组合模式

<?php
/**
 *  单元抽象类
 *  author caoxin 2014.7.18
 */
abstract class Unit
{
    /**
     * 作战能力
     */
    abstract public  function bomboardStrength();
      
}



/**
 *  弓箭手 
 *  author caoxin 2014.7.18
 */
class Archer extends Unit 
{
    /**
     * 作战能力
     */
    public  function bomboardStrength(){
        return 4;
        
    }
      
}

/**
 *  大炮 
 *  author caoxin 2014.7.18
 */
class  LaserCanonUnit extends Unit 
{
    /**
     * 作战能力
     */
    public  function bomboardStrength(){
        return 40;
        
    }
      
}


/**
 * 军队
 * author caoxin 2014.7.18
 */

class Army
{
    /**
     * 存储作战单元的数组
     * @var array
     */
    private $_units = array();

    /**
     * 添加作战单元
     */
    public function addUnit(Unit $unit){
        array_push($this->_units,$unit);
        
    }

   /**
    * 综合的作战能力
    */
    public function bomboardStrength(){
        $strength = 0;
        if(!empty($this->_units)){
            foreach( $this -> _units as $unit){
                $strength += $unit ->bomboardStrength();
            }
        }
        return $strength ;
    }


    
}


$army = new Army();
$army -> addUnit(new Archer() );
$army -> addUnit( new LaserCanonUnit());
$strengths = $army ->bomboardStrength();
echo $strengths;

?>