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Fluency is "what you can say without having to think about how to say it." "Refactoring" is a language that describes ways to make your code better. I want to inspire you to learn more of that language, so you can make your code better without having to think about it. I'll walk you through the process of reworking a 50-line controller action that's hard to comprehend, let alone refactor. We'll tease apart fiendishly intertwined structures, embrace duplication, use dirty tricks to our advantage, and uncover responsibilities—and bugs!—that weren't obvious at first glance.
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Fluent RefactoringSam Livingston-Gray
THERE WILL BE CODE!
It may bethis 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 send
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Let’s Talk About Math!
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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
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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/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 LanguageAlgebra is its Grammar
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Dick and Jane
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Fluent Refactoring
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http://www.kickasslabs.com/2012/04/28/rails-conf-2012-images/100_0304/
Can I get a definition?
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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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http://www.jamesshore.com/Blog/Proficiencies-of-Planning.html
Level 1 Tarzan ata party
“Beer!”“Good party.”
Level 2 Going tothe party
"Where is the party?""How do I get to the party?"
Level 3 Discussingthe party
"What happened at the party last night?"
Level 4 Charlie Rose "Should parties be illegal?"
Levels of Proficiency
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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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http://refactoring.com/
"...a disciplined technique for restructuring an existing body of code, altering its internal structure without changing its external behavior."
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"Yeah, we're going to have to takea couple of weeks out of the schedule for refactoring, and that's probably going
to break some stuff."
Doin It Rong
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"Yeah, we're going to have to takea couple of weeks out of the schedule for refactoring, and that's probably going
to break some stuff."
Doin It Rong
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"Yeah, we're going to have to takea couple of weeks out of the schedule for refactoring, and that's probably going
to break some stuff."
Doin It Rong
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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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http://refactoring.com/
"...a disciplined technique for restructuring an existing body of code, altering its internal structure
without changing its external behavior."
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Tests are implied.-Katrina Owen,
“Therapeutic Refactoring”
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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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Re·fac·tor·ing (noun)"...a disciplined technique for restructuring an existing body of code, altering its internal structure without changing its external behavior."
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Re·fac·tor·ing (noun)
A technique forrestructuring code
without changing behavior
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Re·fac·tor (verb)
To restructure codewithout changing behavior
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Tell a clearer storywith fewer details
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Re·fac·tor·ing (noun)
A language that describes ways to make your code
suck less.
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THESISES
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THESISESTHESES
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THESISESTHESESTHESII
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THESISESTHESESTHESII
MY POINT(S)
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You're probably already fluent in refactoring.
Level 1:Rename Variable; Rename Method.
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You can become more fluent in refactoring.
It just takes practice.
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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.
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Refactoring Session
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Used with:
• Permission
• Obfuscation
• Respect
Production Rails Code
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Schedule Cable Installs
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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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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
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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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http://shipitsquirrel.github.io/
Ship Shit!
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http://hyperboleandahalf.blogspot.com/2010/06/this-is-why-ill-never-be-adult.html
~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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Make the Job Smaller
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Replace Method with Method Object
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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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class InstallationsController < ActionController::Base def schedule
endend
class ScheduleInstallation def call
endend
# LOTS OF CODE
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class InstallationsController < ActionController::Base def schedule
endend
class ScheduleInstallation def call
endend
ScheduleInstallation.new.call
# LOTS OF CODE
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class ScheduleInstallation def call # LOTS OF CODE endend
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class ScheduleInstallation def initialize(controller) @controller = controller end
def call # LOTS OF CODE endend
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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) endend
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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 if @installation.pending_credit_check? render :json => #... return end #... endelse # ...22 lines...end
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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 #...end
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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 #...end
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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 #...end
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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 #...end
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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 endelse if @installation.pending_credit_check? flash[:error] = #... redirect_to(...) and return return endend
if request.xhr? #...else #...71
if request.xhr? #...else #...end
if request.xhr? #...else #...end
ZOMGduplication!!!1!!
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if request.xhr? if @installation.pending_credit_check? #... endelse if @installation.pending_credit_check? #... endend
if request.xhr? #...else #...end
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Emphasis
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if request.xhr? if @installation.pending_credit_check? #... endelse if @installation.pending_credit_check? #... endend
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Flatten Nested Conditionals
source: Michael Feathers,writing for Dr. Dobbs
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if request.xhr? if @installation.pending_credit_check? render :json => #... return endelse if @installation.pending_credit_check? flash[:error] = #... redirect_to #... return endend
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if ajax if pending_credit_check render :json => #... return endelse if pending_credit_check flash[:error] = #... redirect_to #... return endend
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if ajax if pending_credit_check render :json => #... return endelse if pending_credit_check flash[:error] = #... redirect_to #... return endend
if ajax if pending_credit_check render :json => #... return endendif not ajax if pending_credit_check flash[:error] = #... redirect_to #... return endend
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if ajax if pending_credit_check render :json => #... return endendif not ajax if pending_credit_check flash[:error] = #... redirect_to #... return endend
if ajax && pending_credit_check render :json => #... returnendif (not ajax) && pending_credit_check flash[:error] = #... redirect_to #... returnend
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if ajax && pending_credit_check render :json => #... returnendif (not ajax) && pending_credit_check flash[:error] = #... redirect_to #... returnend
if pending_credit_check if ajax render :json => #... return end if not ajax flash[:error] = #... redirect_to #... return endend
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if pending_credit_check if ajax render :json => #... return end if not ajax flash[:error] = #... redirect_to #... return endend
if pending_credit_check if ajax render :json => #... return else flash[:error] = #... redirect_to #... return endend
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if pending_credit_check if ajax render :json => #... return else flash[:error] = #... redirect_to #... return endend
if pending_credit_check if ajax render :json => #... else flash[:error] = #... redirect_to #... end returnend
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if ajax if pending_credit_check render :json => #... return endelse if pending_credit_check flash[:error] = #... redirect_to #... return endend
if pending_credit_check if ajax render :json => #... else flash[:error] = #... redirect_to #... end returnend
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if pending_credit_check if ajax render :json => #... else flash[:error] = #... redirect_to #... end returnend
if pending_credit_check cant_schedule_while_credit_check_pending returnend
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Exception Handling
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raise “wtf” if coin.toss.heads?begin raise “wtf” if coin.toss.heads?end
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begin raise “wtf” if coin.toss.heads?end
begin raise “wtf” if coin.toss.heads?rescue => e raise eend
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begin raise “wtf” if coin.toss.heads?rescue => e raise eend
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begin begin raise “wtf” if coin.toss.heads? rescue #... endrescue => e raise eend
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begin begin raise “wtf” if coin.toss.heads? rescue if request.xhr? raise “tfw” if tuesday? else raise “yak” if Moon.gibbous? end endrescue => e raise eend
begin begin raise “wtf” if coin.toss.heads? rescue if request.xhr? raise “tfw” if tuesday? else raise “yak” if Moon.gibbous? end endrescue => e if request.xhr? raise e else raise e endend91
begin begin raise “wtf” if coin.toss.heads? rescue if request.xhr? raise “tfw” if tuesday? else raise “yak” if Moon.gibbous? end endrescue => e if request.xhr? raise e else raise e endend
begin begin raise “wtf” if coin.toss.heads? rescue if request.xhr? # DO NOTHING else raise “yak” if Moon.gibbous? end endrescue => e if request.xhr? raise “tfw” if tuesday? else raise e endend92
begin begin raise “wtf” if coin.toss.heads? rescue if request.xhr? # DO NOTHING else raise “yak” if Moon.gibbous? end endrescue => e if request.xhr? raise “tfw” if tuesday? else raise e endend
begin begin raise “wtf” if coin.toss.heads? rescue if request.xhr? # DO NOTHING else # DO NOTHING end endrescue => e if request.xhr? raise “tfw” if tuesday? else raise “yak” if Moon.gibbous? endend93
begin begin raise “wtf” if coin.toss.heads? rescue if request.xhr? # DO NOTHING else # DO NOTHING end endrescue => e if request.xhr? raise “tfw” if tuesday? else raise “yak” if Moon.gibbous? endend
begin begin raise “wtf” if coin.toss.heads? rescue # DO NOTHING endrescue => e if request.xhr? raise “tfw” if tuesday? else raise “yak” if Moon.gibbous? endend
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begin begin raise “wtf” if coin.toss.heads? rescue # DO NOTHING endrescue => e if request.xhr? raise “tfw” if tuesday? else raise “yak” if Moon.gibbous? endend
begin begin raise “wtf” if coin.toss.heads? endrescue => e if request.xhr? raise “tfw” if tuesday? else raise “yak” if Moon.gibbous? endend
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begin begin raise “wtf” if coin.toss.heads? endrescue => e if request.xhr? raise “tfw” if tuesday? else raise “yak” if Moon.gibbous? endend
begin raise “wtf” if coin.toss.heads?rescue => e if request.xhr? raise “tfw” if tuesday? else raise “yak” if Moon.gibbous? endend
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begin raise “wtf” if coin.toss.heads?rescue => e if request.xhr? raise “tfw” if tuesday? else raise “yak” if Moon.gibbous? endend
begin raise “wtf” if coin.toss.heads?rescue => e handle_exception(e)end
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Training Montage
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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 endend
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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 endend
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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 endend
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 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 endend
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 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 endend
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 scheduling_failed end end rescue Exception => e handle_exception e end endend
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 @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 endend
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 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 endend
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 do_post_success_cleanup else scheduling_failed end end rescue Exception => e handle_exception e end endend
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 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 endend
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 endend
request.xhr?
109
Under The Rug
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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
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class ScheduleInstallation private
def scheduling_failed if request.xhr? render :json => {:errors => [#... else flash[:error] = #... redirect_to #... end endend
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Single Responsibility Principle
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ScheduleInstallationScheduleInstallationAnd
DoOneThingForAJAXRequestsAndDoSomethingElseForHTMLRequests
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ScheduleInstallationScheduleInstallation And
DoOneThingForAJAXRequests AndDoSomethingElseForHTMLRequests
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“Methods, like classes, should have a single
responsibility.”-Sandi Metz
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http://en.wikipedia.org/wiki/File:Bill_%26_Ted%27s_Excellent_Adventure_(Original_Motion_Picture_Soundtrack).jpg117
http://en.wikipedia.org/wiki/File:Paris_Tuileries_Garden_Facepalm_statue.jpg118
Single Responsibility Principle
Every class should have a single responsibility, and that responsibility
should be entirely encapsulatedby the class.
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ScheduleInstallationScheduleInstallation And
DoOneThingForAJAXRequests AndDoSomethingElseForHTMLRequests
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Responder
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122
InstallationsController
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InstallationsController
ScheduleInstallation???
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InstallationsController
Responder
???
ScheduleInstallation???
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_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
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126
Dualism
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
if request.xhr? # do fooelse # do barend
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 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 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
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InstallationsController
Responder
???
ScheduleInstallation???
class InstallationsController < ActionController::Base
def schedule responder = if request.xhr? AJAXResponder.new(self) else HTMLResponder.new(self) end ScheduleInstallation.new(responder).call endend
LESSONS LEARNED
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Refactoring is Math
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Fast CharacterizationTests Rock
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Embrace Duplicationif request.xhr?
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0
2
4
6
8
10
Embrace Evil Hacks
138
Perspective MattersSuperficial design flaws
can concealfundamental design flaws
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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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141
142
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Practice!• Play with automated refactorings in an IDE
• Do them manually in the editor (wax on, wax off)
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Practice!• Commit early, commit often:
‘git reset --hard’ is your friend!
• Use throwaway branches
• Write fast characterization tests
146
Fluent Refactoringgithub.com/geeksam/fluent-refactoring
Twitter, Github: @geeksam
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![Refactoring Neural Networks for Verification · Refactoring for Verification: To achieve this we adapt the concept of refactoring to deep neural networks. Code refactoring [32]](https://img.dokumen.tips/doc/110x75/5f99f55ef5020022ff11f3a9/refactoring-neural-networks-for-veriication-refactoring-for-veriication-to.jpg)
