Visitor__

Purpose

The Visitor Pattern lets you outsource operations on objects to other objects. The main reason to do this is to keep a separation of concerns. But classes have to define a contract to allow visitors (the Role::accept method in the example).

The contract is an abstract class but you can have also a clean interface. In that case, each Visitor has to choose itself which method to invoke on the visitor.

UML Diagram

.. image:: uml/uml.png :alt: Alt Visitor UML Diagram :align: center

Code

You can also find this code on GitHub_

RoleVisitor.php

.. literalinclude:: RoleVisitor.php :language: php :linenos:

RecordingVisitor.php

.. literalinclude:: RecordingVisitor.php :language: php :linenos:

Role.php

.. literalinclude:: Role.php :language: php :linenos:

User.php

.. literalinclude:: User.php :language: php :linenos:

Group.php

.. literalinclude:: Group.php :language: php :linenos:

Test

Tests/VisitorTest.php

.. literalinclude:: Tests/VisitorTest.php :language: php :linenos:

.. _GitHub: https://github.com/DesignPatternsPHP/DesignPatternsPHP/tree/main/Behavioral/Visitor .. __: http://en.wikipedia.org/wiki/Visitor_pattern