From: Gavin Sinclair <gsinclair@...>
Date: 2004-10-06T10:51:39+09:00
Subject: Re: A ruby course

On Wednesday, October 6, 2004, 5:18:17 AM, Brian wrote:

> Edgardo Hames wrote:
>> On Wed, 6 Oct 2004 02:24:12 +0900, Brian Schr�der
>> <ruby@brian-schroeder.de> wrote:
>> 
>>>Anybody has an idea for an exercise on extending existing classes. So
>>>far the only thing I have come up with is:
>>>
>> 
>> 
>> Taken from the Design Patterns book, Decorator pattern:
>> 
>> "Attach additional responsibilities to an object dynamically.
>> Decorators provide a flexible alternative to subclassing for extending
>> functionality."
>> 
>> You could extend Integer with a fibonacci method, so that you can
>> write something like:
>> 
>> puts 0.fibonacci       > 0
>> puts 1.fibonacci       > 1
>> puts 5.fibonacci       > 5
> Should be 12, shouldn't it?
>> 
>> My 2 cents.
>> Ed
>> 

> I'm sorry, but this was exactly the example I gave. It seems we have a
> similar mindset ;)

Maybe extend this, then:

  module InlineMath
    def fib; ...; end
    def fac; ...; end
    def sin; ...; end
    def cos; ...; end
    def tan; ...; end
  end

  class Numeric
    include InlineMath
  end

Students have to implement those methods, and try it out with real
numbers.  Caveat: what about 3.5.fib and 3.5.fac?  Do the
trigonometric methods assume degress or radians?

Gavin