From: Ryan Leavengood <leavengood@...>
Date: 2006-01-14T00:05:00+09:00
Subject: Re: Looking up properties and speed

On 1/11/06, Jonathan Leighton <lists@turnipspatch.com> wrote:
> Hi,
>
> In Javascript, if one were to use the same property value twice or more,
> one would store it in a local variable because looking up the property
> slows things down.
>
> Is the situation the same in Ruby?

In almost any language method calls will be slower than directly
accessing a variable. I did a quick benchmark with my "quickbench"
utility (I'll release it one of these days), and here are the results:

-------------------------------------------------------------------------
|                      QuickBench Session Started                       |
|                          3000000 Iterations                           |
-------------------------------------------------------------------------
                                  user     system      total        real
1. test.foo == other_var      2.547000   0.000000   2.547000 (  2.407000)
2. var == other_var           1.688000   0.000000   1.688000 (  1.595000)
-------------------------------------------------------------------------
|                   Fastest was <2. var == other_var>                   |
-------------------------------------------------------------------------

So the method call it about half as fast, which isn't that bad. Here
is the code:

require 'quickbench'

class Test
  attr_reader :foo
  def initialize(foo)
    @foo = foo
  end
end

test = Test.new('something')
val = test.foo
other_val = 'blah'
QuickBench.go(3000000, 25) {}

__END__
test.foo == other_val
val == other_val