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

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

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

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

Algebra ⊂ Math
Math
Algebra
10

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

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

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

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

Math is a Language
Algebra is its Grammar
15

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

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

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

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

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

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

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

"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

Doin It Rong
26

Doin It Rong
27

altering its internal structure without
changing its external behavior."
-refactoring.com
28

http://refactoring.com/
altering its internal structure
without changing its
external behavior."
29

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

restructuring an existing body of
code, altering its internal structure
without changing its external
behavior."
-refactoring.com
31

restructuring an existing body of
code, altering its internal structure
without changing its external
behavior."
32

A technique for
restructuring code
without changing behavior
33

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

Tell a clearer story
with fewer details
35

A language that describes
ways to make your code
suck less.
36

THESISES
THESES
THESII
MY POINT(S)
40

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

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

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

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

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
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
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
end
47

class InstallationsController < ActionController::Base
def schedule
if request.xhr?
begin
render :json => {:errors => ["Cannot schedule installation while credit check is pending"]}, :status => 400
return
end
end
else
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
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
else
end
end
else
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
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

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

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

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

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

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

Replace Method with
Method Object
55

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

def schedule
end
end
class ScheduleInstallation
def call
end
end
# LOTS OF CODE
57

def schedule
end
end
def call
end
end
# LOTS OF CODE
58

def schedule
end
end
def call
end
end
ScheduleInstallation.new.call
# LOTS OF CODE
59

def call
# LOTS OF CODE
end
end
60

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

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

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

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

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

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

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

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

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

if request.xhr?
begin
return
end
#...
end
else
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

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

if request.xhr?
#...
end
else
#...
end
end
if request.xhr?
#...
else
#...
end
73

if request.xhr?
#...
end
else
#...
end
end
75

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

if request.xhr?
return
end
else
redirect_to #...
return
end
end
77

if ajax
if pending_credit_check
return
end
else
redirect_to #...
return
end
end
78

if ajax
return
end
else
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

if ajax
return
end
end
if not ajax
redirect_to #...
return
end
end
if ajax && pending_cred
return
end
if (not ajax) && pendin
redirect_to #...
return
end
80

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

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

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

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

if ajax
else
redirect_to #...
end
return
end
cant_schedule_while_c
return
end
85

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

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

begin
rescue => e
raise e
end
89

begin
begin
rescue
#...
end
rescue => e
raise e
end
90

begin
begin
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

begin
begin
rescue
if request.xhr?
else
end
end
rescue => e
if request.xhr?
raise e
else
raise e
end
end
begin
begin
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

begin
begin
rescue
if request.xhr?
# DO NOTHING
else
end
end
rescue => e
if request.xhr?
else
raise e
end
end
begin
begin
rescue
if request.xhr?
# DO NOTHING
else
# DO NOTHING
end
end
rescue => e
if request.xhr?
else
raise “yak” if Moon
end
end93

begin
begin
rescue
if request.xhr?
# DO NOTHING
else
# DO NOTHING
end
end
rescue => e
if request.xhr?
else
end
end
begin
begin
rescue
# DO NOTHING
end
rescue => e
if request.xhr?
else
end
end
94

begin
begin
rescue
# DO NOTHING
end
rescue => e
if request.xhr?
else
end
end
begin
begin
end
rescue => e
if request.xhr?
else
end
end
95

begin
begin
end
rescue => e
if request.xhr?
else
end
end
begin
rescue => e
if request.xhr?
else
end
end
96

begin
rescue => e
if request.xhr?
else
end
end
begin
rescue => e
handle_exception(e)
end
97

def call
cant_schedule_while_credit_check_pending
return
end
begin
if request.xhr?
end
else
end
end
else
else
end
end
else
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

def call
return
end
begin
if request.xhr?
end
else
end
else
else
end
end
else
end
end
end
handle_exception e
end
end
end
100

def call
return
end
begin
if request.xhr?
if @installation.schedule!(params[:desired_date], :installation_type => params[:installation_type], :city => @city)
end
else
end
else
if @installation.schedule!(params[:desired_date], :installation_type => params[:installation_type], :city => @city)
else
end
end
else
end
end
end
handle_exception e
end
end
end
101

def call
return
end
begin
success = schedule!
if request.xhr?
if success
end
else
end
else
if success
else
end
end
else
end
end
end
handle_exception e
end
end
end
102

def call
return
end
begin
success = schedule!
if success
if request.xhr?
end
else
else
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?
else
end
end
end
handle_exception e
end
end
end
103

def call
return
end
begin
success = schedule!
if success
if request.xhr?
end
else
else
end
end
end
else
scheduling_failed
end
end
handle_exception e
end
end
end
104

def call
return
end
begin
success = schedule!
if success
if request.xhr?
else
else
end
end
end
if request.xhr?
# do nothing
else
end
else
scheduling_failed
end
end
handle_exception e
end
end
end
105

def call
return
end
begin
success = schedule!
if success
scheduling_succeeded
end
if request.xhr?
# do nothing
else
end
else
scheduling_failed
end
end
handle_exception e
end
end
end
106

def call
return
end
begin
success = schedule!
if success
end
do_post_success_cleanup
else
scheduling_failed
end
end
handle_exception e
end
end
end
107

def call
return
end
begin
if schedule!
end
else
scheduling_failed
end
end
handle_exception e
end
end
end
108

def call
return
end
begin
if schedule!
end
else
scheduling_failed
end
end
handle_exception e
end
end
end
request.xhr?
109

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

private
if request.xhr?
render :json => {:errors => [#...
else
redirect_to #...
end
end
end
112

Single Responsibility
Principle
113

ScheduleInstallation
ScheduleInstallationAnd
DoOneThingForAJAXRequestsAnd
DoSomethingElseForHTMLRequests
114

ScheduleInstallation And
DoOneThingForAJAXRequests And
115

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

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

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

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

ScheduleInstallation And
DoOneThingForAJAXRequests And
120

123
InstallationsController
???

124
Responder
???
???

def call
private
def cannot_schedule_while_credit_check_pendin
end
class Responder
end
class ScheduleInstallat
def call
end
class Responder
def cannot_schedule_w
def handle_exception(
def scheduling_succee
def do_post_success_c
end
125

class Responder
def cannot_schedule_while_credit_check_pending
# ...6 lines...
end
if request.xhr?
# ...1 line...
else
# ...2 lines...
end
end
if request.xhr?
# ...7 lines...
else
# ...2 lines...
end
end
if request.xhr?
# ...1 line...
else
# ...2 lines...
end
end
if request.xhr?
# ...2 lines...
else
# ...5 lines...
end
end
if request.xhr?
# NOP
else
# ...2 lines...
end
end
end

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

Replace Conditional
With Polymorphism
129

class Responder
end
class AJAXResponder
def
cannot_schedule_while_cre
def scheduling_succeede
def do_post_success_cle
end
class HTMLResponder
def
cannot_schedule_while_cre
def scheduling_succeede
def do_post_success_cle
end

class AJAXResponder
if request.xhr?
else
redirect_to #...
end
end
end
class HTMLResponder
if request.xhr?
else
redirect_to #...
end
end
end
class AJAXResponder
end
end
class HTMLResponder
redirect_to #...
end
end

132
Responder
???
???

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

Fast Characterization
Tests Rock
136

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

Perspective Matters
Superficial design flaws
can conceal
fundamental design flaws
139

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

http://www.poodr.info/
144

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

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

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

Fluent Refactoring (Lone Star Ruby Conf 2013)

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