From: Albert Wagner <alwagner@...>
Date: 2002-01-10T09:54:10+09:00
Subject: Re: How to override subclass#new

On Wednesday 09 January 2002 06:14 pm, you wrote:
> Albert Wagner <alwagner@tcac.net> writes:
> > I have some code similar to below, which expresses my intent, but is
> > not what is happening.  Who is calling B#initialize?  Do I need a
> > call to super in B#initialise?  I keep getting trash in the b and c
> > passed to B#initialize or error messages saying that there are too
> > many args being passed to B#initialize.  I obviously have a very
> > murky understanding of how to achieve what I want.  Thanks ahead for
> > any advice.
> >
> > 	class A
> > 	    def A.new(a, *args)
> > 	    end
> > 	end
> >
> > 	class B < A
> > 	    def B.new(a, b, c)
> > 	        x = 1
> > 	        y = 2
> > 	        z = 3
> > 	        <more>
> > 	        super(a, x, y, z, <more>)
> > 	    end
> > 	    def initialize(a, b, c)
> > 	        @a = a
> > 	        @b = b
> > 	        @c = c
> > 	    end
> > 	end
> >
> > 	B.new(a,b,c)	#<==preferred method of creating a B instance
>
> I am not actually sure what you want, since the only way you show it
> is with code that does not work.  ;-) But in Ruby, you usually do not
> override a class' new method.  Instead just override initialize and
> call super within initialize.

Thank you for the reply, Matt.  I am aware of what is usual in Ruby.  
However, my reasons for doing it are, I think, justified.  Note that I am not 
overriding A#new, but actually attempting to subclass A with B and adding 
behaviour to A#new through B#new.  A#new is left intact to be executed by 
super in B#new.  My problem is that I expected the args a,b and c to be 
passed from B#new to B#initialize, and they are not.  What changes should I 
make in B to have a,b, and c given to B#initialize?  

-- 
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