理解PHP的工厂模式Factory Pattern

    
<?php
	class Fruit {
		// 对象从工厂类返回
	}
	
	Class FruitFactory {
		
		public static function factory() {
			// 返回对象的一个新实例
			return new Fruit();
		}
	}
	
	// 调用工厂
	$instance = FruitFactory::factory();
?>

    
<?php
class Example
{
    // The parameterized factory method
    public static function factory($type)
    {
        if (include_once 'Drivers/' . $type . '.php') {
            $classname = 'Driver_' . $type;
            return new $classname;
        } else {
            throw new Exception('Driver not found');
        }
    }
}
// Load a MySQL Driver
$mysql = Example::factory('MySQL');
// Load an SQLite Driver
$sqlite = Example::factory('SQLite');
?>

<?php
    
    /**
     * Generic Factory class
     *
     * This Magic Factory will remember all operations you perform on it,
     * and apply them to the object it instantiates.
     *
     */
    class FruitFactory {
        private $history, $class, $constructor_args;
        
        /**
         * Create a factory of given class. Accepts extra arguments to be passed to
         * class constructor.
         */
        function __construct( $class ) {
            $args = func_get_args();
            $this->class = $class;
            $this->constructor_args = array_slice( $args, 1 );
        }
        
        function __call( $method, $args ) {
            $this->history[] = array(
                'action'    => 'call',
                'method'    => $method,
                'args'   	=> $args
            );
        }
        
        function __set( $property, $value ) {
            $this->history[] = array(
                'action'    => 'set',
                'property'    => $property,
                'value'        => $value
            );
        }
        
        /**
         * Creates an instance and performs all operations that were done on this MagicFactory
         */
        function instance() {
            # use Reflection to create a new instance, using the $args 
            $reflection_object = new ReflectionClass( $this->class ); 
            $object = $reflection_object->newInstanceArgs( $this->constructor_args ); 
            
            # Alternative method that doesn't use ReflectionClass, but doesn't support variable
            # number of constructor parameters.
            //$object = new $this->class();
            
            # Repeat all remembered operations, apply to new object.
            foreach( $this->history as $item ) {
                if( $item['action'] == 'call' ) {
                    call_user_func_array( array( $object, $item['method'] ), $item['args'] );
                }
                if( $item['action'] == 'set' ) {
                    $object->{$item['property']} = $item['value'];
                }
            }
            
            # Done
            return $object;
        }
    }
    
    class Fruit {
        private $name, $color;
        public $price;
        
        function __construct( $name, $color ) {
            $this->name = $name;
            $this->color = $color;
        }
        
        function setName( $name ) {
            $this->name = $name;
        }
        
        function introduce() {
            print "Hello, this is an {$this->name} {$this->sirname}, its price is {$this->price} RMB.";
        }
    }
    
    # Setup a factory
    $fruit_factory = new FruitFactory('Fruit', 'Apple', 'Gonn');
    $fruit_factory->setName('Apple');
    $fruit_factory->price = 2;
    
    # Get an instance
    $apple = $fruit_factory->instance();
    $apple->introduce();
?>

Hello, this is an Apple , its price is 2 RMB.