PHP Классы - 10

[netcat-na-diary]

Статические методы и свойства

<?php
	class StaticExample {
		static public $aNum = 0;
		
		static public function sayHello() {
			print "Привет!";
		}
	}
	
	echo StaticExample::$aNum."<br>";
	StaticExample::sayHello();
?>

Для обращения к статическим методам внутри класса используется ключевое слово self

<?php
	class StaticExample {
		static public $aNum = 0;
		
		static public function sayHello() {
			self::$aNum++;
			print "Привет! (" . self::$aNum . ")\n";
		}
	}
	
	echo StaticExample::$aNum."<br>";
	StaticExample::sayHello();
?>

Создадим таблицу в БД

CREATE TABLE products (
	id INTEGER NOT NULL PRIMARY KEY AUTO_INCREMENT,
        type TEXT,
        firstname TEXT,
        mainname TEXT,
        title TEXT,
        price FLOAT,
        numpages INT,
        playlength INT,
        discount iNT
);

Статический метод для создания экземпляра объекта из БД

<?php
	class ShopProduct {
		private $title;
		private $producerMainName;
		private $producerFirstName;
		protected $price;
		private $discount = 0;
		private $id = 0;
		
		public function __construct ( $title, $firstName, $mainName, $price )
		{
			$this->title = $title;
			$this->producerMainName = $mainName;
			$this->producerFirstName = $firstName;
			$this->price = $price;
		}
		
		public function getProducerFirstName () {
			return $this->producerFirstName;
		}
		
		public function getProducerMainName () {
			return $this->producerMainName;
		}
		
		public function setDiscount ( $num ) {
			$this->discount = $num;
		}
		
		public function getDiscount() {
			return $this->discount;
		}
		
		public function getTitle() {
			return $this->title;
		}
		
		public function getPrice() {
			return ($this->price - $this->discount);
		}
		
		public function getProducer() {
			return "{$this->producerFirstName} "."{$this->producerMainName}";
		}
		
		public function getSummaryLine() {
			$base = "$this->title ( {$this->producerMainName}, ";
			$base .= "{$this->producerFirstName})";
			return $base;
		}
		
		public function setID ( $id ){
			$this->id = $id;
		}
		
		public static function getInstance ( $id, PDO $pdo ) {
			$stmt = $pdo->prepare("select * from products where id=?");
			$result = $stmt->execute ( array($id) );
			
			$row = $stmt->fetch();
			
			if (empty ($row) ) { return null; }
			
			if ( $row['type'] == 'book' ) {
				$product = new BookProduct($row['title'], 
										   $row['firstname'], 
										   $row['mainname'], 
										   $row['price'], 
										   $row['numpages']
										   );
				}
				else if ( $row['type'] == 'cd' ) {
				$product = new CDProduct ($row['title'], 
										  $row['firstname'], 
										  $row['mainname'], 
										  $row['price'], 
										  $row['playlength']
										  );
				}
				else 
				{
					$product = new ShopProduct ($row['title'], 
												$row['firstname'], 
												$row['mainname'], 
												$row['price']
												);
				}
				
				$product->setID( $row['id'] );
				$product->setDiscount ( $row['discount'] );
				return $product;
			}
		}

	class CDProduct extends ShopProduct {
		private $playLength;
		
		public function __construct ( $title, $firstName, $mainName, $price, $playLength )
		{
			parent::__construct ( $title, $firstName, $mainName, $price );
			$this->playLength = $playLength;
		}
	
		public function getPlayLength() {
			return $this->playLength;
		}
		
		public function getSummaryLine() {
			$base = parent::getSummaryLine();
			$base .= ": Время звучания - {$this->playLength}";
			return $base;
		}
	}
	
	class BookProduct extends ShopProduct {
		private $numPages;
		
		public function __construct ( $title, $firstName, $mainName, $price, $numPages )
		{
			parent::__construct ( $title, $firstName, $mainName, $price );
			$this->numPages = $numPages;
		}
	
		public function getNumberOfPages() {
			return $this->numPages;
		}
		
		public function getSummaryLine() {
			$base = parent::getSummaryLine();
			$base .= ": {$this->numPages} стр.";
			return $base;
		}
		
		public function getPrice() {
			return $this->price();
		}
	}
	
	try {
		$pdo = new PDO('mysql:host=test7;dbname=test7', root, null);
	}
	catch (Exception $e) {
		echo 'Выброшено исключение: ',  $e->getMessage(), "\n";
	}
	
	$pdo->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
	$obj = ShopProduct::getInstance(1, $pdo);
        print_r($obj);
?>

Абстрактные классы

	abstract class ShopProductWriter {
		protected $products = array();
		
		public function addProduct ( ShopProduct $shopProduct )
		{
			$this->products[] = $shopProduct;
		}

		abstract public function write(); 
	}
	
	class XmlProductWriter extends ShopProductWriter {
		public function write() {
			$str = '<?xml version="1.0" encoding="UTF-8"?>' . '\n';
			$str .= '<products>\n';
			foreach	( $this->products as $shopProduct )	{
				$str .= "\t<product title=\"{$shopProduct->getTitle()}\">\n";			}
				$str .= "\t\t<summary>\n";
				$str .= "\t\t{$shopProduct->getSummaryLine()}\n";
				$str .= "\t\t</summary>\n";
				$str .= "\t</product>\n";
			}
			$str .= '</products>\n';
			print $str;
	}
	
	class TextProductWriter extends ShopProductWriter {
		public function write () {
			$str = "ТОВАРЫ:\n";
			foreach ( $this->products as $shopProduct ) {
				$str .= $shopProduct->getSummaryLine()."\n";
			}
			print $str;
		}
	}

Интерфейсы

	interface Chargeable {
		public function getPrice();
	}

class ShopProduct implements Chargeable {
		private $title;
		private $producerMainName;
		private $producerFirstName;
		protected $price;
		private $discount = 0;
		private $id = 0;
		
		public function __construct ( $title, $firstName, $mainName, $price )
		{
			$this->title = $title;
			$this->producerMainName = $mainName;
			$this->producerFirstName = $firstName;
			$this->price = $price;
		}
		
		public function getProducerFirstName () {
			return $this->producerFirstName;
		}
		
		public function getProducerMainName () {
			return $this->producerMainName;
		}
		
		public function setDiscount ( $num ) {
			$this->discount = $num;
		}
		
		public function getDiscount() {
			return $this->discount;
		}
		
		public function getTitle() {
			return $this->title;
		}
		
		public function getPrice() {
			return ($this->price - $this->discount);
		}
		
		public function getProducer() {
			return "{$this->producerFirstName} "."{$this->producerMainName}";
		}
		
		public function getSummaryLine() {
			$base = "$this->title ( {$this->producerMainName}, ";
			$base .= "{$this->producerFirstName})";
			return $base;
		}
		
		public function setID ( $id ){
			$this->id = $id;
		}
		
		public static function getInstance ( $id, PDO $pdo ) {
			$stmt = $pdo->prepare("select * from products where id=?");
			$result = $stmt->execute ( array($id) );
			
			$row = $stmt->fetch();
			
			if (empty ($row) ) { return null; }
			
			if ( $row['type'] == 'book' ) {
				$product = new BookProduct($row['title'], 
										   $row['firstname'], 
										   $row['mainname'], 
										   $row['price'], 
										   $row['numpages']
										   );
				}
				else if ( $row['type'] == 'cd' ) {
				$product = new CDProduct ($row['title'], 
										  $row['firstname'], 
										  $row['mainname'], 
										  $row['price'], 
										  $row['playlength']
										  );
				}
				else 
				{
					$product = new ShopProduct ($row['title'], 
												$row['firstname'], 
												$row['mainname'], 
												$row['price']
												);
				}
				
				$product->setID( $row['id'] );
				$product->setDiscount ( $row['discount'] );
				return $product;
			}
		}

Позднее статическое связывание

	abstract class DomainObject {
		public static function create () {
			return new static();
		}
	}
	
	class User extends DomainObject {}
	
	class Document extends DomainObject {}
	
	print_r (Document::create());

<?php
	abstract class DomainObject 
	{
		private $group;
		
		public function __construct() {
			$this->group = static::getGroup();
		}
		
		public static function create ()
		{
			return new static();
		}
		
		static function getGroup() {
			return "default";
		}
	}
	
	class User extends DomainObject {}
	
	class Document extends DomainObject {
		static function getGroup() {
			return "document";
		}
	}
	
	class SpreadSheet extends Document {}
	
	print_r (User::create());
	print_r (SpreadSheet::create());
	
?>