From: Todd Benson <caduceass@...>
Date: 2007-11-07T09:12:29+09:00
Subject: Re: dragons and factorials (keyboard input)

On 11/3/07, Thufir <hawat.thufir@gmail.com> wrote:

> ps:  I'm thinking about class, inheritance and so forth.  I'm going to
> review another thread where I was asking about the ruby equivalent to
> "static class methods" for, specifically, the factorial which I want
> ensure cannot be instantiated.  I know it's an object, because
> everything's an object in Ruby, but have to think about that one.

You want to avoid method's being instantiated per object?  You can
attach the method directly to a class...

class C
  def self.fact
    puts "factorial goes here"
  end
end
C.fact

...or to a module...

module M
  def fact
    puts "factorial goes here"
  end
end
include M
foo

...or to a module while preserving namespace...

module M
  def self.fact
    puts "factorial goes here"
  end
end
M::foo

For factorial, I like the Rubyish...

def fact n
  (1..n).inject { |fact, i| fact * i }
end

...unless there is some performance thing I'm not aware of (or I'm
answering the wrong question).

Todd