From: Sean O'Halpin <sean.ohalpin@...>
Date: 2005-10-22T21:36:07+09:00
Subject: Re: Reflection, observ(er|able) instance vars?

On 10/21/05, Hugh Sasse <hgs@dmu.ac.uk> wrote:
> This "delivers us from eval" :-) but does define_method offer
> anything else over the class_eval %{...} approach?  Maybe [only :-)]
> speed?
Yes, but not perhaps what you were expecting (2 files below):

# file 1: compare def vs block method call overhead
require 'benchmark'
include Benchmark

eval %[
def def_method(x)
  x
end
]

Object.send(:define_method, :defined_method) { |y|
  y
}

block_call = proc {|z| z }

BM = 100000
bm(20) {|x|
  x.report("def")             { BM.times { def_method(1) }}
  x.report("define_method")   { BM.times { defined_method(1) }}
  x.report("block_call")      { BM.times { block_call[1] }}
  }
__END__
                          user     system      total        real
def                   0.070000   0.000000   0.070000 (  0.070000)
define_method         0.240000   0.000000   0.240000 (  0.251000)
block_call            0.250000   0.000000   0.250000 (  0.250000)

# file 2: compare cost of eval vs define method

require 'benchmark'
include Benchmark

BM = 100000
bm(20) {|x|
  x.report("eval def")        { BM.times { eval "def def_method(x) x end" }}
  x.report("define_method")   { BM.times { Object.send(:define_method,
:defined_method) { |y| y } }}
  x.report("block_call")      { BM.times { block_call = proc {|z| z } }}
  }
__END__
                          user     system      total        real
eval def              2.744000   0.000000   2.744000 (  2.744000)
define_method         3.585000   0.040000   3.625000 (  3.686000)
block_call            1.191000   0.050000   1.241000 (  1.252000)

Regards,

Sean

(P.S. This is on WinXP SP2 Dell D600 laptop with 1.6GHz Pentium + 1GB RAM)