From: Robert Klemme <bob.news@...>
Date: 2005-05-01T07:54:26+09:00
Subject: Re: Cloning into an object


"George Ogata" <g_ogata@optushome.com.au> schrieb im Newsbeitrag 
news:87zmvfx6u9.fsf@optushome.com.au...
> Eric Mahurin <eric_mahurin@yahoo.com> writes:
>
>> Anybody know how to generically copy (shallow like clone) an
>> object into another object?  It would be nice to handle the
>> case where the objects have a different class, but I would at
>> least like to know how to do it when the classes are the same.
>>
>> Here is an example of what I would like to do:
>>
>> dest = Object.new # or String.new if necessary
>> source = "hello world"
>> destid = dest.id
>>
>> source.clone_into(dest)
>>
>> dest             -> "hello world"
>> dest.id==destid  -> true
>> dest.class       -> String
>
> I hear that evil.rb has Object#become, which will do that with some
> caveats.  Search "Object#become" in the list archives for more info.

If you just want to copy state you can do without evil magic (although not 
working for builtins like String, Array, Fixnum etc.):

class Object
  def set_from(o)
    o.instance_variables.each do |var|
      instance_variable_set( var, o.instance_variable_get( var ) )
    end
    self
  end
end

Kind regards

    robert