Fluent Refactoring (Cascadia Ruby Conf 2013)

Fluent RefactoringSam Livingston-Gray

THERE WILL BE CODE!

It may bethis 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}

Tuesday, October 22, 13

http://2012books.lardbucket.org/books/elementary-algebra/section_06/5d10b670d78abac93a4572dc0c2afb0f.jpg3

http://www.wikihow.com/Image:Solve-for-X-Step-12.jpg4

http://math.about.com/od/algebra/ss/birthday.htm5

http://www.smosh.com/smosh-pit/photos/16-wonderfully-stupid-test-answers6

Algebra

Algebra Isn’t Math

Algebra Isn’t all of Math

Algebra ⊂ Math

Algebra

http://upload.wikimedia.org/wikipedia/commons/thumb/0/08/NautilusCutawayLogarithmicSpiral.jpg/793px-NautilusCutawayLogarithmicSpiral.jpg11

http://upload.wikimedia.org/wikipedia/commons/a/a4/Mandelbrot_sequence_new.gif12

http://mathequalslove.blogspot.com/2012/12/hexaflexagon-love.html13

http://think-like-a-git.net/sections/graph-theory/seven-bridges-of-konigsberg.html14

Math is a Language

Math is a LanguageAlgebra is[one of]

its Grammar[s]

Fluent Refactoring

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

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

Can I get a definition?

Re·fac·tor·ing (noun)

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

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

A techniquefor restructuring code

without changing behavior

Tell a clearer storywith fewer details

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

Jargon

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

Jargon

A language thatdescribes ways tomake your code

suck less.

Flu·en·cy (noun)

Flu·en·cy (noun)What you can say when you’renot thinking about how to say it

What you can say when you’rewoken up in the middle of the night

with a flashlight in your face

Flu·en·cy (noun)

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

Stress

Language Hunters

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

Level 1

Level 2

Level 3

Level 4

Levels of Proficiency

Level 1 Tarzan ata party

“Beer!”“Good party.”

Level 2

Level 3

Level 4

Level 2 Going tothe party

"Where is the party?""How do I get to the party?"

Level 3

Level 4

Level 3 Discussingthe party

"What happened at the party last night?"

Level 4

Level 4 Charlie Rose "Should parties be illegal?"

Story Time

Production Rails Code

Used with:

• Permission

Used with:

• Permission

• Obfuscation

Used with:

• Permission

• Obfuscation

• Respect

Respect

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

Observations

~800 lines in file

~50 lines in method

Observations

~800 lines in file

~50 lines in method

Longest line: 177 chars

Observations

~800 lines in file

~50 lines in method

Indentation: 4-16 spaces

Observations

~800 lines in file

~50 lines in method

Nested control structures:

Observations

~800 lines in file

~50 lines in method

audit_trail_for

Observations

~800 lines in file

~50 lines in method

audit_trail_for

begin/rescue/end

Observations

~800 lines in file

~50 lines in method

audit_trail_for

begin/rescue/end

if/else/end

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

Complexity

http://shipitsquirrel.github.io/

Ship it!

~800 lines

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

~800 lines

Make the Job Smaller

Replace Method with Method Object

See also:

Katrina Owen,“Therapeutic Refactoring”

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

class InstallationsController < ActionController::Base def schedule

endend

class ScheduleInstallation def call

endend

# LOTS OF CODE

endend

# LOTS OF CODE

endend

ScheduleInstallation.new.call

# LOTS OF CODE

NoMethodErrorLOL WUT?

class ScheduleInstallation def call # LOTS OF CODE # ... params ... # ... render ... # ... redirect_to ... endend

class ScheduleInstallation def initialize(controller) @controller = controller end

def call # LOTS OF CODE # ... params ... # ... render ... # ... redirect_to ... endend

def call # LOTS OF CODE # ... @controller.params ... # ... @controller.render ... # ... @controller.redirect_to ... endend

extend Forwardable def_delegators :@controller, :params, :render, :redirect_to

def call # LOTS OF CODE # ... params ... # ... render ... # ... redirect_to ... endend

def call # LOTS OF CODE end

def method_missing(m, *a, &b) @controller.send(m, *a, &b) endend

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

Code Archaeology

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

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

if request.xml_http_request? begin #... endelse # ...22 lines...end

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

Guard Clause-Smalltalk Best Practice Patterns

by Kent Beck

if request.xhr? begin if @installation.pending_credit_check? render :json => #... return end #... endelse if @installation.pending_credit_check? flash[:error] = #... redirect_to installations_path(:city_id => @installation.city_id, :view => "calendar") and return end begin #... endend 59

if request.xhr? begin if @installation.pending_credit_check? render :json => #... return end #... endelse if @installation.pending_credit_check? flash[:error] = #... redirect_to installations_path(:city_id => return end begin #... end 60

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

if request.xhr? if @installation.pending_credit_check? render :json => #... return end begin #... endelse if @installation.pending_credit_check? flash[:error] = #... redirect_to installations_path( return end begin #... end60

if request.xhr? if @installation.pending_credit_check? render :json => #... return end begin #... endelse if @installation.pending_credit_check? flash[:error] = #... redirect_to installations_path(:city_id => return end begin #... end 61

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

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

if request.xhr? begin #... end61

emph·AS·is

Flatten Nested Conditionals

source:Michael Feathers

in Dr. Dobbs

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

ajax nope

TRUE TRUE

ajax nope

FALSE TRUE

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

if ajax && nope render :json => #... returnendif (not ajax) && nope flash[:error] = #... redirect_to #... returnend

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

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

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

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

if @installation.pending_credit_check? cant_schedule_while_credit_check_pending returnend

if request.xhr? begin #... endelse begin #... endend

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

“Hard Work” Montage

class InstallationsController < ActionController::Base 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 endend

class ScheduleInstallation def call if @installation.pending_credit_check? cant_schedule_while_credit_check_pending return end

audit_trail_for(current_user) if schedule! if @installation.scheduled_date scheduling_succeeded end do_post_success_cleanup else scheduling_failed end end rescue => e handle_exception e endend

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 => e handle_exception e endend

request.xhr?

Under The Rug

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

def handle_exception(e) if request.xhr? # ...7 lines... else # ...2 lines... endend

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

def scheduling_failed if request.xhr? # ...1 line... else # ...2 lines... endend

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

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

def handle_exception(e) if request.xhr? # ...7 lines... else # ...2 lines... endend

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

def scheduling_failed if request.xhr? # ...1 line... else # ...2 lines... endend

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

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

Single Responsibility Principle

(SRP for short)

ScheduleInstallation

ScheduleInstallationScheduleInstallationAnd

DoOneThingForAJAXRequestsAndDoSomethingElseForHTMLRequests

ScheduleInstallationScheduleInstallation And

DoOneThingForAJAXRequests And DoSomethingElseForHTMLRequests

ScheduleInstallationScheduleInstallation And

DoOneThingForAJAXRequests And DoSomethingElseForHTMLRequests

InstallationsController

Responder

private

def cannot_schedule_while_credit_check_pendin def handle_exception(e) def scheduling_failed def scheduling_succeeded def do_post_success_cleanupend

class Responderend

private

def cannot_schedule_while_credit_check_pendin def handle_exception(e) def scheduling_failed def scheduling_succeeded def do_post_success_cleanupend

class Responderend

class ScheduleInstallation def callend

class Responder def cannot_schedule_while_credit_check_pe def handle_exception(e) def scheduling_failed def scheduling_succeeded def do_post_success_cleanupend

Responder

if request.xhr? # do thiselse # do thatend

Replace ConditionalWith Polymorphism

class Responder def cannot_schedule_while_credit_check_pending def handle_exception(e) def scheduling_failed def scheduling_succeeded def do_post_success_cleanupend

class AJAXResponder def cannot_schedule_while_credit_check_pending def handle_exception(e) def scheduling_failed def scheduling_succeeded def do_post_success_cleanupend

class HTMLResponder def cannot_schedule_while_credit_check_pending def handle_exception(e) def scheduling_failed def scheduling_succeeded def do_post_success_cleanupend

class InstallationsController < ActionController::Base

def schedule responder = request.xhr? ? AJAXResponder.new(self) : HTMLResponder.new(self) ScheduleInstallation.new(responder).call endend

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

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

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

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

class AJAXResponder def scheduling_failed render :json => #... endend

class HTMLResponder def scheduling_failed flash[:error] = #... redirect_to #... endend

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

Where Do We Go From Here?

http://www.poodr.info/99

Commit Early,Commit Often

Throw Your Work Away

Speed Up Your Tests!

Speed Up Your Tests!See also:

Katrina Owen,“Therapeutic Refactoring”

(srsly)

I work at LivingSocial.We’re hiring.

(Who isn’t?)

Jim Shore and Diana Larsenfor “Agile Fluency”

Kirsten Comandich

Sandi Metz, Katrina Owen,Sonia Connolly

PDX.rb

Thanks to:

github.com/geeksam/fluent-refactoring

Sam Livingston-Graygeeksam@gmail.com

Twitter, Github: @geeksam

Fluent Refactoring (Cascadia Ruby Conf 2013)

Technology

Cascadia Cargo Cooperative

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California Cascadia Subduction Zone Earthquake and …temp.caloes.ca.gov/PlanningPreparednessSite/Documents/Cascadia... · California Cascadia Subduction Zone Earthquake and Tsunami

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CASCADIA WALLPAPER

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