From: William Djaja Tjokroaminata <billtj@...>
Date: 2002-10-22T22:16:50+09:00
Subject: Re: Things That Newcomers to Ruby Should Know (10/16/02)

Hi Ian,

Based on previous responses, I think a standard example answer to your
question is something like this:

    a = 'aString'
    c = a
    a += ' modified using = +'
    puts c    # -> "aString"

    a = 'aString'
    c = a
    a << ' modified using <<'
    puts c    # -> "aString modified using <<"

Because in Ruby the "=" operator only copies the reference (but not the
object), based on the above example, probably you can tell which is more
natural: for the "a += b" to behave like "a = a + b" or to behave like "a
<< b".

If you know C++, then you know that Ruby has made a particular
choice: Ruby does not overload the assignment operator and Ruby does not
treat the "+=" operator as independent from the corresponding
"=" operator.  Although there are always exceptions, I think so far Ruby's
philosophy in this regard is the most natural.

Furthermore, Ruby still gives you a choice for a String as in the example
above.  If your intention is to create a new object (as not to affect c),
you want to use "+="; if your intention is really to modify the object
referred to by a, you want to use "<<" (but be careful that other
variables such as c are also affected).

Regards,

Bill
==========================================================================
Ian Macdonald <ian@caliban.org> wrote:
> I understand that, but since 'a' already exists prior to assigning a + b
> to it, why does it need to be recreated? Where strings are concerned,
> I don't see why this would be any different to 'a << b'.