Design Patterns in PHP and Laravel

© Kelt Dockins 2017

Kelt Dockins, Design Patterns in PHP and Laravel, 10.1007/978-1-4842-2451-9_26

26. Visitor

Kelt Dockins¹ 

(1)Dolph, Arkansas, USA

$> git checkout visitor

Intent

Represent an operation to be performed on the elements of an object structure. Visitor lets you define a new operation without changing the classes of the elements on which it operates.¹

Applications

This is probably one of the most complicated GoF patterns I’ve seen. The first time I stared at the UML diagram after a while I said, “hmm, wat ²?” At its basic form, this pattern is all about extracting methods from semi-related or unrelated classes. When you do this, you no longer have to change or revisit (pun intended) the code. After reading more about this pattern I ...