class Handler
	attr_accessor :entity
	def initialize(entity)
		@entity = entity
	end
	def self.my_attr(name_symbol,&write_block)
		name_string = name_symbol.to_s
		write_symbol = (name_string + "=").to_sym
		if block_given? then
			write_proc = Proc.new{|value|
			new_value = write_block.call(value)
			@entity.write(new_value)

			#the instance_variable_set method creates a class instance variable
			#I want to create a proper instance variable here
			instance_variable_set(("@" + name_string).to_sym,new_value)}
		else
			write_proc = Proc.new{@entity.write(name_string,value)

			#ditto here
			instance_variable_set(("@" + name_string).to_sym,new_value)}
		end
		read_proc = Proc.new{@entity.read(name_string)}

		define_method(name_symbol,read_proc)
		define_method(write_symbol,write_proc)
	end
end

class MyHandler < Handler
	my_attr(:off_center){|new_off_center|
		if new_off_center != @off_center then

			#I want off_center to be an instance variable, not a class instance variable
			#but the behaviour here isn't working out that way
			@off_center = new_off_center + 180
		else
			@off_center = new_off_center - 90
		end
		}
end