From: "Simon Kröger" <SimonKroeger@...>
Date: 2006-06-22T05:50:39+09:00
Subject: Re: The difference between s=s+”a” ans s<< ”a”

Robert Dober wrote:
> On 6/21/06, Alan Moen <mapsetah2000-maillist5@yahoo.ca> wrote:
>>
>> Hi,
>>
>> I wonder what is the difference between s=s+"a" ans s<< "a"?
> 
> 
> s = s + "a"
> (1) compute a new String object "s" + a
> (2) set s as a reference to the newly created object
> 
> s<<"a"
> 
> (1) append "a" to the String object s refers to.
> 
> The latter is much faster and should be prefered when possible (it will not
> be possible if s is frozen e.g.)

I think
  s = s + "a" #
or
  s += "a"

should be the norm as long as you do not know that using it will cause
you problems (really only performance problems come to my mind)

Have a look at this:
--------------------------------------
def greet_matz greeting
  greeting << ' matz!'
  puts greeting
end

def greet_nobu greeting
  greeting << ' nobu!'
  puts greeting
end

hello = 'hello'
greet_matz hello
greet_nobu hello
--------------------------------------
#=> hello matz!
#=> hello matz! nobu!

you will get what you expect if you use +=

cheers

Simon