Question

In the visitor pattern, i want the client to only have access to the getters of the elements, while the visitors should have access to getters and setters. How would you implement it?

I don’t want the visitors in the same package as the model (there are a lot of classes already).
I was thinking about introducing IWriteable interface which contains setters and accept methods.
Is there a better way?

Thanks

Answer 1

@Angel O’Sphere:

The package would contains models, visitors and factories all that ~2x (interfaces and impls).
I had some thought about rogue programmer too, that’s why I asked.
Another approach would be:

public class ModelImpl implement IRead {
  @Override
  public Foo getFoo() {...}

  private void setFoo(Foo f) {...}

  public void accept(Visitor v) {
    v.visit(new ModelEditor());
  }

  private class ModelEditor implement IWrite {
    @Override
    public void setFoo(Foo f) {
      ModelImpl.this.setFoo(f);
    }
  }
}

But this approach has many drawbacks and is cumbersome without generative techniques 😮