On Sun, Nov 8, 2009 at 12:20 PM, Seebs <usenet-nospam@[...].net>  wrote:

>  I don't think that gives the right semantics in many cases.  It's also
>  not clear that rebinding works:
> 
>         array_example.length++
> 
>  What should this do?
> 

Well, this is a very interesting question, as I discovered something about
Ruby I didn't know from this...

Say we have:

class Foo
  attr_reader :bar

  def initialize
    @bar = 0
  end
end

f = Foo.new
f.bar += 1

What do you think the value of a subsequent call to f.bar will be?

I was surprised to discover that it indeed 1.  Somehow += is mutating the
ivar through a supposed "attr_reader" even though there is no corresponding
bar= method.  In that case += appears to be frobbing the ivar directly.

Very strange.  Even worse:

class Foo
  def initialize
    @bar = 0
  end

  def bar
    @bar + 1
  end
end

f = Foo.new
f.bar += 1

Now what do you think the value of a subsequent call to f.bar will be?

Indeed, it would be 3!

I cannot begin to answer this question because Ruby is doing strange and
unexpected things here, at least from my perspective...

-- 
Tony Arcieri
Medioh/Nagravision