ruby.rb

class YesImAClass
	@how_we_usually_do_it="blah"

	def active_overlay
    	@active_overlay ||= (some_method_to_determine_value(...)) ? 'opton 1' : 'option 2'
  	end

	def self.some_method
		AnotherClass.foo(@active_overlay)
	end
end

# Call YesImAClass.some_method and @active_overlay goes from not set to set
# Call YesImAClass.some_method and @active_overlay is already set