From: Joel VanderWerf <vjoel@...>
Date: 2005-06-26T05:10:01+09:00
Subject: Re: DSL question

Joe Van Dyk wrote:
> Hi,
> 
> require 'traits'
> $applications = {}
> 
> class Application
>   has %w{ application_id title executable options}
> end
> 
> def application(application_id, &block)
>   a = Application.new
>   ###### What goes here?   #############
>   $applications[application_id] = a
> end
> 
> application :joe_app do
>   title       "Joe's Application"
>   executable  "My executable"
>   options     "my options"
> end
> 
> application :another_app do
>   title       "Another App"
>   executable  "another exec"
>   options     "the options"
> end
> 
> 
> It should be pretty apparent to what I'm trying to do.  Any ideas? 
> Can I restructure this better somehow?

instance_eval can help:

class Application
   def title(*args)
     case args.size
     when 1
       @title = args[0]
     when 0
       @title
     end
   end

   def initialize(&block)
     instance_eval(&block)
   end
end

a = Application.new do
   title "Foo"
end

puts a.title   # ==> Foo