From: "David A. Black" <dblack@...>
Date: 2003-12-10T20:33:44+09:00
Subject: Re: Request for comments (longish)

Hi --

On Wed, 10 Dec 2003, Luke A. Kanies wrote:

> class Operation
> 	@derivatives = {}
> 	attr_reader :retrieve, :object
> 	attr_writer :retrieve, :fix, :object
> 
> 	# operations will be retrieved from the base class by name
> 	# should i be using symbols here instead of strings?

I don't think it matters, except that it might be a little faster with
symbols if you're doing lots of hash access.  If you just want to give
people the choice, you can canonicalize the object with #to_s or
#intern.

> 	def Operation.[](name)
> 		unless @derivatives.include?(name)
> 			raise "No class Operation::#{name}"
> 		end
> 
> 		return @derivatives[name]
> 	end

This is a place where you could, conceivably, use my favorite
1.8.0-and-greater "trick":

  class Operation
    @derivatives = Hash.new {|k,v| raise "No class Operation::#{v}" }
    # ...
    def Operation.[](name)
      @derivatives[name]
    end

:-)


David

-- 
David A. Black
dblack@wobblini.net