README

This package provides a visitor pattern implementation.

Visitor Pattern

Visitor is a behavioral design pattern that lets you separate algorithms from the objects on which they operate.

Install

Via Composer

$ composer require thrashzone13/visitor

Usage

Consider having an array of different kinds of shapes

$shapes = [
    new Circle(radius: 10),
    new Rectangle(width: 15, height: 20),
    new Rectangle(width: 10, height: 14),
    new Square(side: 16)
];

Let's say the intention is to calculate their area and sum them up. There can be a visitor which does the calculation regarding the type of the received instance

$visitor = (new Visitor)
    ->add(fn(Circle $circle) => pi() * $circle->getRadius() * $circle->getRadius())
    ->add(fn(Square $square) => $square->getSide() * $square->getSide())
    ->add(fn(Rectangle $rectangle) => $rectangle->getWidth() * $rectangle->getHeight());

Now it's ready to use!

$totalArea = 0;
foreach ($shapes as $shape) {
    $totalArea += $visitor->visit($shape);
}

License

The MIT License (MIT). Please see License File for more information.