-
The Visitor can visit objects that don't have a common parent class.
-
Although the ConcreteElement nodes may represent unrelated classes, they all should derive from a common Element base.
-
The client instantiates a ConcreteVisitor.
-
The traversal algorithm invokes Element::accept(Visitor) for each node.
-
The ConcreteElement calls Visitor::visit(ConcreteElement).
-
The ConcreteVisitor now uses the ConcreteElement interface to carry out node-specific tasks.