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}

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Tuesday, October 22, 13

Math

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\m/


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


http://fanart.tv/fanart/tv/76522/showbackground/the-real-world-4feabd2e9fe60.jpg








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


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

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

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


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

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

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


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








Algebra

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Algebra Isn’t Math

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Algebra Isn’t all of Math

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Algebra ⊂ Math

Math

Algebra

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


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






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


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








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


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



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


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








Math is a Language

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Math is a LanguageAlgebra is[one of]

its Grammar[s]

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Fluent Refactoring

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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?

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Re·fac·tor·ing (noun)

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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

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TL;DR

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

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A techniquefor restructuring code

without changing behavior

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Tell a clearer storywith fewer details

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

Jargon

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Jargon

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A language thatdescribes ways tomake your code

suck less.

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Flu·en·cy (noun)

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

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

with a flashlight in your face

Flu·en·cy (noun)

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

Stress

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Language Hunters

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

Level 1

Level 2

Level 3

Level 4

Levels of Proficiency

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Level 1 Tarzan ata party

“Beer!”“Good party.”

Level 2

Level 3

Level 4


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Level 2 Going tothe party

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

Level 3

Level 4


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Level 3 Discussingthe party

"What happened at the party last night?"

Level 4


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Level 4 Charlie Rose "Should parties be illegal?"


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Level 4 Charlie Rose "Should parties be illegal?"


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Story Time

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Production Rails Code

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Used with:

• Permission


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Used with:

• Permission

• Obfuscation


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Used with:

• Permission

• Obfuscation

• Respect


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Respect

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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

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Observations

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Observations

~800 lines in file

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Observations

~800 lines in file

~50 lines in method

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Observations

~800 lines in file

~50 lines in method

Longest line: 177 chars

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Observations

~800 lines in file

~50 lines in method


Indentation: 4-16 spaces

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Observations

~800 lines in file

~50 lines in method



Nested control structures:

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Observations

~800 lines in file

~50 lines in method




audit_trail_for

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Observations

~800 lines in file

~50 lines in method




audit_trail_for

begin/rescue/end

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Observations

~800 lines in file

~50 lines in method




audit_trail_for

begin/rescue/end

if/else/end

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

Complexity

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http://shipitsquirrel.github.io/

Ship it!

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~800 lines

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

~800 lines

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~800 lines

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~800 lines

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Make the Job Smaller

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Replace Method with Method Object

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See also:

Katrina Owen,“Therapeutic Refactoring”


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

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class InstallationsController < ActionController::Base def schedule

endend

class ScheduleInstallation def call

endend

# LOTS OF CODE

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endend


endend

# LOTS OF CODE

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endend


endend

ScheduleInstallation.new.call

# LOTS OF CODE

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NoMethodErrorLOL WUT?


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

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

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

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

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

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

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def call # LOTS OF CODE end

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

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

Code Archaeology

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

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

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

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

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58

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 => @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



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emph·AS·is

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Flatten Nested Conditionals

source:Michael Feathers

in Dr. Dobbs

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

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ajax nope

TRUE TRUE

ajax nope

FALSE TRUE



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

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

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

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

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

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

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if @installation.pending_credit_check? cant_schedule_while_credit_check_pending returnend

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if @installation.pending_credit_check? cant_schedule_while_credit_check_pending returnend

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

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

“Hard Work” Montage

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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

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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

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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

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request.xhr?

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request.xhr?

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Under The Rug

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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

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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

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












Single Responsibility Principle

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(SRP for short)


ScheduleInstallation

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ScheduleInstallationScheduleInstallationAnd

DoOneThingForAJAXRequestsAndDoSomethingElseForHTMLRequests

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ScheduleInstallationScheduleInstallation And

DoOneThingForAJAXRequests And DoSomethingElseForHTMLRequests

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ScheduleInstallationScheduleInstallation And

DoOneThingForAJAXRequests And DoSomethingElseForHTMLRequests

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Recap

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88

InstallationsController


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88



???


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Responder


???


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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

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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

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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


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Responder


if request.xhr? # do thiselse # do thatend


Replace ConditionalWith Polymorphism

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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 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?

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http://www.poodr.info/99


http://www.poodr.info/

http://www.poodr.info/

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101


102


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Commit Early,Commit Often

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Throw Your Work Away

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Speed Up Your Tests!

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Speed Up Your Tests!See also:

Katrina Owen,“Therapeutic Refactoring”

(srsly)

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107

I work at LivingSocial.We’re hiring.


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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

108

Thanks to:


github.com/geeksam/fluent-refactoring

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github.com/geeksam/fluent-refactoring

Sam [email protected]

Twitter, Github: @geeksam

110


mailto:[email protected]

mailto:[email protected]

Technology

Fluent Refactoring (Cascadia Ruby Conf 2013)