1. Fluent Refactoring
Sam Livingston-Gray
THERE
WILL BE
CODE!
It may be
this small
(1..100).each do |i|
s = ''
fizz = (i % 3).zero?
buzz = (i % 5).zero?
s << 'Fizz' if fizz
s << 'Buzz' if buzz
s << '!' if fizz || buzz
s = i if s =~ /^$/
puts s
end
1

2. Let’s Talk About Math!
2

3. http://2012books.lardbucket.org/books/elementary-algebra/section_06/5d10b670d78abac93a4572dc0c2afb0f.jpg
3

4. http://www.wikihow.com/Image:Solve-for-X-Step-12.jpg
4

5. http://math.about.com/od/algebra/ss/birthday.htm
5

6. http://www.smosh.com/smosh-pit/photos/16-wonderfully-stupid-test-answers
6

7. Algebra
7

8. Algebra Isn’t Math
8

9. Algebra Isn’t all of Math
9

10. Algebra ⊂ Math
Math
Algebra
10

11. http://upload.wikimedia.org/wikipedia/commons/thumb/0/08/NautilusCutawayLogarithmicSpiral.jpg/793px-NautilusCutawayLogarithmicSpiral.jpg
11

12. http://upload.wikimedia.org/wikipedia/commons/a/a4/Mandelbrot_sequence_new.gif
12

13. http://mathequalslove.blogspot.com/2012/12/hexaflexagon-love.html
13

14. http://think-like-a-git.net/sections/graph-theory/seven-bridges-of-konigsberg.html
14

15. Math is a Language
Algebra is its Grammar
15

16. Dick and Jane
16

17. Fluent Refactoring
17

18. http://www.kickasslabs.com/2012/04/28/rails-conf-2012-images/100_0304/
Can I get a
definition?
18

19. Flu·en·cy (noun)
What you can say when you’re
not thinking about how to say it
19

20. What you can say when you’re
woken up in the middle of the night
with a flashlight in your face
Flu·en·cy (noun)
20

21. http://dailyawesimity.files.wordpress.com/2013/01/cat-stress-relief-4.jpg
Stress
21

22. http://www.jamesshore.com/Blog/Proficiencies-of-Planning.html
Level 1
Tarzan at
a party
“Beer!”
“Good party.”
Level 2
Going to
the party
"Where is the party?"
"How do I get to the party?"
Level 3
Discussing
the party
"What happened at the party
last night?"
Level 4 Charlie Rose "Should parties be illegal?"
Levels of Proficiency
22

23. Re·fac·tor·ing (noun)
"...a disciplined technique for
restructuring an existing body of code,
altering its internal structure without
changing its external behavior."
-refactoring.com
23

24. http://refactoring.com/
"...a disciplined
technique for restructuring an existing
body of code, altering its internal
structure without changing its external
behavior."
24

25. "Yeah, we're going to have to take
a couple of weeks out of the schedule
for refactoring, and that's probably going
to break some stuff."
Doin It Rong
25

26. "Yeah, we're going to have to take
a couple of weeks out of the schedule
for refactoring, and that's probably going
to break some stuff."
Doin It Rong
26

27. "Yeah, we're going to have to take
a couple of weeks out of the schedule
for refactoring, and that's probably going
to break some stuff."
Doin It Rong
27

28. Re·fac·tor·ing (noun)
"...a disciplined technique for
restructuring an existing body of code,
altering its internal structure without
changing its external behavior."
-refactoring.com
28

29. http://refactoring.com/
"...a disciplined technique for
restructuring an existing body of code,
altering its internal structure
without changing its
external behavior."
29

30. Tests are implied.
-Katrina Owen,
“Therapeutic Refactoring”
30

31. Re·fac·tor·ing (noun)
"...a disciplined technique for
restructuring an existing body of
code, altering its internal structure
without changing its external
behavior."
-refactoring.com
31

32. Re·fac·tor·ing (noun)
"...a disciplined technique for
restructuring an existing body of
code, altering its internal structure
without changing its external
behavior."
32

33. Re·fac·tor·ing (noun)
A technique for
restructuring code
without changing behavior
33

34. Re·fac·tor (verb)
To restructure code
without changing behavior
34

35. Tell a clearer story
with fewer details
35

36. Re·fac·tor·ing (noun)
A language that describes
ways to make your code
suck less.
36

37. THESISES
37

38. THESISES
THESES
38

39. THESISES
THESES
THESII
39

40. THESISES
THESES
THESII
MY POINT(S)
40

41. You're probably already fluent
in refactoring.
Level 1:
RenameVariable; Rename Method.
41

42. You can become more fluent in
refactoring.
It just takes practice.
42

43. Putting in the practice to
become more fluent in
refactoring is worth it.
Because you’ll be able to say more
things when you’re under stress.
43

44. Refactoring Session
44

45. Used with:
• Permission
• Obfuscation
• Respect
Production Rails Code
45

46. Schedule Cable Installs
46

47. class InstallationsController < ActionController::Base
# lots more stuff...
def schedule
desired_date = params[:desired_date]
if request.xhr?
begin
if @installation.pending_credit_check?
render :json => {:errors => ["Cannot schedule installation while credit check is pending"]}, :status => 400
return
end
audit_trail_for(current_user) do
if @installation.schedule!(desired_date, :installation_type => params[:installation_type], :city => @city)
if @installation.scheduled_date
date = @installation.scheduled_date.in_time_zone(@installation.city.timezone).to_date
render :json => {:errors => nil, :html => schedule_response(@installation, date)}
end
else
render :json => {:errors => [%Q{Could not update installation. #{@installation.errors.full_messages.join(' ')}}] }
end
end
rescue ActiveRecord::RecordInvalid => e
render :json => {:errors => [e.message] }
rescue ArgumentError => e
render :json => {:errors => ["Could not schedule installation. Start by making sure the desired date is on a business day."]}
end
else
if @installation.pending_credit_check?
flash[:error] = "Cannot schedule installation while credit check is pending"
redirect_to installations_path(:city_id => @installation.city_id, :view => "calendar") and return
end
begin
audit_trail_for(current_user) do
if @installation.schedule!(desired_date, :installation_type => params[:installation_type], :city => @city)
if @installation.scheduled_date
if @installation.customer_provided_equipment?
flash[:success] = %Q{Installation scheduled}
else
flash[:success] = %Q{Installation scheduled! Don't forget to order the equipment also.}
end
end
else
flash[:error] = %Q{Could not schedule installation, check the phase of the moon}
end
end
rescue => e
flash[:error] = e.message
end
redirect_to(@installation.customer_provided_equipment? ? customer_provided_installations_path
: installations_path(:city_id => @installation.city_id, :view => "calendar"))
end
end
# lots more stuff...
end
47

48. class InstallationsController < ActionController::Base
# lots more stuff...
def schedule
desired_date = params[:desired_date]
if request.xhr?
begin
if @installation.pending_credit_check?
render :json => {:errors => ["Cannot schedule installation while credit check is pending"]}, :status => 400
return
end
audit_trail_for(current_user) do
if @installation.schedule!(desired_date, :installation_type => params[:installation_type], :city => @city)
if @installation.scheduled_date
date = @installation.scheduled_date.in_time_zone(@installation.city.timezone).to_date
render :json => {:errors => nil, :html => schedule_response(@installation, date)}
end
else
render :json => {:errors => [%Q{Could not update installation. #{@installation.errors.full_messages.join(' ')}}] }
end
end
rescue ActiveRecord::RecordInvalid => e
render :json => {:errors => [e.message] }
rescue ArgumentError => e
render :json => {:errors => ["Could not schedule installation. Start by making sure the desired date is on a business day."]}
end
else
if @installation.pending_credit_check?
flash[:error] = "Cannot schedule installation while credit check is pending"
redirect_to installations_path(:city_id => @installation.city_id, :view => "calendar") and return
end
begin
audit_trail_for(current_user) do
if @installation.schedule!(desired_date, :installation_type => params[:installation_type], :city => @city)
if @installation.scheduled_date
if @installation.customer_provided_equipment?
flash[:success] = %Q{Installation scheduled}
else
flash[:success] = %Q{Installation scheduled! Don't forget to order the equipment also.}
end
end
else
flash[:error] = %Q{Could not schedule installation, check the phase of the moon}
end
end
rescue => e
flash[:error] = e.message
end
redirect_to(@installation.customer_provided_equipment? ? customer_provided_installations_path
: installations_path(:city_id => @installation.city_id, :view => "calendar"))
end
end
# lots more stuff...
end
Observations
~800 lines in file
~50 lines in method
Longest line: 177 chars
Indentation: 4-16 spaces
Nested control
structures:
audit_trail_for
begin/rescue/end
if/else/end
48

49. http://scientopia.org/blogs/whitecoatunderground/2009/06/10/my-head-just-asploded-twice/
Complexity
49

50. http://shipitsquirrel.github.io/
Ship it!
50

51. http://shipitsquirrel.github.io/
Ship Shit!
51

52. http://hyperboleandahalf.blogspot.com/2010/06/this-is-why-ill-never-be-adult.html
~800 lines
52

53. http://hyperboleandahalf.blogspot.com/2010/06/this-is-why-ill-never-be-adult.html
~800 lines
53

54. Make the Job Smaller
54

55. Replace Method with
Method Object
55

56. class InstallationsController <
ActionController::Base
def schedule
# LOTS OF CODE
end
end
56

57. class InstallationsController <
ActionController::Base
def schedule
end
end
class ScheduleInstallation
def call
end
end
# LOTS OF CODE
57

58. class InstallationsController <
ActionController::Base
def schedule
end
end
class ScheduleInstallation
def call
end
end
# LOTS OF CODE
58

59. class InstallationsController <
ActionController::Base
def schedule
end
end
class ScheduleInstallation
def call
end
end
ScheduleInstallation.new.call
# LOTS OF CODE
59

60. class ScheduleInstallation
def call
# LOTS OF CODE
end
end
60

61. class ScheduleInstallation
def initialize(controller)
@controller = controller
end
def call
# LOTS OF CODE
end
end
61

62. class ScheduleInstallation
def initialize(controller)
@controller = controller
end
def call
# LOTS OF CODE
end
def method_missing(m, *a, &b)
@controller.send(m, *a, &b)
end
end
62

63. Code Archaeology
63

64. if request.xhr?
# ...20 lines...
else
# ...22 lines...
end
64

65. if request.xml_http_request?
# ...20 lines...
else
# ...22 lines...
end
65

66. if request.xml_http_request?
begin
if @installation.pending_credit_check?
render :json => #...
return
end
#...
end
else
# ...22 lines...
end
66

67. if request.xhr?
begin
if @installation.pending_credit_check?
render :json => #...
return
end
#...
end
else
if @installation.pending_credit_check?
flash[:error] = #...
redirect_to installations_path(:city_id =>
end
begin
#...
end
67

68. ion.pending_credit_check?
n => #...
n.pending_credit_check?
= #...
nstallations_path(:city_id => @installation.city
68

69. check?
eck?
city_id => @installation.city_id, :view => "cale
69

70. lation.city_id, :view => "calendar") and return
70

71. if request.xhr?
begin
if @installation.pending_credit_check?
render :json => #...
return
end
#...
end
else
if @installation.pending_credit_check?
flash[:error] = #...
redirect_to installations_path(:city_id =>
return
end
begin
#...
end
if request.xhr?
if @installation.pend
render :json => #..
return
end
else
if @installation.pend
flash[:error] = #..
redirect_to(...) an
return
end
end
if request.xhr?
#...
else
#...71

72. if request.xhr?
#...
else
#...
end
if request.xhr?
#...
else
#...
end
ZOMG
duplication!!!1!!
72

73. if request.xhr?
if @installation.pending_credit_check?
#...
end
else
if @installation.pending_credit_check?
#...
end
end
if request.xhr?
#...
else
#...
end
73

74. Emphasis
74

75. if request.xhr?
if @installation.pending_credit_check?
#...
end
else
if @installation.pending_credit_check?
#...
end
end
75

76. Flatten Nested
Conditionals
source: Michael Feathers,
writing for Dr. Dobbs
76

77. if request.xhr?
if @installation.pending_credit_check?
render :json => #...
return
end
else
if @installation.pending_credit_check?
flash[:error] = #...
redirect_to #...
return
end
end
77

78. if ajax
if pending_credit_check
render :json => #...
return
end
else
if pending_credit_check
flash[:error] = #...
redirect_to #...
return
end
end
78

79. if ajax
if pending_credit_check
render :json => #...
return
end
else
if pending_credit_check
flash[:error] = #...
redirect_to #...
return
end
end
if ajax
if pending_credit_che
render :json => #..
return
end
end
if not ajax
if pending_credit_che
flash[:error] = #..
redirect_to #...
return
end
end
79

80. if ajax
if pending_credit_check
render :json => #...
return
end
end
if not ajax
if pending_credit_check
flash[:error] = #...
redirect_to #...
return
end
end
if ajax && pending_cred
render :json => #...
return
end
if (not ajax) && pendin
flash[:error] = #...
redirect_to #...
return
end
80

81. if ajax && pending_credit_check
render :json => #...
return
end
if (not ajax) && pending_credit_check
flash[:error] = #...
redirect_to #...
return
end
if pending_credit_check
if ajax
render :json => #..
return
end
if not ajax
flash[:error] = #..
redirect_to #...
return
end
end
81

82. if pending_credit_check
if ajax
render :json => #...
return
end
if not ajax
flash[:error] = #...
redirect_to #...
return
end
end
if pending_credit_check
if ajax
render :json => #..
return
else
flash[:error] = #..
redirect_to #...
return
end
end
82

83. if pending_credit_check
if ajax
render :json => #...
return
else
flash[:error] = #...
redirect_to #...
return
end
end
if pending_credit_check
if ajax
render :json => #..
else
flash[:error] = #..
redirect_to #...
end
return
end
83

84. if ajax
if pending_credit_check
render :json => #...
return
end
else
if pending_credit_check
flash[:error] = #...
redirect_to #...
return
end
end
if pending_credit_check
if ajax
render :json => #..
else
flash[:error] = #..
redirect_to #...
end
return
end
84

85. if pending_credit_check
if ajax
render :json => #...
else
flash[:error] = #...
redirect_to #...
end
return
end
if pending_credit_check
cant_schedule_while_c
return
end
85

86. Exception Handling
86

87. raise “wtf” if coin.toss.heads?begin
raise “wtf” if coin.t
end
87

88. begin
raise “wtf” if coin.toss.heads?
end
begin
raise “wtf” if coin.t
rescue => e
raise e
end
88

89. begin
raise “wtf” if coin.toss.heads?
rescue => e
raise e
end
89

90. begin
begin
raise “wtf” if coin.toss.heads?
rescue
#...
end
rescue => e
raise e
end
90

91. begin
begin
raise “wtf” if coin.toss.heads?
rescue
if request.xhr?
raise “tfw” if tuesday?
else
raise “yak” if Moon.gibbous?
end
end
rescue => e
raise e
end
begin
begin
raise “wtf” if coin
rescue
if request.xhr?
raise “tfw” if tu
else
raise “yak” if Mo
end
end
rescue => e
if request.xhr?
raise e
else
raise e
end
end91

92. begin
begin
raise “wtf” if coin.toss.heads?
rescue
if request.xhr?
raise “tfw” if tuesday?
else
raise “yak” if Moon.gibbous?
end
end
rescue => e
if request.xhr?
raise e
else
raise e
end
end
begin
begin
raise “wtf” if coin
rescue
if request.xhr?
# DO NOTHING
else
raise “yak” if Mo
end
end
rescue => e
if request.xhr?
raise “tfw” if tues
else
raise e
end
end92

93. begin
begin
raise “wtf” if coin.toss.heads?
rescue
if request.xhr?
# DO NOTHING
else
raise “yak” if Moon.gibbous?
end
end
rescue => e
if request.xhr?
raise “tfw” if tuesday?
else
raise e
end
end
begin
begin
raise “wtf” if coin
rescue
if request.xhr?
# DO NOTHING
else
# DO NOTHING
end
end
rescue => e
if request.xhr?
raise “tfw” if tues
else
raise “yak” if Moon
end
end93

94. begin
begin
raise “wtf” if coin.toss.heads?
rescue
if request.xhr?
# DO NOTHING
else
# DO NOTHING
end
end
rescue => e
if request.xhr?
raise “tfw” if tuesday?
else
raise “yak” if Moon.gibbous?
end
end
begin
begin
raise “wtf” if coin
rescue
# DO NOTHING
end
rescue => e
if request.xhr?
raise “tfw” if tues
else
raise “yak” if Moon
end
end
94

95. begin
begin
raise “wtf” if coin.toss.heads?
rescue
# DO NOTHING
end
rescue => e
if request.xhr?
raise “tfw” if tuesday?
else
raise “yak” if Moon.gibbous?
end
end
begin
begin
raise “wtf” if coin
end
rescue => e
if request.xhr?
raise “tfw” if tues
else
raise “yak” if Moon
end
end
95

96. begin
begin
raise “wtf” if coin.toss.heads?
end
rescue => e
if request.xhr?
raise “tfw” if tuesday?
else
raise “yak” if Moon.gibbous?
end
end
begin
raise “wtf” if coin.t
rescue => e
if request.xhr?
raise “tfw” if tues
else
raise “yak” if Moon
end
end
96

97. begin
raise “wtf” if coin.toss.heads?
rescue => e
if request.xhr?
raise “tfw” if tuesday?
else
raise “yak” if Moon.gibbous?
end
end
begin
raise “wtf” if coin.t
rescue => e
handle_exception(e)
end
97

98. Training Montage
98

99. class ScheduleInstallation
def call
desired_date = params[:desired_date]
if @installation.pending_credit_check?
cant_schedule_while_credit_check_pending
return
end
begin
if request.xhr?
audit_trail_for(current_user) do
if @installation.schedule!(desired_date, :installation_type => params[:installation_type], :city => @city)
if @installation.scheduled_date
date = @installation.scheduled_date.in_time_zone(@installation.city.timezone).to_date
render :json => {:errors => nil, :html => schedule_response(@installation, date)}
end
else
render :json => {:errors => [%Q{Could not update installation. #{@installation.errors.full_messages.join(' ')}}] }
end
end
else
audit_trail_for(current_user) do
if @installation.schedule!(desired_date, :installation_type => params[:installation_type], :city => @city)
if @installation.scheduled_date
if @installation.customer_provided_equipment?
flash[:success] = %Q{Installation scheduled}
else
flash[:success] = %Q{Installation scheduled! Don't forget to order the equipment also.}
end
end
else
flash[:error] = %Q{Could not schedule installation, check the phase of the moon}
end
end
redirect_to(@installation.customer_provided_equipment? ? customer_provided_installations_path : installations_path(:city_id =>
@installation.city_id, :view => "calendar"))
end
rescue Exception => e
handle_exception e
end
end
end
99

100. class ScheduleInstallation
def call
desired_date = params[:desired_date]
if @installation.pending_credit_check?
cant_schedule_while_credit_check_pending
return
end
begin
audit_trail_for(current_user) do
if request.xhr?
if @installation.schedule!(desired_date, :installation_type => params[:installation_type], :city => @city)
if @installation.scheduled_date
date = @installation.scheduled_date.in_time_zone(@installation.city.timezone).to_date
render :json => {:errors => nil, :html => schedule_response(@installation, date)}
end
else
render :json => {:errors => [%Q{Could not update installation. #{@installation.errors.full_messages.join(' ')}}] }
end
else
if @installation.schedule!(desired_date, :installation_type => params[:installation_type], :city => @city)
if @installation.scheduled_date
if @installation.customer_provided_equipment?
flash[:success] = %Q{Installation scheduled}
else
flash[:success] = %Q{Installation scheduled! Don't forget to order the equipment also.}
end
end
else
flash[:error] = %Q{Could not schedule installation, check the phase of the moon}
end
redirect_to(@installation.customer_provided_equipment? ? customer_provided_installations_path : installations_path(:city_id =>
@installation.city_id, :view => "calendar"))
end
end
rescue Exception => e
handle_exception e
end
end
end
100

101. class ScheduleInstallation
def call
if @installation.pending_credit_check?
cant_schedule_while_credit_check_pending
return
end
begin
audit_trail_for(current_user) do
if request.xhr?
if @installation.schedule!(params[:desired_date], :installation_type => params[:installation_type], :city => @city)
if @installation.scheduled_date
date = @installation.scheduled_date.in_time_zone(@installation.city.timezone).to_date
render :json => {:errors => nil, :html => schedule_response(@installation, date)}
end
else
render :json => {:errors => [%Q{Could not update installation. #{@installation.errors.full_messages.join(' ')}}] }
end
else
if @installation.schedule!(params[:desired_date], :installation_type => params[:installation_type], :city => @city)
if @installation.scheduled_date
if @installation.customer_provided_equipment?
flash[:success] = %Q{Installation scheduled}
else
flash[:success] = %Q{Installation scheduled! Don't forget to order the equipment also.}
end
end
else
flash[:error] = %Q{Could not schedule installation, check the phase of the moon}
end
redirect_to(@installation.customer_provided_equipment? ? customer_provided_installations_path : installations_path(:city_id =>
@installation.city_id, :view => "calendar"))
end
end
rescue Exception => e
handle_exception e
end
end
end
101

102. class ScheduleInstallation
def call
if @installation.pending_credit_check?
cant_schedule_while_credit_check_pending
return
end
begin
audit_trail_for(current_user) do
success = schedule!
if request.xhr?
if success
if @installation.scheduled_date
date = @installation.scheduled_date.in_time_zone(@installation.city.timezone).to_date
render :json => {:errors => nil, :html => schedule_response(@installation, date)}
end
else
render :json => {:errors => [%Q{Could not update installation. #{@installation.errors.full_messages.join(' ')}}] }
end
else
if success
if @installation.scheduled_date
if @installation.customer_provided_equipment?
flash[:success] = %Q{Installation scheduled}
else
flash[:success] = %Q{Installation scheduled! Don't forget to order the equipment also.}
end
end
else
flash[:error] = %Q{Could not schedule installation, check the phase of the moon}
end
redirect_to(@installation.customer_provided_equipment? ? customer_provided_installations_path : installations_path(:city_id =>
@installation.city_id, :view => "calendar"))
end
end
rescue Exception => e
handle_exception e
end
end
end
102

103. class ScheduleInstallation
def call
if @installation.pending_credit_check?
cant_schedule_while_credit_check_pending
return
end
begin
audit_trail_for(current_user) do
success = schedule!
if success
if request.xhr?
if @installation.scheduled_date
date = @installation.scheduled_date.in_time_zone(@installation.city.timezone).to_date
render :json => {:errors => nil, :html => schedule_response(@installation, date)}
end
else
if @installation.scheduled_date
if @installation.customer_provided_equipment?
flash[:success] = %Q{Installation scheduled}
else
flash[:success] = %Q{Installation scheduled! Don't forget to order the equipment also.}
end
end
redirect_to(@installation.customer_provided_equipment? ? customer_provided_installations_path : installations_path(:city_id
=> @installation.city_id, :view => "calendar"))
end
else
if request.xhr?
render :json => {:errors => [%Q{Could not update installation. #{@installation.errors.full_messages.join(' ')}}] }
else
flash[:error] = %Q{Could not schedule installation, check the phase of the moon}
redirect_to(@installation.customer_provided_equipment? ? customer_provided_installations_path : installations_path(:city_id
=> @installation.city_id, :view => "calendar"))
end
end
end
rescue Exception => e
handle_exception e
end
end
end
103

104. class ScheduleInstallation
def call
if @installation.pending_credit_check?
cant_schedule_while_credit_check_pending
return
end
begin
audit_trail_for(current_user) do
success = schedule!
if success
if request.xhr?
if @installation.scheduled_date
date = @installation.scheduled_date.in_time_zone(@installation.city.timezone).to_date
render :json => {:errors => nil, :html => schedule_response(@installation, date)}
end
else
if @installation.scheduled_date
if @installation.customer_provided_equipment?
flash[:success] = %Q{Installation scheduled}
else
flash[:success] = %Q{Installation scheduled! Don't forget to order the equipment also.}
end
end
redirect_to(@installation.customer_provided_equipment? ? customer_provided_installations_path : installations_path(:city_id
=> @installation.city_id, :view => "calendar"))
end
else
scheduling_failed
end
end
rescue Exception => e
handle_exception e
end
end
end
104

105. class ScheduleInstallation
def call
if @installation.pending_credit_check?
cant_schedule_while_credit_check_pending
return
end
begin
audit_trail_for(current_user) do
success = schedule!
if success
if @installation.scheduled_date
if request.xhr?
date = @installation.scheduled_date.in_time_zone(@installation.city.timezone).to_date
render :json => {:errors => nil, :html => schedule_response(@installation, date)}
else
if @installation.customer_provided_equipment?
flash[:success] = %Q{Installation scheduled}
else
flash[:success] = %Q{Installation scheduled! Don't forget to order the equipment also.}
end
end
end
if request.xhr?
# do nothing
else
redirect_to(@installation.customer_provided_equipment? ? customer_provided_installations_path : installations_path(:city_id
=> @installation.city_id, :view => "calendar"))
end
else
scheduling_failed
end
end
rescue Exception => e
handle_exception e
end
end
end
105

106. class ScheduleInstallation
def call
if @installation.pending_credit_check?
cant_schedule_while_credit_check_pending
return
end
begin
audit_trail_for(current_user) do
success = schedule!
if success
if @installation.scheduled_date
scheduling_succeeded
end
if request.xhr?
# do nothing
else
redirect_to(@installation.customer_provided_equipment? ? customer_provided_installations_path : installations_path(:city_id
=> @installation.city_id, :view => "calendar"))
end
else
scheduling_failed
end
end
rescue Exception => e
handle_exception e
end
end
end
106

107. class ScheduleInstallation
def call
if @installation.pending_credit_check?
cant_schedule_while_credit_check_pending
return
end
begin
audit_trail_for(current_user) do
success = schedule!
if success
if @installation.scheduled_date
scheduling_succeeded
end
do_post_success_cleanup
else
scheduling_failed
end
end
rescue Exception => e
handle_exception e
end
end
end
107

108. class ScheduleInstallation
def call
if @installation.pending_credit_check?
cant_schedule_while_credit_check_pending
return
end
begin
audit_trail_for(current_user) do
if schedule!
if @installation.scheduled_date
scheduling_succeeded
end
do_post_success_cleanup
else
scheduling_failed
end
end
rescue Exception => e
handle_exception e
end
end
end
108

109. class ScheduleInstallation
def call
if @installation.pending_credit_check?
cant_schedule_while_credit_check_pending
return
end
begin
audit_trail_for(current_user) do
if schedule!
if @installation.scheduled_date
scheduling_succeeded
end
do_post_success_cleanup
else
scheduling_failed
end
end
rescue Exception => e
handle_exception e
end
end
end
request.xhr?
109

110. Under The Rug
110

111. class ScheduleInstallation
def cannot_schedule_while_#...
if request.xhr?
# ...1 line...
else
# ...2 lines...
end
end
def handle_exception(e)
if request.xhr?
# ...7 lines...
else
# ...2 lines...
end
end
def scheduling_failed
if request.xhr?
# ...1 line...
else
# ...2 lines...
end
end
def scheduling_succeeded
if request.xhr?
# ...2 lines...
else
# ...5 lines...
end
end
def do_post_success_cleanup
if request.xhr?
# DO NOTHING
else
# ...1 line...
end
end
end
111

112. class ScheduleInstallation
private
def scheduling_failed
if request.xhr?
render :json => {:errors => [#...
else
flash[:error] = #...
redirect_to #...
end
end
end
112

113. Single Responsibility
Principle
113

114. ScheduleInstallation
ScheduleInstallationAnd
DoOneThingForAJAXRequestsAnd
DoSomethingElseForHTMLRequests
114

115. ScheduleInstallation
ScheduleInstallation And
DoOneThingForAJAXRequests And
DoSomethingElseForHTMLRequests
115

116. “Methods, like classes,
should have a single
responsibility.”
-Sandi Metz
116

117. http://en.wikipedia.org/wiki/File:Bill_%26_Ted%27s_Excellent_Adventure_(Original_Motion_Picture_Soundtrack).jpg
117

118. http://en.wikipedia.org/wiki/File:Paris_Tuileries_Garden_Facepalm_statue.jpg
118

119. Single Responsibility
Principle
Every class should have a single
responsibility, and that responsibility
should be entirely encapsulated
by the class.
119

120. ScheduleInstallation
ScheduleInstallation And
DoOneThingForAJAXRequests And
DoSomethingElseForHTMLRequests
120

121. Responder
121

122. 122
InstallationsController

123. 123
InstallationsController
ScheduleInstallation
???

124. 124
InstallationsController
Responder
???
ScheduleInstallation
???

125. class ScheduleInstallation
def call
private
def cannot_schedule_while_credit_check_pendin
def handle_exception(e)
def scheduling_failed
def scheduling_succeeded
def do_post_success_cleanup
end
class Responder
end
class ScheduleInstallat
def call
end
class Responder
def cannot_schedule_w
def handle_exception(
def scheduling_failed
def scheduling_succee
def do_post_success_c
end
125

126. 126
Dualism

127. class Responder
def cannot_schedule_while_credit_check_pending
# ...6 lines...
end
def cannot_schedule_while_credit_check_pending
if request.xhr?
# ...1 line...
else
# ...2 lines...
end
end
def handle_exception(e)
if request.xhr?
# ...7 lines...
else
# ...2 lines...
end
end
def scheduling_failed
if request.xhr?
# ...1 line...
else
# ...2 lines...
end
end
def scheduling_succeeded
if request.xhr?
# ...2 lines...
else
# ...5 lines...
end
end
def do_post_success_cleanup
if request.xhr?
# NOP
else
# ...2 lines...
end
end
end

128. if request.xhr?
# do foo
else
# do bar
end

129. Replace Conditional
With Polymorphism
129

130. class Responder
def cannot_schedule_while_credit_check_pending
def handle_exception(e)
def scheduling_failed
def scheduling_succeeded
def do_post_success_cleanup
end
class AJAXResponder
def
cannot_schedule_while_cre
def handle_exception(e)
def scheduling_failed
def scheduling_succeede
def do_post_success_cle
end
class HTMLResponder
def
cannot_schedule_while_cre
def handle_exception(e)
def scheduling_failed
def scheduling_succeede
def do_post_success_cle
end

131. class AJAXResponder
def scheduling_failed
if request.xhr?
render :json => #...
else
flash[:error] = #...
redirect_to #...
end
end
end
class HTMLResponder
def scheduling_failed
if request.xhr?
render :json => #...
else
flash[:error] = #...
redirect_to #...
end
end
end
class AJAXResponder
def scheduling_failed
render :json => #...
end
end
class HTMLResponder
def scheduling_failed
flash[:error] = #...
redirect_to #...
end
end

132. 132
InstallationsController
Responder
???
ScheduleInstallation
???

133. class InstallationsController
< ActionController::Base
def schedule
responder = if request.xhr?
AJAXResponder.new(self)
else
HTMLResponder.new(self)
end
ScheduleInstallation.new(responder).call
end
end

134. LESSONS LEARNED
134

135. Refactoring is Math
135

136. Fast Characterization
Tests Rock
136

137. Embrace Duplication
if request.xhr?
137
0
2
4
6
8
10

138. Embrace Evil Hacks
138

139. Perspective Matters
Superficial design flaws
can conceal
fundamental design flaws
139

140. http://gomakemeasandwich.wordpress.com/2011/10/26/a-yeaf-of-gmmas-where-do-we-go-from-here/
Where Do We Go
From Here?
140

141. 141

142. 142

143. 143

144. http://www.poodr.info/
144

145. Practice!
• Play with automated refactorings in an IDE
• Do them manually in the editor (wax on,
wax off)
145

146. Practice!
• Commit early, commit often:
‘git reset --hard’ is your friend!
• Use throwaway branches
• Write fast characterization tests
146

147. Fluent Refactoring
github.com/geeksam
/fluent-refactoring
Sam Livingston-Gray
geeksam@gmail.com
Twitter, Github: @geeksam
147