This document discusses various code optimization strategies for Ruby, aimed at improving performance and efficiency by reducing resource usage and enhancing developer experience. Key optimizations include using interpolation over concatenation, destructive operations, benchmarking, using symbols, and simplifying comparisons with ranges. It emphasizes adherence to design principles and best practices to avoid code duplication and enhance maintainability.

1. Code OptimizationsRuby128 minutes

2. Huh? What’s that?2

3. Why would I want to do that?MoneyResourcesHardwarePeople (Developers)TimeSpeed of operationDeveloper takes to figure out what’s going onKarmaNo one wants to write bad code!3

4. 4Ruby

5. Interpolation over Concatenationputs "This string embeds #{a} and #{b} through interpolation"# => fasterputs "This string concatenates "<< a <<" and "<< b # => slowerputs "This string concatenates “+ a +" and "+ b # => slower5

6. Destructive Operations!hash = {}hash =hash.merge({1=>2}) # duplicates the original hashhash.merge!({1=>2}) # equivalent to previous line, and fasterstr="string to gsub"str=str.gsub(/to/, 'copy') # duplicate string and reassigns itstr.gsub!(/to/, 'copy') # same effect, but no object duplication6

7. Benchmark everythingrequire 'benchmark'n =100000Benchmark.bm do |x| x.report('copy') { n.timesdo ; h = {}; h =h.merge({1=>2}); end } x.report('no copy') { n.timesdo ; h = {}; h.merge!({1=>2}); end }end# user system total real# copy 0.460000 0.180000 0.640000 (0.640692)# no copy 0.340000 0.120000 0.460000 (0.463339)7

8. Symbols whenever possible'foo'.object_id# => 23233310'foo'.object_id# => 23228920:foo.object_id# => 239298:foo.object_id# => 2392988

9. Array joins[1, 2, 3] * 3# => [1, 2, 3, 1, 2, 3, 1, 2, 3][1, 2, 3] * '3'# => "13233" %w{thisisatest} * ", "# => "this, is, a, test" h = { :name=>"Fred", :age=>77 }h.map { |i| i * "=" } * "\n"# => "age=77\nname=Fred"9

10. Everything is an object!defadd(adder, addee) adder +addeeend add(3,5) # => 8classFixnumdefadd(num)self+ numendend3.add(5)# => 810

11. Use ranges instead of complex comparisons for numbers# No more if x > 1000 && x < 2000 nonsense. Instead:year =1972puts case yearwhen1970..1979:"Seventies"when1980..1989:"Eighties"when1990..1999:"Nineties"end11

12. Ruby logicdefis_odd(x) if x % 2==0returnfalseelsereturntrueendenddefis_odd(x) x % 2==0?false:trueenddefis_odd(x) x % 2!=0end12classFixnumdef odd?self % 2!=0endend2.odd? # => false

13. Enumerate single object# [*items] converts a single object into an array. And if the object is an array, keeps it as it is.[*items].each do |item|# ...end13

14. 14Rails

15. CachingPage CachingFragment CachingAction CachingCaching into Local / Instance Variable15# Makes a database query only if @current_user is nildefcurrent_user@current_user||=User.find(session[:user_id])end

16. Don’t limit yourself to ActiveRecordUse performance boosting database features like: Stored proceduresFunctionsX-query16

17. Finders are great but be carefulRetrieve only the information that you need. Don’t kill your database with too many queries. Use eager loading.Avoid dynamic finders like MyModel.find_by_*.Need an optimized query? Run MyModel.find_by_sql.17#This will generates only one query,# rather than Post.count + 1 queriesfor post inPost.find(:all, :include=> [ :author, :comments ])# Do something with postend

18. Control your controllersDon’t let them become the God classes.Lesser instance variables.Slimmer the better.Appropriate code in appropriate controller.18

19. 19And of course!

20. 20Obey design principles.Always code in context (Objects). It is the best way to model your solution.Avoid “Quick and dirty”.Understand that no good can ever come out of duplication. Be it code, design, data and most importantly effort.Simplicity is the key.Enjoy coding!

21. 21Slidesslideshare.net/ihower/rails-best-practicesslideshare.net/ihower/practical-rails2-350619slideshare.net/preston.lee/logical-programming-with-ruby-prologRuby BooksThe Ruby Wayby Hal Edwin Fulton, Guy HurstThe Rails Way by Obie FernandezDesign Patterns in Rubyby Russ OlsenSoftware ConstructionCode Complete 2 by Steve McConnellThe Pragmatic Programmer: From Journeyman to Masterby Andrew Hunt