What is the visitor pattern in C++?

Can you explain the visitor pattern in C++?

Sure! The visitor pattern is a design pattern that allows you to separate an algorithm from the object structure on which it operates.

How does it work in practice?

In practice, you create a visitor interface with visit methods for each concrete element class. Each element class implements an accept method that takes a visitor as an argument.

What are the benefits of using the visitor pattern?

The main benefits include adding new operations without modifying existing classes and promoting the single responsibility principle.

Can you give me a code example?

Certainly! Here's a simple example:

class Element {
public:
    virtual void accept(Visitor &v) = 0;
};

class ConcreteElementA : public Element {
public:
    void accept(Visitor &v) override {
        v.visit(*this);
    }
};

class Visitor {
public:
    virtual void visit(ConcreteElementA &element) = 0;
};