Cop idea: Enumerable#each + push vs Enumerable#map

[ydakuka]

https://github.com/fastruby/fast-ruby#enumerableeach--push-vs-enumerablemap-code

Describe the solution you'd like

class Test
  ARRAY = (1..100).to_a

  # bad
  def slow
    array = []
    ARRAY.each { |i| array.push i }
    array
  end

  # good
  def fast
    ARRAY.map { |i| i }
  end
end

[ydakuka]

I've benchmarked it (ruby 3.3.0).

ydakuka@yauhenid:~/ruby-docker-app$ docker run ruby-app  
ruby 3.3.0 (2023-12-25 revision 5124f9ac75) [x86_64-linux]
Warming up --------------------------------------
                slow    12.748k i/100ms
                fast    20.212k i/100ms
Calculating -------------------------------------
                slow    135.016k (± 1.1%) i/s -    675.644k in   5.004757s
                fast    203.381k (± 0.9%) i/s -      1.031M in   5.068794s

Comparison:
                fast:   203381.5 i/s
                slow:   135016.1 i/s - 1.51x  slower

[koic]

Due to the case of #384, can you verify the results with the latest Ruby 3.3.0dev? It might be a good idea for fastruby to redo benchmark with the latest Ruby version. It might be better to wait until after the scheduled release of Ruby 3.3 next month, rather than doing it now.

[ydakuka]

It might be better to wait until after the scheduled release of Ruby 3.3 next month, rather than doing it now.

I agree. After the release I'll do the benchmarks.

[ydakuka]

Related: rubocop/rubocop#11878

[ydakuka]

After the release I'll do the benchmarks.

I've updated benchmarks in my repos.