Mastering PHP Design Patterns by Unknown

Author:Unknown
Language: eng
Format: mobi, epub
Publisher: Packt Publishing

By using the Decorator design pattern, we are able to ensure that functionality is divided between classes with unique areas of concern, thus adhering to the Single Responsibility Principle.

Let's start off by declaring our Book interface. This is what we expect our Books to be able to produce:

<?php interface Book { public function __construct(string $title, string $author, string $contents); public function getTitle(): string; public function getAuthor(): string; public function getContents(): string; }

Then we can declare our EBook.php class. This is the class we will be decorating with our PrintBook class:

<?php class EBook implements Book { public $title; public $author; public $contents; public function __construct(string $title, string $author, string $contents) { $this->title = $title; $this->author = $author; $this->contents = $contents; } public function getTitle(): string { return $this->contents; } public function getAuthor(): string { return $this->author; } public function getContents(): string { return $this->contents; } }

Now we can declare our PrintBook class. This is what we're using to decorate the EBook class:

<?php class PrintBook implements Book { public $eBook; public function __construct(string $title, string $author, string $contents) { $this->eBook = new EBook($title, $author, $contents); } public function getTitle(): string { return $this->eBook->getTitle(); } public function getAuthor(): string { return $this->eBook->getAuthor(); } public function getContents(): string { return $this->eBook->getContents(); } public function getText(): string { $contents = $this->eBook->getTitle() . " by " . $this->eBook->getAuthor(); $contents .= "\n"; $contents .= $this->eBook->getContents(); return $contents; } }

So now let's test all this with our index.php file:

<?php require_once('Book.php'); require_once('EBook.php'); $PHPBook = new EBook("Mastering PHP Design Patterns", "Junade Ali", "Some contents."); require_once('PrintBook.php'); $PHPBook = new PrintBook("Mastering PHP Design Patterns", "Junade Ali", "Some contents."); echo $PHPBook->getText();

The output looks like this:

Some contents. by Junade Ali Some contents.

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