Ruby benchmark: !@ivar vs defined? @ivar

gistfile1.rb

#!/usr/bin/env ruby -w
require "benchmark"

TIMES = 10_000_000

class Demo
  def initialize
    @ivar = nil
  end

  def check_not_nil
    !@ivar
  end

  def check_defined
    defined? @ivar
  end
end

demo = Demo.new

Benchmark.bm(30) do |b|
  b.report "!@ivar" do
    TIMES.times do |i|
      demo.check_not_nil
    end
  end

  b.report "defined? @ivar" do
    TIMES.times do |i|
      demo.check_defined
    end
  end
end

__END__
                                    user     system      total        real
!@ivar                          3.330000   0.000000   3.330000 (  3.392318)
defined? @ivar                  5.530000   0.010000   5.540000 (  5.550502)