As I promised before, here are all the classes that I built over the course of this tutorial to apply the strategy pattern with PHP 5:

// define 'ValidationStrategySelector' class
class ValidationStrategySelector{
   private $strategy=NULL;
   public function __construct($strategy){
     if($strategy!='alpha'&&$strategy!='alphanum'&&$strategy!
='number'&&$strategy!='email'){
       throw new Exception('Invalid parameter for validation
strategy!');
     }
     switch($strategy){
       case "alpha": 
         $this->strategy=new StrategyAlphabetic();
         break;
       case "alphanum": 
         $this->strategy=new StrategyAlphanumeric();
         break;
       case "number": 
         $this->strategy=new StrategyNumber();
         break;
       case "email": 
         $this->strategy=new StrategyEmail();
         break;
     }
   }
   public function validateData($inputData){
     if(!$this->strategy->validateData($inputData)){
       return 'Input data is not valid!';
     }
     return 'Input data is OK!';
   }
}
// define 'StrategyAlphabetic' class
class StrategyAlphabetic{
   public function validateData($inputData){
     if(!$inputData||!preg_match("/^[a-zA-Z]+$/",$inputData)){
       return false;
     }
     return true;
   }
}
// define 'StrategyAlphanumeric' class
class StrategyAlphanumeric{
   public function validateData($inputData){
     if(!$inputData||!preg_match("/^[a-zA-Z0-9]+$/",$inputData)){
       return false;
     }
     return true;
   }
}
// define 'StrategyNumber' class
class StrategyNumber{
   public function validateData($inputData){
     if(!$inputData||!is_numeric($inputData)){
       return false;
     }
     return true;
   }
}
// define 'StrategyEmail' class
class StrategyEmail{
   public function validateData($inputData){
     if(!$inputData||!preg_match("/.+@.+..+./",$inputData)||!
checkdnsrr(array_pop(explode("@",$inputData)),"MX")){
       return false;
     }
     return true;
   }          
}

That's it. As usual with all my articles, feel free to modify the signature of all the classes that I showed here so you can acquire a better understanding of this pattern. Have a good time!

Final thoughts

Unfortunately, we've come to the end of this series. However, I hope that after reading these two articles, you'll have a better idea not only of how the strategy pattern works, but how it can be used in real situations.

See you in the next PHP tutorial!