From: Logan Capaldo <logancapaldo@...>
Date: 2006-09-04T12:32:24+09:00
Subject: Re: Exploring Metaprogramming


On Sep 3, 2006, at 10:39 PM, Michael Gorsuch wrote:

>
> What if I want to build a second method called 'command'?  It  
> should place
> the argument in an array that can be referenced later.  It will  
> need to also
> build an initialize method for my class, but one of them will have  
> to be
> overwritten.
>
> Does anyone have any smart ways to combine or chain these two  
> initialize
> methods together?
>
> I ultimately want to do something like this:
>
> class Dragon < Creature
>   traits :life
>   life 100
>
>   command :fly
>
>   def fly
>     puts "I am flying..."
>   end
>
> end
>
> After an instance is created, it will contain the instance variable
> 'commands', which is an array holding the symbol 'fly'.
>
> Does anyone have any ideas?  In the end, I'd be adding more and  
> more of
> these commands to my DSL.  This is a DSL, right?  ;-)

Sorry I seem to have under estimated what you wanted.

try this instead:

% cat dragon.rb
class Creature
   def self.command(cmd)
     old_initialize = instance_method(:initialize)
     define_method(:initialize) do |*args|
       @commands ||= []
       @commands |= [cmd]
       old_initialize.bind(self).call(*args)
     end
   end

   def commands
     @commands ||= []
   end
end

class Dragon < Creature
   command :fly
   def fly
     puts "I'm flying"
   end

   command :breathe_fire

   def breathe_fire
     puts "I'm breathing fire!"
   end
end

dragon = Dragon.new
p dragon.commands

% ruby dragon.rb
[:breathe_fire, :fly]