From: "David A. Black" <dblack@...>
Date: 2005-01-26T11:10:19+09:00
Subject: Re: attr

Hi --

On Wed, 26 Jan 2005, Trans wrote:

>> Oh, and I think that the :x! feature is quite useless. This is
>> an extremely rare special case and I think it's more obvious
>> if written out. Or did you find lots of use cases for it?
>
> No. The only thing that comes to mind is in combination with a casting.
> Somthing like:
>
> |  attr :a! => :upcase
>
> which creates
>
> |  def a!(x)
> |    @a.replace(x.upcase)
> |  end

But think of that from the point of view of someone using the class,
and writing code in a different file.  What you'd see is just this
(using 'text' as the accessor):

   require 'some_file'

   obj = A.new
   obj.text = "Hi there."
   obj.text!
   puts obj.text               # "HI THERE."

which is awfully obscure.  In essence, there's a verb missing; it's
like doing:

   some_string!

instead of

   some_string.upcase!

Also, !-methods don't have any special correspondence to the 'replace'
operation.  All the ! means is that the operation is dangerous (I
think that's the adjective Matz has used) -- which often means it
changes the receiver, but doesn't have to, and it could be a change
that isn't a replace operation.


David

-- 
David A. Black
dblack@wobblini.net