Include Weka::Concerns::Persistent in ClusterEvaluation

Author: paulgoetze

lib/weka/clusterers/cluster_evaluation.rb

@@ -1,12 +1,14 @@
+require 'weka/concerns'
+
 module Weka
   module Clusterers
     java_import 'weka.clusterers.ClusterEvaluation'
 
     class ClusterEvaluation
+      include Concerns::Persistent
+
       alias summary        cluster_results_to_string
       alias clusters_count num_clusters
     end
-
-    Java::WekaClusterers::ClusterEvaluation.__persistent__ = true
   end
 end