From: Dave Howell <groups.2009a@...>
Date: 2010-06-22T09:04:26+09:00
Subject: Got to be a better way to code class variables....

I'm trying to set up an object with overridable defaults, so it will act like this:

	>>	 s1 = Smee.new
	=> 	#<Smee:0x102007618 @middle=nil, @front=nil, @back=nil>
	>> 	s1.middle = 'hi'
	=> 	"hi"
	>> 	s1
	=> 	#<Smee:0x102007618 @middle="hi", @front=nil, @back=nil>
	>> 	Smee.front = "O"
	=> 	"O"
	>>	 s2 = Smee.new
	=> 	#<Smee:0x101ffdbb8 @middle=nil, @front="O", @back=nil>
	>> 	s1 => #<Smee:0x102007618 @middle="hi", @front="O", @back=nil> 
	>> 	Smee.middle = "utu"
	=>	 "utu"
	>> 	s1.middle
	=> 	"hi"
	>> 	s2.middle
	=> 	"utu"

So I can set the properties of an instance of Smee, but if I don't set them, or if I set them back to nil, then the corresponding values that I set on the class will take their place.

This is the closest thing I've gotten so far and it seems ludicrously clunky.

	class Smee
		attr_writer :front, :middle, :back

		class << self
			attr_accessor :front, :middle, :back
		end
	
		def front
			@front || Smee.front
		end

		def middle
			@middle || Smee.middle
		end

		def back
			@back || Smee.back
		end
	end

I'd like to have other methods that worked the same on the class and the instance, but the only way I can figure out how is to type every single method twice. There has *got* to be some terribly clever ruby-esque way of including instance methods as class methods or vice versa, no?