_date.end_of_day
end
@events = Event.between_dates(start_date, end_date)
end

81. class Event < ActiveRecord::Base
named_scope :between_dates, lambda { |start_date, end_date|
{:conditions => {:at => start_date..end_date}}
}
end

82. class Event < ActiveRecord::Base
named_scope :between_dates, lambda { |start_date, end_date|
{:conditions => {:at => start_date..end_date}}
}
end
lib/calendar_search_controller.rb | 27 +++++++++++++--------------
lib/event.rb | 13 +------------
spec/event_spec.rb | 37 -------------------------------------
3 files changed, 14 insertions(+), 63 deletions(-)

83. Before
.
............
ds
0 .49367 secon
Finished in res
13 examp les, 0 failu
class Event < ActiveRecord::Base
named_scope :between_dates, lambda { |start_date, end_date|
{:conditions => {:at => start_date..end_date}}
}
end
lib/calendar_search_controller.rb | 27 +++++++++++++--------------
lib/event.rb | 13 +------------
spec/event_spec.rb | 37 -------------------------------------
3 files changed, 14 insertions(+), 63 deletions(-)

84. Before .......
After
.
............
ds Finished in
0 .49367 secon 0.25355 seco
Finished in res 7 examples, nds
13 examp les, 0 failu 0 failures
class Event < ActiveRecord::Base
named_scope :between_dates, lambda { |start_date, end_date|
{:conditions => {:at => start_date..end_date}}
}
end
lib/calendar_search_controller.rb | 27 +++++++++++++--------------
lib/event.rb | 13 +------------
spec/event_spec.rb | 37 -------------------------------------
3 files changed, 14 insertions(+), 63 deletions(-)

85. Strategizing
1. Centralize date manipulation logic
2. Unify named scopes
3. Extract logic from Controller
4. Break timeframe into separate pieces

86. class CalendarSearchController
attr_reader :events
def index(params)
timeframe = TimeFrame.for(params[:timeframe], params[:start_date],
params[:end_date], params[:hour])
@events = Event.between_dates(timeframe.start_date, timeframe.end_date)
end
end
change to tests:
it "should create time frame from params and retrieve events" do
timeframe = TimeFrame.new(DateTime.now, DateTime.now)
TimeFrame.should_receive(:for).with('today', 'start', 'end',
'hour').and_return(timeframe)
events = [Event.new, Event.new]
Event.should_receive(:between_dates).with(timeframe.start_date,
timeframe.end_date).and_return(events)
@controller.index(:timeframe => 'today', :start_date => 'start', :end_date =>
'end', :hour => 'hour')
@controller.events.should == events
end

87. describe "Acceptance tests" do
around(:each) do |example|
Event.transaction { example.run; raise ActiveRecord::Rollback }
end
before do
@controller = CalendarSearchController.new
@today = DateTime.strptime('06/01/2011', '%m/%d/%Y')
DateTime.stub!(:now).and_return(@today)
end
it "should return today's events" do
today_events = [Event.create(:at => @today), Event.create(:at => @today)]
tomorrow = @today + 1
tomorrow_events = [Event.create(:at => tomorrow), Event.create(:at => tomorrow)]
@controller.index(:timeframe => 'today')
@controller.events.should == today_events
end
it "should return tomorrow's events" ...
it "should return this week's events" ...
it "should return events for specified date range" ...
it "should default date range to this business week" ...
it "returns events for a specified hour" ...
end

88. describe "Acceptance tests" do
around(:each) do |example| After
......
Event.transaction { example.run; raise ActiveRecord::Rollback }
end
Finished in
0.24538 seco
before do 6 examples, nds
0 failures
@controller = CalendarSearchController.new
@today = DateTime.strptime('06/01/2011', '%m/%d/%Y')
DateTime.stub!(:now).and_return(@today)
end
it "should return today's events" do
today_events = [Event.create(:at => @today), Event.create(:at => @today)]
tomorrow = @today + 1
tomorrow_events = [Event.create(:at => tomorrow), Event.create(:at => tomorrow)]
@controller.index(:timeframe => 'today')
@controller.events.should == today_events
end
it "should return tomorrow's events" ...
it "should return this week's events" ...
it "should return events for specified date range" ...
it "should default date range to this business week" ...
it "returns events for a specified hour" ...
end

89. class TimeFrame < Struct.new(:start_date, :end_date)
def self.for(type, start_date, end_date, hour)
case type
when 'tomorrow'
date = DateTime.now + 1
TimeFrame.new(date.at_beginning_of_day, date.end_of_day)
when 'this_week'
TimeFrame.new(DateTime.now, (DateTime.now + 6 ).end_of_day)
when 'custom'
start_date = start_date.blank? ? DateTime.now.beginning_of_week :
DateTime.strptime(start_date, '%m/%d/%Y')
end_date = end_date.blank? ? (DateTime.now.end_of_week - 2) :
DateTime.strptime(end_date, '%m/%d/%Y').end_of_day
TimeFrame.new(start_date, end_date)
when 'hour'
start_date = DateTime.strptime(hour, '%m/%d/%Y %H:%M')
end_date = start_date + 1.hour-1.second
TimeFrame.new(start_date, end_date)
when 'today'
date = DateTime.now
TimeFrame.new(date.at_beginning_of_day, date.end_of_day)
end
end
end

90. describe TimeFrame do
before do
@today = DateTime.strptime('06/01/2011', '%m/%d/%Y')
DateTime.stub!(:now).and_return(@today)
end
describe "today's event" do
it "should use beginning and end of day" do
timeframe = TimeFrame.for('today', nil, nil, nil)
timeframe.start_date.should == @today.at_beginning_of_day
timeframe.end_date.should == @today.end_of_day
end
end
...
end

91. describe TimeFrame do
before do
@today = DateTime.strptime('06/01/2011', '%m/%d/%Y')
DateTime.stub!(:now).and_return(@today)
end
describe "today's event" do
it "should use beginning and end of day" do
timeframe = TimeFrame.for('today', nil, nil, nil)
timeframe.start_date.should == @today.at_beginning_of_day
timeframe.end_date.should == @today.end_of_day
end
Rakefile | 4 ++
end
lib/calendar_search_controller.rb | 24 +---------
...
lib/time_frame.rb | 24 ++++++++++
end
spec/acceptance_tests.rb | 75 +++++++++++++++++++++++++++++++
spec/calendar_search_controller_spec.rb | 75 ++++---------------------------
spec/time_frame_spec.rb | 63 ++++++++++++++++++++++++++
6 files changed, 178 insertions(+), 87 deletions(-)

92. Before
.......
ds
describe d in 0 .25355 secon
Finishe TimeFrame do es
before les, 0 failur
7 examp do
@today = DateTime.strptime('06/01/2011', '%m/%d/%Y')
DateTime.stub!(:now).and_return(@today)
end
describe "today's event" do
it "should use beginning and end of day" do
timeframe = TimeFrame.for('today', nil, nil, nil)
timeframe.start_date.should == @today.at_beginning_of_day
timeframe.end_date.should == @today.end_of_day
end
Rakefile | 4 ++
end
lib/calendar_search_controller.rb | 24 +---------
...
lib/time_frame.rb | 24 ++++++++++
end
spec/acceptance_tests.rb | 75 +++++++++++++++++++++++++++++++
spec/calendar_search_controller_spec.rb | 75 ++++---------------------------
spec/time_frame_spec.rb | 63 ++++++++++++++++++++++++++
6 files changed, 178 insertions(+), 87 deletions(-)

93. Before ........
After
.......
ds Finished in
describe d in 0 .25355 secon
she TimeFrame do
0.17938 seco
nds
Fini 8 examples,
before les, 0 failures
7 ex amp do
0 failures
@today = DateTime.strptime('06/01/2011', '%m/%d/%Y')
DateTime.stub!(:now).and_return(@today)
end
describe "today's event" do
it "should use beginning and end of day" do
timeframe = TimeFrame.for('today', nil, nil, nil)
timeframe.start_date.should == @today.at_beginning_of_day
timeframe.end_date.should == @today.end_of_day
end
Rakefile | 4 ++
end
lib/calendar_search_controller.rb | 24 +---------
...
lib/time_frame.rb | 24 ++++++++++
end
spec/acceptance_tests.rb | 75 +++++++++++++++++++++++++++++++
spec/calendar_search_controller_spec.rb | 75 ++++---------------------------
spec/time_frame_spec.rb | 63 ++++++++++++++++++++++++++
6 files changed, 178 insertions(+), 87 deletions(-)

94. Strategizing
1. Centralize date manipulation logic
2. Unify named scopes
3. Extract logic from Controller
4. Break timeframe into separate pieces

95. class TimeFrame
attr_reader :start_date, :end_date
class Today < TimeFrame
def initialize
date = DateTime.now
@start_date, @end_date = date.at_beginning_of_day, date.end_of_day
end
end
...
end
describe TimeFrame::Today do
it "should use beginning and end of day" do
timeframe = TimeFrame::Today.new
timeframe.start_date.should == @today.at_beginning_of_day
timeframe.end_date.should == @today.end_of_day
end
...
end

96. class TimeFrame
...
def self.for(type, start_date, end_date, hour)
case type
when 'tomorrow' then Tomorrow.new
when 'this_week' then ThisWeek.new
when 'custom' then Custom.new(start_date, end_date)
when 'hour' then Hour.new(hour)
when 'today' then Today.new
end
end
end
describe TimeFrame::Today do
...
describe "parsing" do
it "should parse today's timeframe" do
TimeFrame.for('today', nil, nil, nil).should
be_an_instance_of(TimeFrame::Today)
end
...
end
end

97. class TimeFrame
... Before
.def .self.for(type, start_date, end_date, hour)
... ...
case type
ds
0 .17938 secon
when 'tomorrow' then Tomorrow.new
Finished in
when les, 0 failures ThisWeek.new
8 examp 'this_week' then
when 'custom' then Custom.new(start_date, end_date)
when 'hour' then Hour.new(hour)
when 'today' then Today.new
end
end
end
describe TimeFrame::Today do
...
describe "parsing" do
it "should parse today's timeframe" do
TimeFrame.for('today', nil, nil, nil).should
be_an_instance_of(TimeFrame::Today)
end
...
end
end

98. class TimeFrame
... Before ............
After
def .self.for(type, start_date, end_date, hour) .
.... ...
case type
ds Finished in
when d in 0 .17938 secon
she 'tomorrow' then Tomorrow.new
0.19023 seco
nds
Fini 13 examples,
when les, 0 failures ThisWeek.new
8 examp 'this_week' then
0 failures
when 'custom' then Custom.new(start_date, end_date)
when 'hour' then Hour.new(hour)
when 'today' then Today.new
end
end
end
describe TimeFrame::Today do
...
describe "parsing" do
it "should parse today's timeframe" do
TimeFrame.for('today', nil, nil, nil).should
be_an_instance_of(TimeFrame::Today)
end
...
end
end

99. class TimeFrame
... Before ............
After
def .self.for(type, start_date, end_date, hour) .
.... ...
case type
ds Finished in
when d in 0 .17938 secon
she 'tomorrow' then Tomorrow.new
0.19023 seco
nds
Fini 13 examples,
when les, 0 failures ThisWeek.new
8 examp 'this_week' then
0 failures
when 'custom' then Custom.new(start_date, end_date)
when 'hour' then Hour.new(hour)
when 'today' then Today.new
end
end
end
describe TimeFrame::Today do
...
describe "parsing" do
lib/time_frame.rb | 59 +++++++++++++++++++++++++++++++++-------------
it "should parse today's timeframe" do
spec/time_frame_spec.rb | 44 ++++++++++++++++++++++++++--------
TimeFrame.for('today', nil, nil, nil).should
2 files changed, 75 insertions(+), 28 deletions(-)
be_an_instance_of(TimeFrame::Today)
end
...
end
end

100. “Big Picture”
• Architectural Changes
• Consolidating different approaches
• Substituting components/frameworks

101. “Big Picture”

102. “Big Picture”
Scope Risk Effort Communication

103. Change

104. x x x x
x x x
Change
x xx
x

105. x x x x
x x x
Change
x xx
x

106. x
x
x x x x
x x x
xx
x Change
xxx
x xx
x

107. x x
xx x
x x
x x x x
x x x
xx
x Change
xxx
x xx
x

108. x x
xx x
x x
x x x x
x x x
xx
x Change
xxx
x xx
x
xx
xx x x
xxx xx
x

109. x x
x x x
x x x xx x
x x x x
x
x x x x
x x x
xx x
x Change
xxx
x x
x xx x
x
x x xx
xx x x x x
x
xxx xx
x
x x x
x

111. Change

112. x x x x
x x x
Change
x xx
x

113. x x x x
x x x
Change
x xx
x

114. x
Prereq
x x x
x x x
Change
x xx
x

115. x
Prereq
x x
x Prereq
x x x
Change
x xx
x

116. x
Prereq
x x
x Prereq
x x x
Change
x xx
Prereq
x

117. Prereq Prereq
Change
Prereq

118. x
x
Prereq Prereq
xx
x Change
xxx
Prereq

119. x
Prereq
x
Prereq Prereq
xx
x Prereq Change
xxx
Prereq

120. Prereq
Prereq Prereq
Prereq Change
Prereq

121. Prereq
Prereq Prereq
Prereq Change
Prereq

122. Prereq
Prereq Prereq
Prereq ✔ Change
Prereq

123. Prereq
Prereq Prereq
Prereq ✔ Change
Prereq

124. Prereq ✔
Prereq Prereq
Prereq ✔ Change
Prereq

125. Prereq ✔
Prereq ✔ Prereq
Prereq ✔ Change
Prereq

126. Prereq ✔
Prereq ✔ Prereq
Prereq ✔ Change
Prereq

127. Prereq ✔
Prereq ✔ Prereq ✔
Prereq ✔ Change
Prereq

128. Prereq ✔
Prereq ✔ Prereq ✔
Prereq ✔ Change
Prereq

129. Prereq ✔
Prereq ✔ Prereq ✔
Prereq ✔ Change
Prereq ✔

130. Prereq ✔
Prereq ✔ Prereq ✔
Prereq ✔ Change ✔
Prereq ✔

131. A story
APP

132. A story
APP
SVC

133. A story
APP
SVC

134. A story
APP
SVC

135. The truth
APP
Model
View
Controller

136. The truth
APP
Model
View
Controller
Helper

137. The truth
APP
Model
View
SVC
Controller
Helper

138. The truth
APP
Model
View
SVC
Controller
everything is
going to break !!!
Helper

139. Transitional
Architecture
APP
Model
View
Controller
SVC
Helper

140. Transitional
Architecture
APP
Model
View
Controller
SVC
Helper

141. Transitional
Architecture
APP
Model
View
Controller
SVC
Helper

142. Transitional
Architecture
APP
Model
View
Controller
SVC
Helper

143. Transitional
Architecture
APP
Model
View
Controller
SVC
Helper

144. Transitional
Architecture
APP
Model
View
Controller
SVC
Helper

145. Transitional
Architecture
• Go:
• “Branch by Abstraction”
• Migrating from iBatis to Hibernate
• Migrating from Velocity/JsTemplate to
JRuby on Rails

146. Transitional
Architecture
• Go:
• “Branch by Abstraction”
• Migrating from iBatis to Hibernate
• Migrating from Velocity/JsTemplate to
JRuby on Rails
-
0 11/05/make-large
http://continuo usdelivery.com/2
-
l y-with-branch-by
scale-cha nges-incremental
abstraction/

147. References
Books:
"Refactoring: Improving the Design of Existing Code" - Martin Fowler, Kent Beck, John
Brant, William Opdyke, Don Roberts
"Refactoring to Patterns" - Joshua Kerievsky
"Working Effectively with Legacy Code" - Michael Feathers
"Beheading the Software Beast: Relentless Restructurings with The Mikado Method" -
Daniel Brolund, Ola Ellnestam
Credits (fotos):
http://www.flickr.com/photos/dhammza/2227347832/
http://www.flickr.com/photos/pragdave/173640462/
Links:
http://paulhammant.com/2011/09/01/refactoring-experiment
http://continuousdelivery.com/2011/05/make-large-scale-changes-incrementally-with-
branch-by-abstraction/
Code:
https://github.com/dtsato/refactoring_experiment
https://github.com/dtsato/kata-refactoring-calendar

148. Obrigado!
Danilo Sato - @dtsato
ThoughtWorks
www.dtsato.com