package org.apidesign.sidemeanings;

 // BEGIN: sidemeanings.Mixed.Clean

 public final class NonMixed {

     private int counter;

     private int sum;

     private final Provider impl;

     private NonMixed(Provider impl) {

         this.impl = impl;

     }

     public static NonMixed create(Provider impl) {

         NonMixed api = new NonMixed(impl);

         Callback callback = new Callback(api);

         impl.initialize(callback);

         return api;

     }

     public final int apiForClients() {

         int subclass = impl.toBeImplementedBySubclass();

         sum += subclass;

         return sum / counter;

     }

     public interface Provider {

         public void initialize(Callback c);

         public int toBeImplementedBySubclass();

     }

     public static final class Callback {

         NonMixed api;

         Callback(NonMixed api) {

             this.api = api;

         }

         public final void toBeCalledBySubclass() {

             api.counter++;

         }

     }

 }

 // END: sidemeanings.Mixed.Clean