defined? vs instance_variable_defined?/const_defined?/etc #325
Description
defined? (besides that is universal and shorter) is 20% faster than other specialized _defined? methods. But, obviously, can be applied only to self/nil receiver.
# frozen_string_literal: true
require "bundler/inline"
gemfile(true) do
source "https://rubygems.org"
git_source(:github) { |repo| "https://github.com/#{repo}.git" }
gem "benchmark-ips"
end
class Foo
def initialize
@value = 1
end
def foo
defined?(@value)
end
def bar
instance_variable_defined?(:@value)
end
end
f = Foo.new
Benchmark.ips do |x|
x.report("defined?") do
f.foo
end
x.report("instance_variable_defined?") do
f.bar
end
x.compare!
endWarming up --------------------------------------
defined? 934.424k i/100ms
instance_variable_defined?
780.344k i/100ms
Calculating -------------------------------------
defined? 9.318M (± 0.5%) i/s - 46.721M in 5.014049s
instance_variable_defined?
7.794M (± 0.3%) i/s - 39.017M in 5.005796s
Comparison:
defined?: 9318309.9 i/s
instance_variable_defined?: 7794499.8 i/s - 1.20x (± 0.00) slower
== disasm: #<ISeq:[email protected]:16 (16,2)-(18,5)> (catch: FALSE)
0000 putnil ( 17)[LiCa]
0001 defined instance-variable, :@value, "instance-variable"
0005 leave ( 18)[Re]
== disasm: #<ISeq:[email protected]:20 (20,2)-(22,5)> (catch: FALSE)
0000 putself ( 21)[LiCa]
0001 putobject :@value
0003 opt_send_without_block <calldata!mid:instance_variable_defined?, argc:1, FCALL|ARGS_SIMPLE>
0005 leave ( 22)[Re]