Circular dependencies of declarations

Question

I am trying to implement example of visitor pattern, but I have trouble with circular dependecies of declarations of classes. When I do forward declaration of class Visitor,

Answer 1

class Visitor; 

class England : public Land {
  public:
    void accept(const Visitor *v); // Only declaration
};


// Define Visitor
class Visitor {
  //...
};

// Now implementation
void England::accept(const Visitor *v) {
      v->visit(this);
}