From: William Djaja Tjokroaminata <billtj@...>
Date: 2002-10-24T01:00:07+09:00
Subject: Re: Things That Newcomers to Ruby Should Know (10/16/02)

Hi,

As already been pointed out, this is because in Ruby when a variable is
assigned to another variable, the new variable simply refers to the same
object that the old variable refers to:

    a = AnObject.new
    b = a    # b really refers to the same, identical AnObject as a

Therefore, if '+=' means 'append()', then what you will have is

    b += anotherObj    # a will also be a = a.append(anotherObj)

The only safe/natural way of having '+=' to mean 'append()' is by changing
the semantic in Ruby by having the variable assignment operator to invoke
some copy method:

    # Not a Ruby code
    a = AnObject.new
    b = a    # b = a.copy()
    b += anotherObj    # b = b.append(anotherObj), a unchanged

But Ruby does not work that way; you have to use C++ if that is really the
intention.

Regards,

Bill
=========================================================================
"Mills Thomas (app1tam)" <app1tam@ups.com> wrote:
> But why does it really, REALLY mean that?  Was there a reason for doing
> this?  Is it non-trivial to have '+=' mean 'append()'?

> Drew

>> -----Original Message-----
>> From: Hal E. Fulton [mailto:hal9000@hypermetrics.com] 
>> Sent: Monday, October 21, 2002 11:18 PM
>> To: ruby-talk@ruby-lang.org
>> Subject: Re: Things That Newcomers to Ruby Should Know (10/16/02)
>> 
>> 
>> It's a feature. :) The notation a+=b really, REALLY 
>> means a = a + b. There is a + operator, but never a
>> += operator, in Ruby (or any other assignment).
>> 
>> Hal
>> 
>>