<?

//First Example: Address Validation
class Address { 
  function __construct(string $emailAddress) {
     //String validation on Address class violates SRP
     $this->validateEmail($emailAdress);
     //...
   }

  private function validateEmail(string $emailAddress) {
    $regex = "/[a-zA-Z0-9_-.+]+@[a-zA-Z0-9-]+.[a-zA-Z]+/";
    //Regex is a sample / It might be wrong
    //Emails and Urls should be first class objects

    if (!preg_match($regex, $emailAddress))
    {
      throw new Exception('Invalid email address ' . emailAddress);
    }    
  }
}

//Second Example: Wordle

class Wordle { 
  function validateWord(string $wordleword){
    //Wordle word should be a real world entity. Not a subset of strings
  }
 }

<?

//First Example: Address Validation
class Address { 
  function __construct(EmailAddress $emailAddress) {
     //Email is always valid / Code is cleaner     
     //...
   }
}

class EmailAddress { 
  //We can reuse this object many times avoiding copypasting
  string $address; 
  private function __construct(string $emailAddress) {
    $regex = "/[a-zA-Z0-9_-.+]+@[a-zA-Z0-9-]+.[a-zA-Z]+/";
    //Regex is a sample / It might be wrong
    //Emails and Urls are first class objects

    if (!preg_match($regex, $emailAddress))
    {
      throw new Exception('Invalid email address ' . emailAddress);
    }   
    $this->address = $emailAddress;
  }
}

//Second Example: Wordle

class Wordle { 
  function validateWord(WordleWord $wordleword){
    //Wordle word is a real world entity. Not a subset of string
  }
 }

class WordleWord { 
  function __construct(string $emailAddress)
    //Avoid building invalid world words
    //For example length != 5
  }
 }