Singleton & Factory, Dependency Injection, Data Mapper, Caching and Logging.

1. Zend Framework 3. Singleton & Factory, Dependency Injection, Data Mapper, Caching, Logging Tricode Professional Services www.tricode.nl Date: 27-02-2009 Authors: Marcel Blok Patrick van Dissel

3. Singleton class Logger { /** * @var Logger */ private static $instance = null; private function __construct () {} private function __clone() {} /** * @return Logger */ public static function getInstance() { if (! self :: $instance instanceof self ) { self :: $instance = new self (); } return self :: $instance ; } } <?php $a = Logger::getInstance(); $a ->methodX(..); $b = Logger::getInstance(); $a ->methodX(..); $a === $b

6. Dependency Injection How can Dependency Injection be applied to the following code? <?php class Book { public function __construct() { $this ->_databaseConnection = new DatabaseConnection(); // or global $databaseConnection ; $this ->_databaseConnection = $databaseConnection ; } }

8. Dependency Injection How is this? <?php class Book { public function __construct() { } public function setDatabaseConnection( $databaseConnection ) { $this ->_databaseConnection = $databaseConnection ; } } $book = new Book(); $book ->setDatabase( $databaseConnection );

9. Dependency Injection How is this? <?php class Book { public function __construct( $databaseConnection ) { … } protected function setDatabaseConnection( $databaseConnection ) { $this ->_databaseConnection = $databaseConnection ; } } $book = new Book( $databaseConnection );

10. Dependency Injection How is this? <?php class Factory { private static $_database; public static function makeBook() { $book = new Book(); $book ->setDatabase( self ::$_database ); // more injection... return $book ; } public static function setup( $database ) { …. } } $book = Factory::makeBook();

15. Factory <?php class Factory { private static $_database; public static function makeBook() { $book = new Book(); $book ->setDatabase( self ::$_database ); // more injection... return $book ; } public static function setup( $database ) { …. } } $book = Factory::makeBook();

19. Object-relational impedance mismatch  Database model Object model 

21. Data mapper Pattern

23. Database connection Like a singleton

24. Database connection With a factory

27. Zend_Cache Algorithm: No $data = false ; $data = $cache ->get(‘myKey’); if ( false === $data ) { $data = $db ->fetchOne(...); $cache ->save( $data , ‘myKey’); } echo $data ;

32. Zend_Log $logger = new Zend_Log(); $logger ->log(‘log this message’, Zend_Log::INFO); $logger ->info(‘log this message’);

33. Zend_Log Log priorities Debug messages 7 Zend_Log::DEBUG Informational messages 6 Zend_Log::INFO Notice: normal but significant conditions 5 Zend_Log::NOTICE Warning: warning conditions 4 Zend_Log::WARN Error: error conditions 3 Zend_Log::ERR Critical: critical conditions 2 Zend_Log::CRIT Alert: action must be taken immediately 1 Zend_Log::ALERT Emergency: system is unusable 0 Zend_Log::EMERGE Usage Value Name

34. Zend_Log Log writers Discards all log messages. This can be useful for turning off logging during testing or for disabling logging Zend_Log_writer_Null Sends log messages to the console in the Firebug extension of Firefox Zend_Log_writer_Firebug Stores logs to database records. You need to map the level and messages to two fields within a table Zend_Log_writer_Db Stores logs to files or other streams. The ‘php://output’ stream can be used to display to the output buffer Zend_Log_writer_Stream When to use Name

35. Zend_Log $logger = new Zend_Log(); // Log Warnings, Notices and Informational messages $writerMessages = new Zend_Log_Writer_Stream ($logsPath . 'messages.log'); $messageFilter1 = new Zend_Log_Filter_Priority(Zend_Log::WARN, '>='); $messageFilter2 = new Zend_Log_Filter_Priority(Zend_Log::INFO, '<='); $writerMessages ->addFilter( $messageFilter1 ); $writerMessages ->addFilter( $messageFilter2 ); $logger ->addWriter( $writerMessages );