PHP simple factory pattern example PHP design pattern introductory tutorial

/**
 * An example
 *
 * A farm wants to sell fruits to the market
 * There are three kinds of fruits on the farm, apples and grapes
 * We imagine: 1. Fruits have many attributes, and each attribute is different, but they have Common place | Growing, planting, receiving, eating
 * 2. New fruits may be added in the future. We need to define an interface to standardize the methods they must implement
 * 3. We need to obtain the class of a certain fruit, You need to get examples of a certain fruit from the farmer to know how to grow, plant, harvest and eat
*/
/**
 * Virtual product interface class
 * Define the methods that need to be implemented
*/
interface fruit{
  /**
 *Growth
*/
  public function grow();
  /**
 *Planting
*/
  public function plant();
  /**
 * Harvest
*/
  public function harvest();
  /**
 * Eat
*/
  public function eat();

}
/**
 * Define the specific product category Apple
 * First, we need to implement the methods defined by the inherited interface
 * Then define Apple-specific attributes and methods
*/
class apple implements fruit{
  //苹果树有年龄
  private $treeAge;
  //苹果有颜色
  private $color;
  public function grow(){
    echo "grape grow";
  }
  public function plant(){
    echo "grape plant";
  }
  public function harvest(){
    echo "grape harvest";
  }
  public function eat(){
    echo "grape eat";
  }
  //取苹果树的年龄
  public function getTreeAge(){
    return $this->treeAge;
  }
  //设置苹果树的年龄
  public function setTreeAge($age){
    $this->treeAge = $age;
    return trie;
  }
}
/**
 * Define the specific product class Grape
 * First, we need to implement the methods defined by the inherited interface
 * Then define the unique attributes and methods of Grape
*/
class grape implements fruit{
  //葡萄是否有籽
  private $seedLess;
  public function grow(){
    echo "apple grow";
  }
  public function plant(){
    echo "apple plant";
  }
  public function harvest(){
    echo "apple harvest";
  }
  public function eat(){
    echo "apple eat";
  }
  //有无籽取值
  public function getSeedLess(){
    return $this->seedLess;
  }
  //设置有籽无籽
  public function setSeedLess($seed){
    $this->seedLess = $seed;
    return true;
  }
}
/**
 *Farmer class is used to obtain instantiated fruits
 *
*/
class farmer{
  //定义个静态工厂方法
  public static function factory($fruitName){
    switch ($fruitName) {
      case 'apple':
        return new apple();
        break;
      case 'grape':
        return new grape();
        break;
      default:
        throw new badFruitException("Error no the fruit", 1);
        break;
    }
  }
}
class badFruitException extends Exception{
  public $msg;
  public $errType;
  public function __construct($msg = '' , $errType = 1){
    $this->msg = $msg;
    $this->errType = $errType;
  }
}
/**
 * Method to obtain fruit instantiation
*/
try{
  $appleInstance = farmer::factory('apple');
  var_dump($appleInstance);
}catch(badFruitException $err){
  echo $err->msg . "_______" . $err->errType;
}