I'm sure this must be a common problem with the Visitor pattern, so thought I'd see if there is a standard solution.
How can you re-code a tree traversal where the methods are built into the tree classes themselves, say
class Node {
void Traverse(SomeType& t) { ... }
};
into code that uses a visitor. Two solutions that come to mind are either
class Visitor {
stack<SomeType> argumentStack;
void Visit() {
// do work, add new arguments onto stack
// call accept() on child objects
// pop stack
}
};
or adding the arguments to the accept(Visitor&) and visit() methods themselves. But then this is no better than the original traversal built into the classes.
As a further problem, what happens if each of the built in traversal methods take different arguments, or some return values and others don't, or they don't all return the same types?
