From: Robert Dober <robert.dober@...>
Date: 2007-08-24T20:48:54+09:00
Subject: Re: something I just found out, am sharing (:newbish)

On 8/24/07, David A. Black <dblack@rubypal.com> wrote:
> Hi --
>
> On Fri, 24 Aug 2007, Robert Dober wrote:
>
> > On 8/24/07, David A. Black <dblack@rubypal.com> wrote:
> >> Hi --
> >
> >>
> >> Don't worry -- there's no Academie Anglaise :-)
> > I am not French, only my wife is;), but it is a funny remark.
> >>
> >>> But seriously there is just no need to pay the cost of the
> >>> construction of another String / Array.
> >>> Performance difference is already enormous for moderately long strings :
> >>
> >> It depends, though; sometimes you might want a copy, sometimes you
> >> might definitely not. So the + vs. << decision may not be premature,
> >> and the right decision may not even be the optimizing one :-)
> > Hmm David when one does
> > a += b
> > the copy is thrown away and you have the same semantics (save some
> > implicit calls to to_s) as for
> > a << b
>
> They're not interchangeable, though:
>
> a = "Hello"
> b = " there"
> c = a
>
> a += b
> puts a        # Hello there
> puts c        # Hello
>
> a = "Hello"
> c = a
> a << b
> puts a        # Hello there
> puts c        # Hello there
That is indeed an important - probably the most important - point to
make, I believe that people are not always aware that a+=b is a = a +
b.

I have to admit that I assumed that OP wanted the a << b behavior, but
maybe he did not, that was quite a bad performance of mine...
Robert
>
>
> David
>
> --
> * Books:
>    RAILS ROUTING (new! http://www.awprofessional.com/title/0321509242)
>    RUBY FOR RAILS (http://www.manning.com/black)
> * Ruby/Rails training
>      & consulting:  Ruby Power and Light, LLC (http://www.rubypal.com)
>
>


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