From: "David A. Black" <dblack@...>
Date: 2005-11-17T11:15:06+09:00
Subject: Re: Proposed RCR: Object#replace

Hi --

On Thu, 17 Nov 2005, Austin Ziegler wrote:

> On 11/16/05, Eric Mahurin <eric.mahurin@gmail.com> wrote:
>> On 11/16/05, Austin Ziegler <halostatue@gmail.com> wrote:
>>> This is, by the way, exactly what:
>>>   a = {}
>>>   b = []
>>>   b.replace a

Did you mean b = {} ?

> I am suggesting that we implement the same sort of behaviour that we see
> in Hash#replace.
>
>> But, it still doesn't seem very encapsulated because it is using
>> instance_variable_get on other.
>
> It's the best way to do it. It's not perfect, actually, because it's
> only getting instance variables that are currently in self. It would
> need to possibly be a bit more robust (pure pseudocode here):
>
>  class Object
>    def replace(other)
>      # check to make sure that we claim to be the same thing
>      # copy all instance variables from other
>      # delete instance variables in self that aren't in other
>      # return self
>    end
>  end

I'm still totally not understanding what copying instance variables
has to do with Hash/String/Array#replace operations.

   a = {}
   b = {}
   a.instance_eval { @x = 1 }
   b.replace(a)
   b.instance_eval { p @x }     # nil

Other than the big umbrella category of "having to do with state",
what's the connection?


David

-- 
David A. Black
dblack@wobblini.net