From: Phrogz <gavin@...>
Date: 2007-03-27T00:30:06+09:00
Subject: Re: Knocking Lines Out Of A Multiline String

On Mar 23, 12:39 pm, "Rick DeNatale" <rick.denat...@gmail.com> wrote:
> str.reject {|s| Regexp.new("/usr/local/lib").match(s)}

Note that the above results in Regexp#new being called for each line
in the string; not very efficient:
  require 'Benchmark'

  s = "foobar"
  N = 1000000

  Benchmark.bmbm{ |x|
    x.report( 'Regexp.new' ){
      N.times{ Regexp.new( "foobar" ) =~ s }
    }
    x.report( 'inline literal' ){
      N.times{ /foobar/ =~ s }
    }
    x.report( 'as variable' ){
      r = /foobar/
      N.times{ r =~ s }
    }
  }

  #=> Rehearsal --------------------------------------------------
  #=> Regexp.new      20.844000   1.875000  22.719000 ( 22.750000)
  #=> inline literal   0.906000   0.000000   0.906000 (  0.906000)
  #=> as variable      1.094000   0.000000   1.094000 (  1.094000)
  #=> ---------------------------------------- total: 24.719000sec
  #=>
  #=>                      user     system      total        real
  #=> Regexp.new      21.234000   1.671000  22.905000 ( 22.922000)
  #=> inline literal   0.891000   0.000000   0.891000 (  0.891000)
  #=> as variable      1.047000   0.000000   1.047000 (  1.047000)



If you just want to avoid having to escape the forward slashes in the
literal, you can use the %r notation for a regexp literal. For
example:
  str.reject{ |s| %r{/usr/local/lib} =~ s }