Refactoring

Refactoring { :from => :mess, :to => :clean_code, :through => :patterns } @caike Orlando Ruby User Group http://caikesouza.com January 2010 Friday, January 15, 2010

Agile Friday, January 15, 2010

Testing Friday, January 15, 2010

Patterns Friday, January 15, 2010

Professionalism Friday, January 15, 2010

Software Craftsmanship Friday, January 15, 2010

? Friday, January 15, 2010

http://www.ﬂickr.com/photos/eurleif/255241547/ Friday, January 15, 2010

"Any fool can write code that a computer can understand. Good programmers write code that humans can understand" (Martin Fowler) Friday, January 15, 2010

“Free software only matters to those who can read” (Robert M. Lefkowitz) Friday, January 15, 2010

Friday, January 15, 2010

http://www.ﬂickr.com/photos/dhammza/91435718/ Friday, January 15, 2010

Given messy code that works When I refactor Then it should be easier to understand And still work! Friday, January 15, 2010

Cleaning up the house Friday, January 15, 2010

http://www.ﬂickr.com/photos/benfrantzdale/208672143/ http://www.ﬂickr.com/photos/improveit/1574023621/ Friday, January 15, 2010

wiki, Fit, JUnit http://www.ﬂickr.com/photos/benfrantzdale/208672143/ eXtreme Programming http://www.ﬂickr.com/photos/improveit/1574023621/ Friday, January 15, 2010

Friday, January 15, 2010

http://www.ﬂickr.com/photos/adewale_oshineye/2933030620 Friday, January 15, 2010

Some reasons... Friday, January 15, 2010

Design++ Friday, January 15, 2010

Money++ Friday, January 15, 2010

Respond to changes Money++ Friday, January 15, 2010

Respond to changes Money++ Release with conﬁdence Friday, January 15, 2010

Effort-- Friday, January 15, 2010

Waterfall Jan Feb Mar Apr May Jun Jul Cost of Maintenance Extreme Programming Explained: Embrace Change Addison Wesley, 2000 Friday, January 15, 2010

XP Jan Feb Mar Apr May Jun Jul Cost of Maintenance Extreme Programming Explained: Embrace Change Addison Wesley, 2000 Friday, January 15, 2010

code LESS sleep MORE http://www.ﬂickr.com/photos/x180/503574487/ Friday, January 15, 2010

http://www.ﬂickr.com/photos/rockinrob/1485573200/ Friday, January 15, 2010

When ? Friday, January 15, 2010

When you add a function Friday, January 15, 2010

When you ﬁx a bug Friday, January 15, 2010

Code Reviews Friday, January 15, 2010

http://www.ﬂickr.com/photos/highwayoﬂife/2699887178/ Friday, January 15, 2010

Code Smells Friday, January 15, 2010

Duplicated Code Code Smells Friday, January 15, 2010

Duplicated Code Code Smells Long Method Friday, January 15, 2010

Duplicated Code Large Class Code Smells Long Method Friday, January 15, 2010

Duplicated Code Large Class Divergent Change Code Smells Long Method Friday, January 15, 2010

Duplicated Code Large Class Divergent Change Code Smells Long Parameter List Long Method Friday, January 15, 2010

Test Driven Development Friday, January 15, 2010

Red Green Refactor Friday, January 15, 2010

What if I Don’t ? Friday, January 15, 2010

Debt Metaphor Friday, January 15, 2010

http://www.ﬂickr.com/photos/benfrantzdale/208672143/ Friday, January 15, 2010

http://www.ﬂickr.com/photos/didmyself/3050138294/ Friday, January 15, 2010

Get ready for code! Friday, January 15, 2010

managers = [] employees.each do |e| managers << e if e.is_manager? end Saturday, January 16, 2010

Replace Loop with Closure Method Saturday, January 16, 2010

managers = [] employees.each do |e| managers << e if e.is_manager? end Saturday, January 16, 2010

managers = employees. select { |e| e.is_manager? } Saturday, January 16, 2010

class Movie def initialize(stars) @stars = stars end def recommended? ((@stars > 5) ? 8 : 1) >= 8 end end Saturday, January 16, 2010

http://www.ﬂickr.com/photos/anirudhkoul/3804552280/ Saturday, January 16, 2010

http://www.bartcop.com/marilyn-monroe001.jpg Saturday, January 16, 2010

http://thetorchonline.com/wp-content/uploads/2009/04/deathstar.jpg Saturday, January 16, 2010

Introduce Explaining Variable Saturday, January 16, 2010

class Movie def initialize(stars) @stars = stars end def recommended? rating = (@stars > 5) ? 8 : 1 rating >= 8 end end Saturday, January 16, 2010

Replace Temp With Query Saturday, January 16, 2010

class Movie def initialize(stars) @stars = stars end def recommended? rating = (@stars > 5) ? 8 : 1 rating >= 8 end end Saturday, January 16, 2010

class Movie def initialize(stars) @stars = stars end def recommended? rating >= 8 end def rating (@stars > 5) ? 8 : 1 end end Saturday, January 16, 2010

OMG, This is sooooo cooooool! Saturday, January 16, 2010

class Movie def recommended? rating >= 8 end def rating (@stars > 5) ? 8 : 1 end end Saturday, January 16, 2010

class Movie def recommended? rating >= 8 end def rating more_than_five_stars? ? 8 : 1 end def more_than_five_stars? @stars > 5 end end Saturday, January 16, 2010

Inline Method Saturday, January 16, 2010

class Movie def initialize...end def recommended? rating >= 8 end def rating more_than_five_stars? ? 8 : 1 end def more_than_five_stars? @stars > 5 end end Saturday, January 16, 2010

class Movie def initialize...end def recommended? rating >= 8 end def rating @stars > 5 ? 8 : 1 end end Saturday, January 16, 2010

mock = mock('user') expectation = mock.expects(:find) expectation.with("1") expectation.returns([]) Saturday, January 16, 2010

Replace Temp With Chain Saturday, January 16, 2010

mock = mock('user') expectation = mock.expects(:find) expectation.with("1") expectation.returns([]) Saturday, January 16, 2010

mock = mock('user') mock.expects(:find).with("1"). returns([]) Saturday, January 16, 2010

def expects ... self end def with ... self end def returns ... self end Saturday, January 16, 2010

def charge(amount, ccnumber) begin conn = CC_Charger_Server.connect(...) conn.send(amount, ccnumber) rescue IOError => e Logger.log "Error: #{e}" return nil ensure conn.close end end Saturday, January 16, 2010

Extract Surrounding Method Saturday, January 16, 2010

def charge(amount, ccnumber) begin conn = CC_Charger_Server.connect(...) conn.send(amount, ccnumber) rescue IOError => e Logger.log "Error: #{e}" return nil ensure conn.close end end Saturday, January 16, 2010

def charge(amount, ccnumber) connect do |conn| conn.send(amount, ccnumber) end end Saturday, January 16, 2010

def connect begin conn = CC_Charger_Server.connect(...) yield conn rescue IOError => e Logger.log "Error: #{e}" return nil ensure conn.close end end Saturday, January 16, 2010

def body_fat_percentage(name, age, height, weight, metric_system) ... end Saturday, January 16, 2010

body_fat_percentage("fred", 30, 1.82, 90, 1) body_fat_percentage("joe", 32, 6, 220, 2) Saturday, January 16, 2010

Introduce Named Parameter Saturday, January 16, 2010

def body_fat_percentage(name, age, height, weight, metric_system) ... end Saturday, January 16, 2010

def body_fat_percentage(name, params={}) # params[:age] # params[:height] # params[:weight] # params[:metric_system] end Saturday, January 16, 2010

body_fat_percentage("fred", 30, 1.82, 90, 1) body_fat_percentage("joe", 32, 6, 220, 2) Saturday, January 16, 2010

body_fat_percentage("fred", :age => 30, :height => 1.82, :weight => 90, MetricSystem::METERS_KG) body_fat_percentage("joe", :age => 32, :height => 6, :weight => 220, MetricSystem::FEET_LB) Saturday, January 16, 2010

user.posts.paginate(:page => params[:page], :per_page => params[:per_page] || 15) Saturday, January 16, 2010

Replace Magic Number with Symbolic Constant Saturday, January 16, 2010

user.posts.paginate(:page => params[:page], :per_page => params[:per_page] || 15) Saturday, January 16, 2010

CONTACTS_PER_PAGE = 15 user.posts.paginate(:page => params[:page], :per_page => params[:per_page] || CONTACTS_PER_PAGE) Saturday, January 16, 2010

class MountainBike def price ... end end MountainBike.new(:type => :rigid, ...) MountainBike.new(:type => :front_suspension, ...) MountainBike.new(:type => :full_suspension, ...) Saturday, January 16, 2010

def price if @type_code == :rigid (1 + @comission) * @base_price end if @type_code == :font_suspension (1 + @comission) * @base_price + @front_suspension_price end if @type_code == :full_suspension (1 + @comission) * @base_price+ @front_suspension_price + @rear_suspension_price end end Saturday, January 16, 2010

def price if @type_code == :rigid (1 + @comission) * @base_price end if @type_code == :font_suspension (1 + @comission) * @base_price + @front_suspension_price end if @type_code == :full_suspension (1 + @comission) * @base_price+ @front_suspension_price + @rear_suspension_price end if @type_code == :ultra_suspension ... end end Saturday, January 16, 2010

Saturday, January 16, 2010

Replace Conditional With Polymorphism Saturday, January 16, 2010

class MountainBike def price ... end end Saturday, January 16, 2010

module MountainBike def price ... end end Saturday, January 16, 2010

class RigidMountainBike include MountainBike end class FrontSuspensionMountainBike include MountainBike end class FullSuspensionMountainBike include MountainBike end Saturday, January 16, 2010

RigidMountainBike.new(:type => :rigid, ...) FrontSuspensionMountainBike.new(:type => :front_suspension, ...) FullSuspensionMountainBike.new(:type => :full_suspension, ...) Saturday, January 16, 2010

class RigidMountainBike include MountainBike def price (1 + @comission) * @base_price end end Saturday, January 16, 2010

def price if @type_code == :rigid raise "should not be called" end if @type_code == :font_suspension (1 + @comission) * @base_price + @front_suspension_price end if @type_code == :full_suspension (1 + @comission) * @base_price+ @front_suspension_price + @rear_suspension_price end end Saturday, January 16, 2010

class FrontSuspensionMountainBike include MountainBike def price (1 + @comission) * @base_price + @front_suspension_price end end class FullSuspensionMountainBike include MountainBike def price (1 + @comission) * @base_price + @front_suspension_price + @rear_suspension_price end end Saturday, January 16, 2010

def price if @type_code == :rigid raise "should not be called" end if @type_code == :font_suspension raise "should not be called" end if @type_code == :full_suspension raise "should not be called" end end Saturday, January 16, 2010

class RigidMountainBike include MountainBike end class FrontSuspensionMountainBike include MountainBike end class FullSuspensionMountainBike include MountainBike end Saturday, January 16, 2010

Only the beginning... Saturday, January 16, 2010

Coding Dojo http://www.ﬂickr.com/photos/el_ser_lomo/3267627038/ http://orlandodojo.wordpress.com/ http://groups.google.com/group/orlando-dojo/ Saturday, January 16, 2010

Saturday, January 16, 2010

Thank you! @caike http://caikesouza.com Saturday, January 16, 2010

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Refactoring

by Caike Souza on Jan 15, 2010

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Refactoring — Presentation Transcript