From: Robert Klemme <bob.news@...>
Date: 2005-01-26T01:35:49+09:00
Subject: Re: Injecting methods from one class into another.


"Robert Klemme" <bob.news@gmx.net> schrieb im Newsbeitrag
news:35nafhF4of2saU1@individual.net...
>
> "George Moschovitis" <george.moschovitis@gmail.com> schrieb im
Newsbeitrag
> news:1106667522.708436.185960@z14g2000cwz.googlegroups.com...
> > > Object methods do not work in vacuum, they usually use instance
> > > variables to reffer to the object's state, possibly changing it
> > > (remember encapsulation ;-)?). How would you expect your
> > > inject_method() deal with it?
> >
> > I thought Ruby promotes 'duck typing'.
> >
> > I would like to inject specific methods between specific classes. The
> > destination class has all the instance variables needed to succesfully
> > execute the method.
>
> And what about other methods that are used by a method?  I think it's
not
> generally possible to move methods around.
>
> But maybe this trick helps:

Should've read

class Object
  def cast(target_class)
    copy = case target_class
      when Class; target_class.allocate
      when Module; dup.extend(target_class)
      else target_class.class.allocate
    end

    instance_variables.each do |var|
      copy.instance_variable_set(var, instance_variable_get(var))
    end

    copy
  end
end

> Then you can create a tmp copy of an instance with all instance
variables
> copied but a different class.  So you can do
> foo.cast(Bar).bar_method_to_be_called().
>
> Cheers
>
>     robert
>