If I may nitpick, the call to children’s accept methods should be in the visitor, not the parent. Imagine you’re writing an XMLGeneratorVisiter. The visit method for the parent would print <parent>, call child accepts, and then print </parent>. If you do it the way it is done here you lose the control on when the children are visited.
Also, the point of the visitor pattern is not just pattern matching/polymorphism. Of course you could do it with polymorphism or conditionals or whatever. But the visitor pattern reduces coupling and increases cohesion. So you get a more maintainable, testable code base. Pattern matching with a candied switch doesn’t give you that.
Also, the point of the visitor pattern is not just pattern matching/polymorphism. Of course you could do it with polymorphism or conditionals or whatever. But the visitor pattern reduces coupling and increases cohesion. So you get a more maintainable, testable code base. Pattern matching with a candied switch doesn’t give you that.