From: Christoph Rippel <crippel@...>
Date: 2001-01-26T12:40:04+09:00
Subject: [ruby-talk:9907] Re: 101 Misconceptions About Dynamic Languages


"Reimer Behrends" <behrends@cse.msu.edu> wrote in message
news:slrn96vftq.kgf.behrends@allegro.cse.msu.edu...
...
[..]
Sorry I thing may previous reply was a bit to cryptic
and I misunderstood your design (your Polynomials
have only one variable I believe).  Given this I would
rewrite your design
[ ...]
> class Polynomial < Ring
>
>   def type
>     nil # Formal type, undefined
>   end
>
>   # add the usual operations on polynomials here, dependent
>   # on the result of 'type'.
>
> end
>
> class ComplexPolynomial < Polynomial
>
>   def type
>     Complex
>   end
>
> end
as
class Ring
One  = nil
Zero = nil
def +( r)
end
def -(r)
end
def :-
     Zero - self
end
def *(r)
end
end

class Poly  < Ring
Coeff = Ring
end

Never mind the implementation details. If want more flexibility
you can replace the class constants with class attributes (in
this case probably unnecessary)
def Ring.one
end
def Ring.zero
end
def Poly.coeff
     Ring
end

Note you should stick the arithmetic of Poly into a mixin ( this way
you get more flexibility in terms of representation for example
sparse polynomials come to mind). If you write this like this
all your problems with the generative style should go away IMO ..

[...]
> Reimer Behrends

Christoph