From: torehalv@... (Tore Halvorsen)
Date: 2004-09-17T22:44:46+09:00
Subject: Re: Automatic class conversion / function overloading

Brian Candler wrote:
[...]
>Essentially it's what you've written. However, you'll find that in
>more cases than you expect you don't actually do it. As long as the
>objects passed in respond to the same methods, you can just invoke
>them without caring what the class is; there is no need for them to
>be inherited from some common superclass as would be the case in C++.
[...]

Thanks for helpfull info, but still...

I agree, but when trying to make a class for rational numbers, I
wanted to be able to multiply both rational and fixnums to it.

class Rational
  attr_reader :u, :d #up, down
  def *(other)
    Rational.new(self.u * other.u, self.d * other.d)
  end
end

This obviously doesn't automatically work when passing a Fixnum as the
argument. The C++ way is to create an automatic converter - or
function overload. So the ruby way here would be:

class Rational
  attr_reader :u, :d
  def *(o)
    case other
      when Rational
        other = o
      when Fixnum
        other = Rational.new(o, 1)
    end
    Rational.new(self.u * other.u, self.d * other.d)
  end
end

?


I need a ruby-idioms book :)

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<demo> 2004 Tore Halvorsen || Cell: +052 0553034554          \(o/