From: Alan Chen <alan@...>
Date: 2002-02-20T04:28:15+09:00
Subject: Re: advice on dispatch tables

On Wed, Feb 20, 2002 at 04:06:11AM +0900, Matt Armstrong wrote:
> Mark Probert <probertm@nortelnetworks.com> writes:
> 
> > I am playing around with using a dispatch table rather
> > than a huge case statement.  I end up with code that
> > looks something like this:
> >
> >
> >   class Bob
> >
> >      def initialize
> >          @dispatch = Hash.new
> >          @dispatch['a'] = 'do_a'
> >          @dispatch['b'] = 'do_b'
> 
> I'd use symbols instead of strings here:
> 
>           @dispatch['a'] = :do_a
>           @dispatch['b'] = :do_b

Or you could use method objects which should run a bit faster.
           @dispatch['a'] = self.method( :do_a )
           @dispatch['b'] = self.method( :do_b )


> >      end
> >
> >      def do_a
> >          puts "--> this is an a"
> >      end
> >
> >      def do_b
> >          puts "--> this is an b"
> >      end
> >
> >      def dispatch(ref=nil)
> >          if @dispatch[ref]
> >              eval @dispatch[ref]
	         @dispatch[ref].call
> >          else
> >              puts "--> unknown ref (#{ref})"
> >          end
> >      end
> >    end


-- 
Alan Chen
Digikata LLC
http://digikata.com