fluent refactoring (lone star ruby conf 2013)
Post on 11-May-2015
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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
48
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
81
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
83
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
84
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
86
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
94
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
95
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
96
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
98
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
99
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
100
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
110
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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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
135
Fast CharacterizationTests Rock
136
Embrace Duplicationif request.xhr?
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0
2
4
6
8
10
Embrace Evil Hacks
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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
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Fluent Refactoringgithub.com/geeksam/fluent-refactoring
Sam Livingston-Graygeeksam@gmail.com
Twitter, Github: @geeksam
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