From: Trans <transfire@...>
Date: 2007-01-03T12:43:20+09:00
Subject: Re: Mini-RCR: Extra Argument for Array#join


Ryan Davis wrote:
> On Jan 1, 2007, at 8:40 AM, Trans wrote:
>
> > I wonder how this would fair.
> >
> >   class Array
> >     alias :old_join :join
> >     def join( sep=$,, last_sep=nil )
> >       s = old_join(sep)
> >       if last_sep
> >         rsep = Regexp.escape(sep.to_s)
> >         rlast = Regexp.escape(last.to_s)
> >         s.sub!(/#{rsep}#{rlast}$/,"#{last_sep}#{last}")
> >       end
> >       return s
> >     end
> >   end
> >
> > Sorry, the bencmark script wasn't posted and I didn't feel like
> > recreating it.
>
> % ./blah.rb 1_000_000
> # of iterations = 1000000
>                            user     system      total        real
> null_time             0.140000   0.000000   0.140000 (  0.139480)
> ryan                 19.760000   0.020000  19.780000 ( 19.810269)
> trans                21.290000   0.040000  21.330000 ( 21.398592)
> Loaded suite ./blah
> Started
> ....
> Finished in 0.001109 seconds.
>
> 4 tests, 24 assertions, 0 failures, 0 errors

Eek. That was worse then I thought it would be. Thanks for showing me
though, Ryan.

Of course now that I'm looking at it again I'm wondering how we missed:

  class Array
    def join( sep=$,, last_sep=nil )
      return old_join(sep) unless last_sep
      [slice(0...-1).old_join(sep), last].old_join(last_sep)
    end
  end

That must to be faster.

T.