From: "David A. Black" <dblack@...>
Date: 2004-08-24T11:03:23+09:00
Subject: Re: *with* block?

Hi --

On Tue, 24 Aug 2004, Zach Dennis wrote:

> I am looking for a structure like:
> 
> my_obj = boxWidget.new
> with my_obj do
>     x = 0
>     y = 10
>     width = 100
>     height = 100
> end
> 
> instead of having to say
> 
> my_obj = boxWidget.new
> my_obj.x = 0
> my_obj.y = 10
> my_obj.width = 100
> my_obj.height = 100
> 
> 
> 
> Can you do this already? If not....anyone support an RCR for it besides me?

Every assignment to a bare identifier (x = 0) is parsed as an
assignment to a local variable.  If you want to call a "="-style
method, you have to give the receiver explicitly.  So I don't think a
"with" keyword would add much to what you can already do with
instance_eval:

  my_obj = BoxWidget.new
  my_obj.instance_eval do
    self.x = 0
    self.y = 0
    ...
  end

which then isn't a whole lot better than my_obj.x = 0 and so on.  

Another thing people sometimes do is:

  my_obj = BoxWidget.new do |bw|
    bw.x = 0
    bw.y = 10
    ...
  end

which can be nice because it packages the initialization with the
creation of the object, but of course it only works if
BoxWidget#initialize yields the new object.


David

-- 
David A. Black
dblack@wobblini.net