Fluent Refactoring (Cascadia Ruby Conf 2013)

Fluent Refactoring
Sam Livingston-Gray

THERE
WILL BE
CODE!
It may be
this small

puts (1..100).map { |i|
s = ''
fizz = (i % 3).zero?
buzz = (i % 5).zero?
s << 'Fizz' if fizz
s << 'Buzz' if buzz
s = i if s.empty?
s
}

1
Tuesday, October 22, 13

Math
m/

2

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

4

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

5

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

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

Algebra

7

Algebra Isn’t Math

8

Algebra Isn’t all of Math

9

Algebra ⊂ Math
Algebra

Math
10

11

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

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

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

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

Math is a Language

15

Math is a Language
Algebra is
[one of]
its Grammar[s]

15

Fluent Refactoring

16

17
http://www.kickasslabs.com/2012/04/28/rails-conf-2012-images/100_0304/

Can I get a
deﬁnition?

17
http://www.kickasslabs.com/2012/04/28/rails-conf-2012-images/100_0304/

Re·fac·tor·ing (noun)

18

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

18

TL;DR

19

TL;DR
"...a disciplined technique for
restructuring an existing body of
code, altering its internal structure
without changing its external
behavior."

19

A technique
for restructuring code
without changing behavior

20

Tell a clearer story
with fewer details

21

Jargon

22

http://www.tagxedo.com/app.html


23

A language that
describes ways to
make your code
suck less.
23

Flu·en·cy (noun)

24

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

24

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

25

Stress

26
http://dailyawesimity.ﬁles.wordpress.com/2013/01/cat-stress-relief-4.jpg

Language Hunters

27

Levels of Proﬁciency
Level 1
Level 2
Level 3
Level 4

28

http://www.jamesshore.com/Blog/Proﬁciencies-of-Planning.html

Level 1

Tarzan at
a party

“Beer!”
“Good party.”

Level 2
Level 3
Level 4

29


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
Level 4

30


Level 1

Tarzan at
a party

“Beer!”
“Good party.”

Level 2

Going to
the party


Level 3

Discussing
the party

"What happened at the party
last night?"

Level 4

31


Level 1

Tarzan at
a party

“Beer!”
“Good party.”

Level 2

Going to
the party


Level 3

Discussing
the party

last night?"

Level 4

Charlie Rose

"Should parties be illegal?"

32


Level 1

Tarzan at
a party

“Beer!”
“Good party.”

Level 2

Going to
the party


Level 3

Discussing
the party

last night?"

Level 4

Charlie Rose

"Should parties be illegal?"

33


Level 1

Tarzan at
a party

“Beer!”
“Good party.”

Level 2

Going to
the party


34


Story Time

35

Production Rails Code

36

Used with:

• Permission

36

Used with:

• Permission
• Obfuscation

36

Used with:

• Permission
• Obfuscation
• Respect

36

Respect

37

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


38

Observations


def schedule
if request.xhr?
begin
return
end
end
else
end
end
end
else
end
begin
else
end
end
else
end
end
rescue => e
end
end
end
end


39

Observations


def schedule
if request.xhr?
begin
return
end
end
else
end
end
end
else
end
begin
else
end
end
else
end
end
rescue => e
end
end
end

~800 lines in ﬁle

end


39

Observations


def schedule
if request.xhr?
begin
return
end
end
else
end
end
end
else
end
begin
else
end
end
else
end
end
rescue => e
end
end
end

~800 lines in ﬁle

~50 lines in method

end


39

Observations


def schedule
if request.xhr?
begin
return
end
end
else
end
end
end
else
end
begin
else
end
end
else
end
end
rescue => e
end
end
end

~800 lines in ﬁle

~50 lines in method

Longest line: 177 chars

end


39

Observations


def schedule
if request.xhr?
begin
return
end
end
else
end
end
end
else
end
begin
else
end
end
else
end
end
rescue => e
end
end
end

~800 lines in ﬁle

~50 lines in method

Indentation: 4-16 spaces

end


39

Observations


def schedule
if request.xhr?
begin
return
end
end
else
end
end
end
else
end
begin
else
end
end
else
end
end
rescue => e
end
end
end

~800 lines in ﬁle

~50 lines in method

Nested control
structures:

end


39

Observations


def schedule
if request.xhr?
begin
return
end
end
else
end
end
end
else
end
begin
else
end
end
else
end
end
rescue => e
end
end
end

~800 lines in ﬁle

~50 lines in method

Nested control
structures:
audit_trail_for

end


39

Observations


def schedule
if request.xhr?
begin
return
end
end
else
end
end
end
else
end
begin
else
end
end
else
end
end
rescue => e
end
end
end

~800 lines in ﬁle

~50 lines in method

Nested control
structures:
audit_trail_for

begin/rescue/end

end


39

Observations


def schedule
if request.xhr?
begin
return
end
end
else
end
end
end
else
end
begin
else
end
end
else
end
end
rescue => e
end
end
end

~800 lines in ﬁle

~50 lines in method

Nested control
structures:
audit_trail_for

begin/rescue/end
if/else/end

end


39

Complexity

40
http://scientopia.org/blogs/whitecoatunderground/2009/06/10/my-head-just-asploded-twice/

Ship it!

41

http://shipitsquirrel.github.io/

~800 lines

42

~800 lines

42
http://hyperboleandahalf.blogspot.com/2010/06/this-is-why-ill-never-be-adult.html

~800 lines

43
http://hyperboleandahalf.blogspot.com/2010/06/this-is-why-ill-never-be-adult.html

Make the Job Smaller

44

Replace Method with
Method Object
See also:
Katrina Owen,
“Therapeutic Refactoring”

45

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

46

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

47

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

47

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

47

NoMethodError
LOL WUT?

48

class
def
#
#
#
#
end
end

ScheduleInstallation
call
LOTS OF CODE
... params ...
... render ...
... redirect_to ...

49

def initialize(controller)
@controller = controller
end
def
#
#
#
#
end
end

call
LOTS OF CODE
... params ...
... render ...
... redirect_to ...

50

end
def
#
#
#
#
end
end

call
LOTS OF CODE
... @controller.params ...
... @controller.render ...
... @controller.redirect_to ...

51

end
extend Forwardable
def_delegators :@controller,
:params, :render, :redirect_to
def
#
#
#
#
end
end

call
LOTS OF CODE
... params ...
... render ...
... redirect_to ...

52

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

53

Code Archaeology

54
http://anthro.ucsc.edu/undergraduate/sub-ﬁelds/anthro-archeaology.html

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

55

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

56

begin
#...
end
else
# ...22 lines...
end

57

begin
render :json => #...
return
end
#...
end
else
# ...22 lines...
end

58

begin
return
end
#...
Guard Clause
end
-Smalltalk Best Practice Patterns
else
by Kent Beck
# ...22 lines...
end

58

if request.xhr?
begin
return
end
#...
end
else
flash[:error] = #...
redirect_to installations_path(:city_id =>
end
begin
#...
end
end
59

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

59

if request.xhr?
begin
return
end
#...
end
else
return
end
begin
#...
end
60

if request.xhr?
if request.xhr?
begin
if @installation.pend
if @installation.pending_credit_check? #..
render :json =>
render :json => #... return
return
end
end
begin
#...
#...
end
end
else
else
flash[:error] = #..
redirect_to install
return
return
end
end
begin
begin
#...
#...
end
end
60

if request.xhr?
return
end
begin
#...
end
else
return
end
begin
#...
end
61

if request.xhr?
if request.xhr?
render :json => #..
return
return
end
end
begin
else
#...
end
flash[:error] = #..
else
redirect_to #...
return
flash[:error] = #... end
end
return
end
if request.xhr?
begin
begin
#...
#...
end
end
61

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

62

emph·AS·is

63

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

64

Flatten Nested
Conditionals
source:
Michael Feathers
in Dr. Dobbs

65

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

66

if ajax
if nope
return
end
else
if nope
redirect_to #...
return
end
end

67

if ajax
if nope
return
end
else
if nope
redirect_to #...
return
end
end

67

ajax

nope

TRUE

TRUE

ajax

nope

FALSE

TRUE

if ajax
if nope
return
end
else
if nope
redirect_to #...
return
end
end

68

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

68

if ajax
if nope
return
end
end
if not ajax
if nope
redirect_to #...
return
end
end

69

if ajax
if ajax && nope
if nope
return
end
end
if (not ajax) && nope
end
if not ajax
redirect_to #...
if nope
return
flash[:error] = #...end
redirect_to #...
return
end
end

69

if ajax && nope
return
end
redirect_to #...
return
end

70

if ajax && nope
return
end
redirect_to #...
return
end

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

70

if nope
if ajax
return
end
if not ajax
redirect_to #...
return
end
end

71

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

71

if nope
if ajax
return
else
redirect_to #...
return
end
end

72

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

72

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

73

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

73

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

74

if @installation.pendin
cant_schedule_while_c
if request.xhr?
end
else
redirect_to #...
end
return
end

74

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

75

“Hard Work” Montage

76
http://spectrumculture.com/2012/09/re-makere-model-the-karate-kid-1984-vs-the-karate-kid-2010.html/

def schedule
if request.xhr?
begin
return
end
end
else
end
end
end
else
end
begin
else
end
end
else
end
end
rescue => e
end
end
end
end

77

def schedule
if request.xhr?
begin
return
end
end
else
end
end
end
else
end
begin
else
end
end
else
end
end
rescue => e
end
end
end
end

def call
if @installation.pending_c
cant_schedule_while_cred
return
end

77

audit_trail_for(current_us
if schedule!
if @installation.sched
scheduling_succeeded
end
do_post_success_cleanu
else
scheduling_failed
end
end
rescue => e
handle_exception e
end
end

def call
return
end
if schedule!
end
do_post_success_cleanup
else
scheduling_failed
end
end
rescue => e
handle_exception e
end
end
78


def call
return
end
if schedule!
end
else
scheduling_failed
end
end
rescue => e
handle_exception e
end
end

request.xhr?

79


Under The Rug

80

def cannot_schedule_while_#...
if request.xhr?
# ...1 line...
else
# ...2 lines...
end
end

def scheduling_failed
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 do_post_success_cleanup
if request.xhr?
# DO NOTHING
else
# ...1 line...
end
end

def scheduling_succeeded
if request.xhr?
# ...2 lines...
else
# ...5 lines...
end
end
81

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


Single Responsibility
Principle
(SRP for short)

83


84

ScheduleInstallationAnd
DoOneThingForAJAXRequestsAnd
DoSomethingElseForHTMLRequests

84

ScheduleInstallation And

DoOneThingForAJAXRequests And

85

ScheduleInstallation And
DoOneThingForAJAXRequests And

86

Recap

87

InstallationsController

88



88

???

88


Responder
???

89

???
Responder
???

89

def call
private
def
def
def
def
def
end

cannot_schedule_while_credit_check_pendin
handle_exception(e)
scheduling_failed

class Responder
end

90

class ScheduleInstallat
def call
def call
end
private
class Responder
def cannot_schedule_while_credit_check_pendin
def cannot_schedule_w
def handle_exception(e) def handle_exception(
def scheduling_succeededdef scheduling_succee
def do_post_success_cleanup do_post_success_c
def
end
end
class Responder
end

90

Responder

91

if request.xhr?
# do this
else
# do that
end

Replace Conditional
With Polymorphism

93

class
def
def
def
def
def
end


Responder
cannot_schedule_while_credit_check_pending
handle_exception(e)
scheduling_failed

class
def
def
def
def
def
end

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

class HTMLResponder
def
cannot_schedule_while_cre
def scheduling_succeede
def do_post_success_cle
end

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

Where Do We Go
From Here?

98
http://gomakemeasandwich.wordpress.com/2011/10/26/a-yeaf-of-gmmas-where-do-we-go-from-here/

99

http://www.poodr.info/

Commit Early,
Commit Often

104

Throw Your Work Away

105

Speed Up Your Tests!

106

Speed Up Your Tests!
See also:
Katrina Owen,
“Therapeutic Refactoring”
(srsly)

106

I work at LivingSocial.
We’re hiring.

107

I work at LivingSocial.
We’re hiring.
(Who isn’t?)

107

Thanks to:
Jim Shore and Diana Larsen
for “Agile Fluency”
Kirsten Comandich
Sandi Metz, Katrina Owen,
Sonia Connolly
PDX.rb
108

github.com/geeksam
/fluent-refactoring

109

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

110

Fluent Refactoring (Cascadia Ruby Conf 2013)

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