cattr-bench.rb

require 'active_support/all'
require 'benchmark/ips'

class Module
  def fake_cattr_accessor(sym)
    private_getter = :"_#{sym}"
    private_setter = :"_#{sym}="
    singleton_class.attr_accessor(private_getter)
    singleton_class.send(:private, private_getter, private_setter)

    owner = self
    singleton_class.define_method(sym) { owner.send(private_getter) }
    singleton_class.define_method(:"#{sym}=") { |a| owner.send(private_setter, a) }
  end
end

class Foo
  cattr_accessor :cattr
  fake_cattr_accessor :fake
end

Foo.cattr = Foo.fake = 42

class Bar < Foo
end

raise "Implementation error" unless Bar.cattr == Bar.fake

5.times do
  puts "== #{Foo.ancestors.size} ancestors =="
  Benchmark.ips do |x|
    x.report('cattr') { Bar.cattr }
    x.report('fake') { Bar.fake }
    x.compare!
  end
  5.times { Foo.include(Module.new) }
end

ruby-2.7.txt

== 7 ancestors ==
Warming up --------------------------------------
               cattr     1.110M i/100ms
                fake   795.780k i/100ms
Calculating -------------------------------------
               cattr     11.123M (± 0.6%) i/s -     56.627M in   5.091436s
                fake      7.978M (± 0.7%) i/s -     40.585M in   5.087327s

Comparison:
               cattr: 11122521.5 i/s
                fake:  7978023.5 i/s - 1.39x  (± 0.00) slower

== 12 ancestors ==
Warming up --------------------------------------
               cattr   875.986k i/100ms
                fake   797.623k i/100ms
Calculating -------------------------------------
               cattr      8.768M (± 0.7%) i/s -     44.675M in   5.095467s
                fake      7.967M (± 0.8%) i/s -     39.881M in   5.006234s

Comparison:
               cattr:  8768066.1 i/s
                fake:  7966818.6 i/s - 1.10x  (± 0.00) slower

== 17 ancestors ==
Warming up --------------------------------------
               cattr   709.909k i/100ms
                fake   797.053k i/100ms
Calculating -------------------------------------
               cattr      7.146M (± 0.8%) i/s -     36.205M in   5.067162s
                fake      7.958M (± 0.8%) i/s -     39.853M in   5.008240s

Comparison:
                fake:  7957872.6 i/s
               cattr:  7145567.0 i/s - 1.11x  (± 0.00) slower

== 22 ancestors ==
Warming up --------------------------------------
               cattr   573.736k i/100ms
                fake   797.993k i/100ms
Calculating -------------------------------------
               cattr      5.731M (± 0.5%) i/s -     28.687M in   5.006109s
                fake      7.969M (± 0.6%) i/s -     39.900M in   5.006868s

Comparison:
                fake:  7969285.8 i/s
               cattr:  5730523.3 i/s - 1.39x  (± 0.00) slower

== 27 ancestors ==
Warming up --------------------------------------
               cattr   485.756k i/100ms
                fake   791.246k i/100ms
Calculating -------------------------------------
               cattr      4.849M (± 0.5%) i/s -     24.288M in   5.008705s
                fake      7.970M (± 0.5%) i/s -     40.354M in   5.063216s

Comparison:
                fake:  7970114.7 i/s
               cattr:  4849224.3 i/s - 1.64x  (± 0.00) slower

ruby-3.0.txt

== 7 ancestors ==
Warming up --------------------------------------
               cattr     1.039M i/100ms
                fake   712.698k i/100ms
Calculating -------------------------------------
               cattr     10.364M (± 0.7%) i/s -     51.932M in   5.011092s
                fake      7.120M (± 0.8%) i/s -     35.635M in   5.005114s

Comparison:
               cattr: 10364004.2 i/s
                fake:  7120207.6 i/s - 1.46x  (± 0.00) slower

== 12 ancestors ==
Warming up --------------------------------------
               cattr   836.979k i/100ms
                fake   702.612k i/100ms
Calculating -------------------------------------
               cattr      8.362M (± 0.8%) i/s -     41.849M in   5.005256s
                fake      7.018M (± 0.7%) i/s -     35.131M in   5.006255s

Comparison:
               cattr:  8361520.1 i/s
                fake:  7017642.9 i/s - 1.19x  (± 0.00) slower

== 17 ancestors ==
Warming up --------------------------------------
               cattr   690.479k i/100ms
                fake   707.572k i/100ms
Calculating -------------------------------------
               cattr      7.041M (± 0.7%) i/s -     35.214M in   5.001448s
                fake      7.093M (± 0.8%) i/s -     36.086M in   5.088152s

Comparison:
                fake:  7092636.8 i/s
               cattr:  7041212.5 i/s - same-ish: difference falls within error

== 22 ancestors ==
Warming up --------------------------------------
               cattr   580.160k i/100ms
                fake   708.509k i/100ms
Calculating -------------------------------------
               cattr      5.778M (± 1.0%) i/s -     29.008M in   5.020674s
                fake      7.081M (± 0.7%) i/s -     35.425M in   5.003460s

Comparison:
                fake:  7080549.4 i/s
               cattr:  5778287.1 i/s - 1.23x  (± 0.00) slower

== 27 ancestors ==
Warming up --------------------------------------
               cattr   498.150k i/100ms
                fake   710.501k i/100ms
Calculating -------------------------------------
               cattr      4.970M (± 0.5%) i/s -     24.908M in   5.011529s
                fake      7.102M (± 0.8%) i/s -     35.525M in   5.002325s

Comparison:
                fake:  7102201.9 i/s
               cattr:  4970190.2 i/s - 1.43x  (± 0.00) slower

>> require 'active_record'
=> true
>> ActiveRecord::Base.ancestors.size
=> 62