From: dblack@...
Date: 2002-12-09T13:11:07+09:00
Subject: Re: [YANQ] -yet another (ruby) newbie question -string#concat

Hi --

On Mon, 9 Dec 2002, [iso-8859-1] "Pe�a, Botp" wrote:

> Hi sir Gavin (aka Gavin Sinclair [mailto:gsinclair@soyabean.com.au]):
>
> You remarked last Monday, December 09, 2002 11:31 AM:
> >
> > > I wonder how much existing code such a change will break.
> > After all,
> > > who, in
> > a
> > > published program or library, would use #concat ? :)
> >
> >
> > I meant "... such a change *would* break ...".  I don't
> > expect it to be changed any time soon.
>
> deprecating concat is even fine with me (my opinion only -but if it will be
> changed, why not?). From now on, I'll be using "+" and "=" to achieve same
> effect (and may << soon). Less confusion, less worry, works all the time :-)

<< is good, and has that nice palpable feel of sticking something on
the end of the string.

Beware of +=.  It doesn't achieve the same effect.  You end up with a
different object, which might be a problem, depending what else is
going on.  One potential problem is the oft-mentioned:

  class S < String
    def talk; puts "I consist of #{self}"; end
  end

  s = S.new("hello")
  s.talk                # I consist of hello
  s += " there"
  s.talk                # undefined method!

which happens because the + operation returns a String object, not an
S object.  If you do s << " there" instead, you keep the same object
and it continues to respond to 'talk'.

(See the archives... this is another one on which there's been a lot
of past discussion.)


David

-- 
David Alan Black
home: dblack@candle.superlink.net
work: blackdav@shu.edu
Web:  http://pirate.shu.edu/~blackdav