From: TAKAHASHI Masayoshi <maki@...>
Date: 2001-04-24T12:45:59+09:00
Subject: [ruby-talk:14132] Re: RCR: getClassFromString method

Hi,

Marko Schulz <in6x059@public.uni-hamburg.de> wrote:
> I would use a factory-method for this:
> 
>   class ToolFactory
> 
>      def ToolFactory.getTool
>        case $PLATFORM
>          when "Unix" then Tool_Unix
>          when "PC"   then Tool_PC
>          else             nil
>        end
>      end
> 
>   end

I like using Hash rather than case-when dispatching.

   class ToolFactory

      @@platform2tool = {
        "Unix" => Tool_Unix,
        "PC" => Tool_PC
      }
 
      def ToolFactory.getTool
        @@platform2tool[$PLATFORM]
      end
 
   end

If you would like to use ruby's native platform information
as [ruby-talk:14126], you could use Regexp as key.

   class ToolFactory

      @@platform2tool = [
         [/^(.*)linux$/, Tool_Linux],
         [/solaris/, Tool_Solaris]
      ]
 
      def ToolFactory.getTool
        @@platform2tool.each{|platform, klass|
          if platform =~ RUBY_PLATFORM
            return klass
          end
        }
        return nil
      end
 
   end


Regards,

TAKAHASHI Masayoshi (maki@inac.co.jp)