From: Lars Olsson <lasso@...>
Date: 2010-09-12T22:20:07+09:00
Subject: Re: How to do foo.chomp!.rstrip!.downcase! ?

On 12 Sep, 15:13, Lars Olsson <la...@lassoweb.se> wrote:
> On 10 Sep, 23:11, Jesús Gabriel y Galán <jgabrielyga...@gmail.com>
> wrote:
>
>
>
> > On Fri, Sep 10, 2010 at 8:49 PM, Jason Roelofs <jameskil...@gmail.com> wrote:
> > > On Sep 10, 2010, at 1:29 PM, Jesús Gabriel y Galán wrote:
>
> > >> On Fri, Sep 10, 2010 at 6:26 PM, Jason Roelofs <jameskil...@gmail.com> wrote:
> > >>> On Sep 10, 2010, at 11:28 AM, ara.t.howard wrote:
>
> > >>>>> ...it seems like I should be able todo:
>
> > >>>>>foo.chomp!.rstrip!.downcase!
>
> > >>>> you can.
>
> > >>>> %w( chomp!rstrip!downcase! ).each{|m| foo.send(m)}
>
> > >>>> -a
>
> > >>> So... what's wrong with:
>
> > >>> foo =foo.chomp.rstrip.downcase
>
> > >> Each call creates a copy of the string, and are all discarded along
> > >> with the original except the last one.
>
> > >> Jesus.
>
> > > I don't see any problem there, that's expected. Ruby has a GC, and those will get cleaned up appropriately.
>
> > > The ! versions don't work chained, this version does. You shouldn't be worrying about the cost of creating 3 strings.
>
> > I know, regarding that, I don't see any problem either with
>
> >foo.chomp!
> > foo.rstrip!
> > foo.downcase!
>
> > Robert commented on this already (although his email was lost in some
> > problem with SpamAssassin, but he resent):
>
> > Robert Klemme wrote:
> > > ... which usually is less efficient.  I guess OP had a reason to
> > > use bang versions.
>
> > and I clarified. If it's three strings, no problem. If this is in a
> > loop you might want to reduce garbage. Just pointing out a fact about
> > the non-bang methods.
>
> > Jesus.
>
> Yeah, looking at the source code for ruby 1.9 reveals that
> String.chomp is essentially implemented as String.sup.chomp!, so
> you're absolutely right about the non bang versions creating some
> extra garbage. The same is true about (rstripanddowncaseas well.)
> How this affects the overall performance is really hard to say without
> benchmarking though. But as Robert claimed
>
> foo.chomp!
> foo.rstrip!
> foo.downcase!
>
> is probable the most efficient way.
>
> /lasso

Argh...it was supposed to read "implemented as String.dup.chomp!"

/lasso