From: nobu.nokada@...
Date: 2001-12-29T09:20:44+09:00
Subject: [ruby-talk:29605] Re: extending method of class A to support arguments of class B by promoting `self' to class B

At Sat, 29 Dec 2001 07:53:38 +0900,
Tomasz Wegrzanowski <taw@users.sourceforge.net> wrote:
> Class Real has method `*' that can use argument Real.
> 
> I make class Complex. Class Complex also
> has function `*' which can take either Real or Complex argument.
> Object Complex can be created from Real by Complex.new(real_object).
> 
> I want to tell Ruby, that when Real object is called with Complex
> argument it should be promoted to Complex and then appropriate
> Complex method be called.

Define Complex#coerce if you mean only Numeric classes.  See
lib/complex.rb for complete codes.

  class Complex
    def coerce(real_object)
      [Complex.new(real_object), self]
    end
  end


Otherwise, if you mean generic classes, there's no such
framework now.


Nobu Nakada