From: Austin Ziegler <austin@...>
Date: 2004-02-26T01:05:44+09:00
Subject: Re: Operators +, += and = in Ruby 2

On Thu, 26 Feb 2004 00:29:46 +0900, Simon Strandgaard wrote:
> On Wed, 25 Feb 2004 16:12:16 +0100, Robert Klemme wrote: [snip]
>> What do others think? Did I overlook something?
> It would be really nice to be able to overload '+=', so that #close can
> be invoked correct.

> server> expand -t2 a.rb
> class A
>   @@count = 0
>
>   def initialize(value=nil)
>     @value = value || 0
>     @@count += 1
>   end
>
>   attr_reader :value
>
>   def close
>     @@count -= 1
>   end
>
>   def A.count
>     @@count
>   end
>
>   def +(value)
>     A.new(@value + value)
>   end
> end

I don't see the problem here.

  p A.count   # => 0
  a = A.new
  p A.count   # => 1
  a += 5
  p A.count   # => 2
  a.close
  p A.count   # => 1

It's doing exactly what you told it to do here. I'm presuming that
you want to do:

  def +=(value)
    @value += value
  end

Ultimately, what you're doing with + in this case is trying to do a
#become operation, which Matz has -- at least as far as I can see --
said he won't support.

-austin
--
austin ziegler  * austin@halostatue.ca * Toronto, ON, Canada
software designer * pragmatic programmer * 2004.02.25
                    * 11.00.12