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Replace Enumerable#reverse.each with Enumerable#reverse_each #17244

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merged 1 commit into from Oct 13, 2014

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commented Oct 13, 2014

Similar to #17099, Enumerable#reverse allocates an extra array. Enumerable#reverse_each yields each value without allocating an extra array. This is the reason why Enumerable#reverse_each exists. It is also about 17% faster.

Benchmark
require 'benchmark/ips'

ARRAY = (1..100).to_a

def slow
  ARRAY.reverse.each{|x| x}
end

def fast
  ARRAY.reverse_each{|x| x}
end

Benchmark.ips do |x|
  x.report('slow') { slow }
  x.report('fast') { fast }
end
Ruby 2.1.2
slow 156173.2 (±9.2%) i/s - 770040 in 5.009112s
fast 182859.3 (±7.8%) i/s - 914486 in 5.035575s

fxn added a commit that referenced this pull request Oct 13, 2014

Merge pull request #17244 from sferik/reverse_each
Replace Enumerable#reverse.each with Enumerable#reverse_each

@fxn fxn merged commit 85901b4 into rails:master Oct 13, 2014

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