From: Nat Pryce <nat.pryce@...13media.com>
Date: 2001-11-23T01:09:34+09:00
Subject: [ruby-talk:26151] Re: Passing class names to constructors.

Don't pass in a symbol, pass in a reference to the class object you want to
use.  The class object is a Factory.  See
http://www.rubygarden.org/ruby?AbstractFactoryPattern for more detail.

E.g.

class TangledRope
    def initialize( knotclass = Knot )
        mess = Array.new()

        (10*rand()).times do
                mess.push(knotclass.new())
        end
end

Cheers,
            Nat.

________________________________
Dr. Nathaniel Pryce
B13media Ltd.
40-41 Whiskin St, London, EC1R 0BP, UK
http://www.b13media.com

XP Day, London, UK. 15th December 2001. http://xpday.xpdeveloper.com/

----- Original Message -----
From: "Hugh Sasse Staff Elec Eng" <hgs@dmu.ac.uk>
To: "ruby-talk ML" <ruby-talk@ruby-lang.org>
Sent: Thursday, November 22, 2001 3:32 PM
Subject: [ruby-talk:26141] Passing class names to constructors.


> If I want to create a variable number of objects, all of
> subclasses of one class, then how do I do that?
> Eg in my knots example I might want
>
> class TangledRope
>     def initialize(knotclass = :Knot)
>         mess = Array.new()
>         (10*rand()).times do {
>             mess.push(knotclass.something.new())
>         }
> end
>
> so how do I turn the symbol into the class, so I can do things with it?
> I don't like the obvious way: Deliver Us From Eval!  :-)
>
> Hugh
>
>
>
>