Adapter

Adapter Pattern

Type: Structural

Description

The Adapter pattern converts the interface of a class into another interface that clients expect. It allows classes to work together that couldn't otherwise because of incompatible interfaces.

Structure

Implementation

The example implements the Adapter pattern:

• A RectangleLegacy class with an incompatible interface
• A RectangleShapeAdapter that adapts the legacy rectangle to a new interface
• The adapter translates calls from the client to the adaptee (legacy object)

Sample Code

$rectangle = new RectangleShapeAdapter(new RectangleLegacy());
$result = $rectangle->display($x1=10, $y1=10, $x2=20, $y2=20);
$this->assertTrue($result);

When to Use

• When you want to use an existing class, but its interface doesn't match what you need
• When you want to create a reusable class that cooperates with classes that don't necessarily have compatible interfaces
• When you need to use several existing subclasses but it's impractical to adapt their interface by subclassing each one
• When you need to make components work together that weren't designed to work together
• When you need to integrate components from different libraries or frameworks