From: Sean O'Halpin <sean.ohalpin@...>
Date: 2006-02-07T09:34:27+09:00
Subject: Re: Creating classes only when needed?

On 2/6/06, Paatsch, Bernd <BPaatsch@activevoice.com> wrote:
> Hello,
>
> I am fairly new to ruby and need some help
> I am structuring my code using classes.
> The application I work on requires input data. This data may require all or
> some of the classes I create. Instead of having a section in the main code
> creating all classes I would like to create only those classes that I need
> while reading the data. However I do not know how to do that.

Class names are constants. To get a reference to a class from a name
(String or Symbol):

  klass = Object.const_get(classname)

Here's an example to get you going:

  class Class1
    def run
      puts "You chose class 1"
    end
  end

  class Class2
    def run
      puts "You chose class 2"
    end
  end

  # this roundabout way of defining the class name is to emphasise
  # that you can construct the class name dynamically
  n = "1"
  classname = "Class#{n}"

  klass = Object.const_get(classname)
  obj = klass.new
  obj.run
  #=> You chose class 1"

Regards,

Sean