Inside Enumerable
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A look at the Enumerable module in Ruby. What it is, how it works and what you can do with it.
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Inside Enumerable
- 4. hash = { :a => 1, :b => 2} hash.collect do |key, value| value * 4 end [4,8] [4,8,12] [4,8,12] array = [1,2,3] array.collect do |value| value * 4 end range = 1..3 range.collect do |value| value * 4 end
- 5. hash = { :a => 1, :b => 2} hash.collect do |key, value| value * 4 end array = [1,2,3] array.collect do |value| value * 4 end range = 1..3 range.collect do |value| value * 4 end module Enumerable def collect ... end end
- 7. mixins
- 8. Mixins Cannot be instantiated Can be mixed in
- 10. Enumerable requires each() [1,2,3].collect {|i| i*2} [2,4,6]
- 11. Enumerable.collect class Foo include Enumerable def each yield 1 yield 2 yield 3 end end Foo.new.collect do |num| num * 2 end module Enumerable def collect array = [] each do |a| array << yield (a) end array end end
- 12. Enumerable.collect module Enumerable def collect array = [] each do |a| array << yield (a) end array end end class Foo include Enumerable def each yield 1 yield 2 yield 3 end end Foo.new.collect do |num| num * 2 end
- 13. Enumerable.collect module Enumerable def collect array = [] each do |a| array << yield (a) end array end end class Foo include Enumerable def each yield 1 yield 2 yield 3 end end Foo.new.collect do |num| num * 2 end
- 14. Enumerable.collect class Foo include Enumerable def each yield 1 yield 2 yield 3 end end Foo.new.collect do |num| num * 2 end module Enumerable def collect array = [] each do |a| array << yield (a) end array end end
- 15. Enumerable.collect module Enumerable def collect array = [] each do |a| array << yield (a) end array end end class Foo include Enumerable def each yield 1 yield 2 yield 3 end end Foo.new.collect do |num| num * 2 end
- 16. Enumerable.collect class Foo include Enumerable def each yield 1 yield 2 yield 3 end end Foo.new.collect do |num| num * 2 end module Enumerable def collect array = [] each do |a| array << yield (a) end array end end Result [2,4,6]
- 18. Enumerable methods all?, any?, collect, detect, each_cons, each_slice, each_with_index, entries, enum_cons, enum_slice, enum_with_index, find, find_all, grep, include?, inject, map, max, member?, min, partition, reject, select, sort, sort_by, to_a, to_set, zip
- 19. any? [1,2,3,4].any? {|a| a > 2} Returns true if this block... ...returns true for any of these values
- 20. all? [1,2,3,4].all? {|a| a > 2} Returns true if this block... ...returns true for ALL of these values
- 26. Case equality case myvar when 1..50 # do something when 51 # do something when /^+$/ # do something end Within the range This exact number Matches this regular expression Different kind of equality as a convenience in case statements
- 27. Case equality in grep [1,2,3].grep(1..50) [1,2,3].grep(51) [1,2,3].grep(/^+$/) Within the range This exact number Matches this regular expression