From: Phlip <phlip_cpp@...>
Date: 2001-11-23T05:16:05+09:00
Subject: [ruby-talk:26175] Re: Passing class names to constructors.

Hugh Sasse Staff Elec Eng wrote:

> If I want to create a variable number of objects, all of
> subclasses of one class, then how do I do that?

When I applied the first big Refactor (yippee!) to my Flea project, 
"Replace Monster Switch-Case with Polymorphism," I just typed in code that 
passes the class name as a reference, and then calls 'new' on it. I was 
incompletely aware of the : colon operator at the time, but nothing stopped 
me:

class ActLeft < Action
        # ...
end

# ...

        def _absorbAction act, q = nil
                action = act.new (q)
                @actions << action
                return self
        end


    def left      q = nil;  return _absorbAction (ActLeft     , q);  end
    def longer    q = nil;  return _absorbAction (ActLonger   , q);  end
    def move      q = nil;  return _absorbAction (ActMove     , q);  end

That's all; the reference 'act' links the class 'ActLeft', so 'act.new' 
calls 'ActLeft.new'.

Now what was the problem again? (And why are many of the other 
answers to this question so exotic??)

(BTW I would appreciate design suggestions about flea's object model, now 
that I have a long weekend with lots of carbohydrate highs to work in ;-)

        http://flea.sourceforge.net

-- 
Phlip

http://www.greencheese.org/HatTrick