From: Robert Klemme <bob.news@...>
Date: 2005-01-26T01:30:50+09:00
Subject: Re: Injecting methods from one class into another.


"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:

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